From 5a4f391433cbc7b94edb1f30ae3a835e5e320d0f Mon Sep 17 00:00:00 2001 From: Brian Pane Date: Sat, 27 Nov 2004 19:43:25 +0000 Subject: Removed the documentation files because they were making the httpd source checkout too large, added a README file pointing to the reference copy of the docs in the PCRE vendor branch git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@106747 13f79535-47bb-0310-9956-ffa450edef68 --- srclib/pcre/doc/README_httpd | 6 + srclib/pcre/doc/Tech.Notes | 315 -- srclib/pcre/doc/html/index.html | 108 - srclib/pcre/doc/html/pcre.html | 214 -- srclib/pcre/doc/html/pcre_compile.html | 75 - srclib/pcre/doc/html/pcre_config.html | 60 - .../pcre/doc/html/pcre_copy_named_substring.html | 53 - srclib/pcre/doc/html/pcre_copy_substring.html | 51 - srclib/pcre/doc/html/pcre_exec.html | 78 - srclib/pcre/doc/html/pcre_free_substring.html | 40 - srclib/pcre/doc/html/pcre_free_substring_list.html | 40 - srclib/pcre/doc/html/pcre_fullinfo.html | 71 - srclib/pcre/doc/html/pcre_get_named_substring.html | 54 - 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srclib/pcre/doc/pcreposix.3 | 201 -- srclib/pcre/doc/pcreposix.html | 191 - srclib/pcre/doc/pcreposix.txt | 159 - srclib/pcre/doc/pcreprecompile.3 | 125 - srclib/pcre/doc/pcresample.3 | 66 - srclib/pcre/doc/pcretest.1 | 483 --- srclib/pcre/doc/pcretest.html | 369 -- srclib/pcre/doc/pcretest.txt | 450 --- srclib/pcre/doc/perltest.txt | 33 - srclib/pcre/doc/pgrep.1 | 76 - srclib/pcre/doc/pgrep.html | 105 - srclib/pcre/doc/pgrep.txt | 86 - 73 files changed, 6 insertions(+), 19441 deletions(-) create mode 100644 srclib/pcre/doc/README_httpd delete mode 100644 srclib/pcre/doc/Tech.Notes delete mode 100644 srclib/pcre/doc/html/index.html delete mode 100644 srclib/pcre/doc/html/pcre.html delete mode 100644 srclib/pcre/doc/html/pcre_compile.html delete mode 100644 srclib/pcre/doc/html/pcre_config.html delete mode 100644 srclib/pcre/doc/html/pcre_copy_named_substring.html delete mode 100644 srclib/pcre/doc/html/pcre_copy_substring.html delete mode 100644 srclib/pcre/doc/html/pcre_exec.html delete mode 100644 srclib/pcre/doc/html/pcre_free_substring.html delete mode 100644 srclib/pcre/doc/html/pcre_free_substring_list.html delete mode 100644 srclib/pcre/doc/html/pcre_fullinfo.html delete mode 100644 srclib/pcre/doc/html/pcre_get_named_substring.html delete mode 100644 srclib/pcre/doc/html/pcre_get_stringnumber.html delete mode 100644 srclib/pcre/doc/html/pcre_get_substring.html delete mode 100644 srclib/pcre/doc/html/pcre_get_substring_list.html delete mode 100644 srclib/pcre/doc/html/pcre_info.html delete mode 100644 srclib/pcre/doc/html/pcre_maketables.html delete mode 100644 srclib/pcre/doc/html/pcre_study.html delete mode 100644 srclib/pcre/doc/html/pcre_version.html delete mode 100644 srclib/pcre/doc/html/pcreapi.html delete mode 100644 srclib/pcre/doc/html/pcrebuild.html delete mode 100644 srclib/pcre/doc/html/pcrecallout.html delete mode 100644 srclib/pcre/doc/html/pcrecompat.html delete mode 100644 srclib/pcre/doc/html/pcregrep.html delete mode 100644 srclib/pcre/doc/html/pcrepartial.html delete mode 100644 srclib/pcre/doc/html/pcrepattern.html delete mode 100644 srclib/pcre/doc/html/pcreperform.html delete mode 100644 srclib/pcre/doc/html/pcreposix.html delete mode 100644 srclib/pcre/doc/html/pcreprecompile.html delete mode 100644 srclib/pcre/doc/html/pcresample.html delete mode 100644 srclib/pcre/doc/html/pcretest.html delete mode 100644 srclib/pcre/doc/pcre.3 delete mode 100644 srclib/pcre/doc/pcre.html delete mode 100644 srclib/pcre/doc/pcre.txt delete mode 100644 srclib/pcre/doc/pcre_compile.3 delete mode 100644 srclib/pcre/doc/pcre_config.3 delete mode 100644 srclib/pcre/doc/pcre_copy_named_substring.3 delete mode 100644 srclib/pcre/doc/pcre_copy_substring.3 delete mode 100644 srclib/pcre/doc/pcre_exec.3 delete mode 100644 srclib/pcre/doc/pcre_free_substring.3 delete mode 100644 srclib/pcre/doc/pcre_free_substring_list.3 delete mode 100644 srclib/pcre/doc/pcre_fullinfo.3 delete mode 100644 srclib/pcre/doc/pcre_get_named_substring.3 delete mode 100644 srclib/pcre/doc/pcre_get_stringnumber.3 delete mode 100644 srclib/pcre/doc/pcre_get_substring.3 delete mode 100644 srclib/pcre/doc/pcre_get_substring_list.3 delete mode 100644 srclib/pcre/doc/pcre_info.3 delete mode 100644 srclib/pcre/doc/pcre_maketables.3 delete mode 100644 srclib/pcre/doc/pcre_study.3 delete mode 100644 srclib/pcre/doc/pcre_version.3 delete mode 100644 srclib/pcre/doc/pcreapi.3 delete mode 100644 srclib/pcre/doc/pcrebuild.3 delete mode 100644 srclib/pcre/doc/pcrecallout.3 delete mode 100644 srclib/pcre/doc/pcrecompat.3 delete mode 100644 srclib/pcre/doc/pcregrep.1 delete mode 100644 srclib/pcre/doc/pcregrep.html delete mode 100644 srclib/pcre/doc/pcregrep.txt delete mode 100644 srclib/pcre/doc/pcrepartial.3 delete mode 100644 srclib/pcre/doc/pcrepattern.3 delete mode 100644 srclib/pcre/doc/pcreperform.3 delete mode 100644 srclib/pcre/doc/pcreposix.3 delete mode 100644 srclib/pcre/doc/pcreposix.html delete mode 100644 srclib/pcre/doc/pcreposix.txt delete mode 100644 srclib/pcre/doc/pcreprecompile.3 delete mode 100644 srclib/pcre/doc/pcresample.3 delete mode 100644 srclib/pcre/doc/pcretest.1 delete mode 100644 srclib/pcre/doc/pcretest.html delete mode 100644 srclib/pcre/doc/pcretest.txt delete mode 100644 srclib/pcre/doc/perltest.txt delete mode 100644 srclib/pcre/doc/pgrep.1 delete mode 100644 srclib/pcre/doc/pgrep.html delete mode 100644 srclib/pcre/doc/pgrep.txt (limited to 'srclib') diff --git a/srclib/pcre/doc/README_httpd b/srclib/pcre/doc/README_httpd new file mode 100644 index 0000000000..322c39c4f2 --- /dev/null +++ b/srclib/pcre/doc/README_httpd @@ -0,0 +1,6 @@ +The documentation directory has been omitted from this copy of PCRE +inside the httpd codebase because it's huge--over a megabyte of PCRE docs. + +The PCRE documentation directory is available in unmodified form in the +vendor branch. You can access it via web browser or Subversion checkout at +http://svn.apache.org/repos/asf/httpd/httpd/vendor/pcre/current/doc/ diff --git a/srclib/pcre/doc/Tech.Notes b/srclib/pcre/doc/Tech.Notes deleted file mode 100644 index 18eb72bce7..0000000000 --- a/srclib/pcre/doc/Tech.Notes +++ /dev/null @@ -1,315 +0,0 @@ -Technical Notes about PCRE --------------------------- - -Historical note 1 ------------------ - -Many years ago I implemented some regular expression functions to an algorithm -suggested by Martin Richards. These were not Unix-like in form, and were quite -restricted in what they could do by comparison with Perl. The interesting part -about the algorithm was that the amount of space required to hold the compiled -form of an expression was known in advance. The code to apply an expression did -not operate by backtracking, as the original Henry Spencer code and current -Perl code does, but instead checked all possibilities simultaneously by keeping -a list of current states and checking all of them as it advanced through the -subject string. In the terminology of Jeffrey Friedl's book, it was a "DFA -algorithm". When the pattern was all used up, all remaining states were -possible matches, and the one matching the longest subset of the subject string -was chosen. This did not necessarily maximize the individual wild portions of -the pattern, as is expected in Unix and Perl-style regular expressions. - -Historical note 2 ------------------ - -By contrast, the code originally written by Henry Spencer and subsequently -heavily modified for Perl actually compiles the expression twice: once in a -dummy mode in order to find out how much store will be needed, and then for -real. The execution function operates by backtracking and maximizing (or, -optionally, minimizing in Perl) the amount of the subject that matches -individual wild portions of the pattern. This is an "NFA algorithm" in Friedl's -terminology. - -OK, here's the real stuff -------------------------- - -For the set of functions that forms PCRE (which are unrelated to those -mentioned above), I tried at first to invent an algorithm that used an amount -of store bounded by a multiple of the number of characters in the pattern, to -save on compiling time. However, because of the greater complexity in Perl -regular expressions, I couldn't do this. In any case, a first pass through the -pattern is needed, for a number of reasons. PCRE works by running a very -degenerate first pass to calculate a maximum store size, and then a second pass -to do the real compile - which may use a bit less than the predicted amount of -store. The idea is that this is going to turn out faster because the first pass -is degenerate and the second pass can just store stuff straight into the -vector. It does make the compiling functions bigger, of course, but they have -got quite big anyway to handle all the Perl stuff. - -The compiled form of a pattern is a vector of bytes, containing items of -variable length. The first byte in an item is an opcode, and the length of the -item is either implicit in the opcode or contained in the data bytes that -follow it. - -In many cases below "two-byte" data values are specified. This is in fact just -a default. PCRE can be compiled to use 3-byte or 4-byte values (impairing the -performance). This is necessary only when patterns whose compiled length is -greater than 64K are going to be processed. In this description, we assume the -"normal" compilation options. - -A list of all the opcodes follows: - -Opcodes with no following data ------------------------------- - -These items are all just one byte long - - OP_END end of pattern - OP_ANY match any character - OP_ANYBYTE match any single byte, even in UTF-8 mode - OP_SOD match start of data: \A - OP_SOM, start of match (subject + offset): \G - OP_CIRC ^ (start of data, or after \n in multiline) - OP_NOT_WORD_BOUNDARY \W - OP_WORD_BOUNDARY \w - OP_NOT_DIGIT \D - OP_DIGIT \d - OP_NOT_WHITESPACE \S - OP_WHITESPACE \s - OP_NOT_WORDCHAR \W - OP_WORDCHAR \w - OP_EODN match end of data or \n at end: \Z - OP_EOD match end of data: \z - OP_DOLL $ (end of data, or before \n in multiline) - OP_EXTUNI match an extended Unicode character - - -Repeating single characters ---------------------------- - -The common repeats (*, +, ?) when applied to a single character use the -following opcodes: - - OP_STAR - OP_MINSTAR - OP_PLUS - OP_MINPLUS - OP_QUERY - OP_MINQUERY - -In ASCII mode, these are two-byte items; in UTF-8 mode, the length is variable. -Those with "MIN" in their name are the minimizing versions. Each is followed by -the character that is to be repeated. Other repeats make use of - - OP_UPTO - OP_MINUPTO - OP_EXACT - -which are followed by a two-byte count (most significant first) and the -repeated character. OP_UPTO matches from 0 to the given number. A repeat with a -non-zero minimum and a fixed maximum is coded as an OP_EXACT followed by an -OP_UPTO (or OP_MINUPTO). - - -Repeating character types -------------------------- - -Repeats of things like \d are done exactly as for single characters, except -that instead of a character, the opcode for the type is stored in the data -byte. The opcodes are: - - OP_TYPESTAR - OP_TYPEMINSTAR - OP_TYPEPLUS - OP_TYPEMINPLUS - OP_TYPEQUERY - OP_TYPEMINQUERY - OP_TYPEUPTO - OP_TYPEMINUPTO - OP_TYPEEXACT - - -Match by Unicode property -------------------------- - -OP_PROP and OP_NOTPROP are used for positive and negative matches of a -character by testing its Unicode property (the \p and \P escape sequences). -Each is followed by a single byte that encodes the desired property value. - -Repeats of these items use the OP_TYPESTAR etc. set of opcodes, followed by two -bytes: OP_PROP or OP_NOTPROP and then the desired property value. - - -Matching literal characters ---------------------------- - -The OP_CHAR opcode is followed by a single character that is to be matched -casefully. For caseless matching, OP_CHARNC is used. In UTF-8 mode, the -character may be more than one byte long. (Earlier versions of PCRE used -multi-character strings, but this was changed to allow some new features to be -added.) - - -Character classes ------------------ - -If there is only one character, OP_CHAR or OP_CHARNC is used for a positive -class, and OP_NOT for a negative one (that is, for something like [^a]). -However, in UTF-8 mode, the use of OP_NOT applies only to characters with -values < 128, because OP_NOT is confined to single bytes. - -Another set of repeating opcodes (OP_NOTSTAR etc.) are used for a repeated, -negated, single-character class. The normal ones (OP_STAR etc.) are used for a -repeated positive single-character class. - -When there's more than one character in a class and all the characters are less -than 256, OP_CLASS is used for a positive class, and OP_NCLASS for a negative -one. In either case, the opcode is followed by a 32-byte bit map containing a 1 -bit for every character that is acceptable. The bits are counted from the least -significant end of each byte. - -The reason for having both OP_CLASS and OP_NCLASS is so that, in UTF-8 mode, -subject characters with values greater than 256 can be handled correctly. For -OP_CLASS they don't match, whereas for OP_NCLASS they do. - -For classes containing characters with values > 255, OP_XCLASS is used. It -optionally uses a bit map (if any characters lie within it), followed by a list -of pairs and single characters. There is a flag character than indicates -whether it's a positive or a negative class. - - -Back references ---------------- - -OP_REF is followed by two bytes containing the reference number. - - -Repeating character classes and back references ------------------------------------------------ - -Single-character classes are handled specially (see above). This applies to -OP_CLASS and OP_REF. In both cases, the repeat information follows the base -item. The matching code looks at the following opcode to see if it is one of - - OP_CRSTAR - OP_CRMINSTAR - OP_CRPLUS - OP_CRMINPLUS - OP_CRQUERY - OP_CRMINQUERY - OP_CRRANGE - OP_CRMINRANGE - -All but the last two are just single-byte items. The others are followed by -four bytes of data, comprising the minimum and maximum repeat counts. - - -Brackets and alternation ------------------------- - -A pair of non-capturing (round) brackets is wrapped round each expression at -compile time, so alternation always happens in the context of brackets. - -Non-capturing brackets use the opcode OP_BRA, while capturing brackets use -OP_BRA+1, OP_BRA+2, etc. [Note for North Americans: "bracket" to some English -speakers, including myself, can be round, square, curly, or pointy. Hence this -usage.] - -Originally PCRE was limited to 99 capturing brackets (so as not to use up all -the opcodes). From release 3.5, there is no limit. What happens is that the -first ones, up to EXTRACT_BASIC_MAX are handled with separate opcodes, as -above. If there are more, the opcode is set to EXTRACT_BASIC_MAX+1, and the -first operation in the bracket is OP_BRANUMBER, followed by a 2-byte bracket -number. This opcode is ignored while matching, but is fished out when handling -the bracket itself. (They could have all been done like this, but I was making -minimal changes.) - -A bracket opcode is followed by two bytes which give the offset to the next -alternative OP_ALT or, if there aren't any branches, to the matching OP_KET -opcode. Each OP_ALT is followed by two bytes giving the offset to the next one, -or to the OP_KET opcode. - -OP_KET is used for subpatterns that do not repeat indefinitely, while -OP_KETRMIN and OP_KETRMAX are used for indefinite repetitions, minimally or -maximally respectively. All three are followed by two bytes giving (as a -positive number) the offset back to the matching OP_BRA opcode. - -If a subpattern is quantified such that it is permitted to match zero times, it -is preceded by one of OP_BRAZERO or OP_BRAMINZERO. These are single-byte -opcodes which tell the matcher that skipping this subpattern entirely is a -valid branch. - -A subpattern with an indefinite maximum repetition is replicated in the -compiled data its minimum number of times (or once with OP_BRAZERO if the -minimum is zero), with the final copy terminating with OP_KETRMIN or OP_KETRMAX -as appropriate. - -A subpattern with a bounded maximum repetition is replicated in a nested -fashion up to the maximum number of times, with OP_BRAZERO or OP_BRAMINZERO -before each replication after the minimum, so that, for example, (abc){2,5} is -compiled as (abc)(abc)((abc)((abc)(abc)?)?)?. - - -Assertions ----------- - -Forward assertions are just like other subpatterns, but starting with one of -the opcodes OP_ASSERT or OP_ASSERT_NOT. Backward assertions use the opcodes -OP_ASSERTBACK and OP_ASSERTBACK_NOT, and the first opcode inside the assertion -is OP_REVERSE, followed by a two byte count of the number of characters to move -back the pointer in the subject string. When operating in UTF-8 mode, the count -is a character count rather than a byte count. A separate count is present in -each alternative of a lookbehind assertion, allowing them to have different -fixed lengths. - - -Once-only subpatterns ---------------------- - -These are also just like other subpatterns, but they start with the opcode -OP_ONCE. - - -Conditional subpatterns ------------------------ - -These are like other subpatterns, but they start with the opcode OP_COND. If -the condition is a back reference, this is stored at the start of the -subpattern using the opcode OP_CREF followed by two bytes containing the -reference number. If the condition is "in recursion" (coded as "(?(R)"), the -same scheme is used, with a "reference number" of 0xffff. Otherwise, a -conditional subpattern always starts with one of the assertions. - - -Recursion ---------- - -Recursion either matches the current regex, or some subexpression. The opcode -OP_RECURSE is followed by an value which is the offset to the starting bracket -from the start of the whole pattern. - - -Callout -------- - -OP_CALLOUT is followed by one byte of data that holds a callout number in the -range 0 to 254 for manual callouts, or 255 for an automatic callout. In both -cases there follows a two-byte value giving the offset in the pattern to the -start of the following item, and another two-byte item giving the length of the -next item. - - -Changing options ----------------- - -If any of the /i, /m, or /s options are changed within a pattern, an OP_OPT -opcode is compiled, followed by one byte containing the new settings of these -flags. If there are several alternatives, there is an occurrence of OP_OPT at -the start of all those following the first options change, to set appropriate -options for the start of the alternative. Immediately after the end of the -group there is another such item to reset the flags to their previous values. A -change of flag right at the very start of the pattern can be handled entirely -at compile time, and so does not cause anything to be put into the compiled -data. - -Philip Hazel -September 2004 diff --git a/srclib/pcre/doc/html/index.html b/srclib/pcre/doc/html/index.html deleted file mode 100644 index c0dbf59d15..0000000000 --- a/srclib/pcre/doc/html/index.html +++ /dev/null @@ -1,108 +0,0 @@ - - -PCRE specification - - -

Perl-compatible Regular Expressions (PCRE)

-

-The HTML documentation for PCRE comprises the following pages: -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
pcre  Introductory page
pcreapi  PCRE's native API
pcrebuild  Options for building PCRE
pcrecallout  The callout facility
pcrecompat  Compability with Perl
pcregrep  The pcregrep command
pcrepartial  Using PCRE for partial matching
pcrepattern  Specification of the regular expressions supported by PCRE
pcreperform  Some comments on performance
pcreposix  The POSIX API to the PCRE library
pcreprecompile  How to save and re-use compiled patterns
pcresample  Description of the sample program
pcretest  The pcretest command for testing PCRE
- -

-There are also individual pages that summarize the interface for each function -in the library: -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
pcre_compile  Compile a regular expression
pcre_config  Show build-time configuration options
pcre_copy_named_substring  Extract named substring into given buffer
pcre_copy_substring  Extract numbered substring into given buffer
pcre_exec  Match a compiled pattern to a subject string
pcre_free_substring  Free extracted substring
pcre_free_substring_list  Free list of extracted substrings
pcre_fullinfo  Extract information about a pattern
pcre_get_named_substring  Extract named substring into new memory
pcre_get_stringnumber  Convert captured string name to number
pcre_get_substring  Extract numbered substring into new memory
pcre_get_substring_list  Extract all substrings into new memory
pcre_info  Obsolete information extraction function
pcre_maketables  Build character tables in current locale
pcre_study  Study a compiled pattern
pcre_version  Return PCRE version and release date
- - diff --git a/srclib/pcre/doc/html/pcre.html b/srclib/pcre/doc/html/pcre.html deleted file mode 100644 index b1caf80701..0000000000 --- a/srclib/pcre/doc/html/pcre.html +++ /dev/null @@ -1,214 +0,0 @@ - - -pcre specification - - -

pcre man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
INTRODUCTION
-

-The PCRE library is a set of functions that implement regular expression -pattern matching using the same syntax and semantics as Perl, with just a few -differences. The current implementation of PCRE (release 5.x) corresponds -approximately with Perl 5.8, including support for UTF-8 encoded strings and -Unicode general category properties. However, this support has to be explicitly -enabled; it is not the default. -

-

-PCRE is written in C and released as a C library. A number of people have -written wrappers and interfaces of various kinds. A C++ class is included in -these contributions, which can be found in the Contrib directory at the -primary FTP site, which is: -ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre -

-

-Details of exactly which Perl regular expression features are and are not -supported by PCRE are given in separate documents. See the -pcrepattern -and -pcrecompat -pages. -

-

-Some features of PCRE can be included, excluded, or changed when the library is -built. The -pcre_config() -function makes it possible for a client to discover which features are -available. The features themselves are described in the -pcrebuild -page. Documentation about building PCRE for various operating systems can be -found in the README file in the source distribution. -

-
USER DOCUMENTATION
-

-The user documentation for PCRE comprises a number of different sections. In -the "man" format, each of these is a separate "man page". In the HTML format, -each is a separate page, linked from the index page. In the plain text format, -all the sections are concatenated, for ease of searching. The sections are as -follows: -

-  pcre              this document
-  pcreapi           details of PCRE's native API
-  pcrebuild         options for building PCRE
-  pcrecallout       details of the callout feature
-  pcrecompat        discussion of Perl compatibility
-  pcregrep          description of the pcregrep command
-  pcrepartial       details of the partial matching facility
-  pcrepattern       syntax and semantics of supported regular expressions
-  pcreperform       discussion of performance issues
-  pcreposix         the POSIX-compatible API
-  pcreprecompile    details of saving and re-using precompiled patterns
-  pcresample        discussion of the sample program
-  pcretest          description of the pcretest testing command
-
-In addition, in the "man" and HTML formats, there is a short page for each -library function, listing its arguments and results. -

-
LIMITATIONS
-

-There are some size limitations in PCRE but it is hoped that they will never in -practice be relevant. -

-

-The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is -compiled with the default internal linkage size of 2. If you want to process -regular expressions that are truly enormous, you can compile PCRE with an -internal linkage size of 3 or 4 (see the README file in the source -distribution and the -pcrebuild -documentation for details). In these cases the limit is substantially larger. -However, the speed of execution will be slower. -

-

-All values in repeating quantifiers must be less than 65536. -The maximum number of capturing subpatterns is 65535. -

-

-There is no limit to the number of non-capturing subpatterns, but the maximum -depth of nesting of all kinds of parenthesized subpattern, including capturing -subpatterns, assertions, and other types of subpattern, is 200. -

-

-The maximum length of a subject string is the largest positive number that an -integer variable can hold. However, PCRE uses recursion to handle subpatterns -and indefinite repetition. This means that the available stack space may limit -the size of a subject string that can be processed by certain patterns. -

-
UTF-8 AND UNICODE PROPERTY SUPPORT
-

-From release 3.3, PCRE has had some support for character strings encoded in -the UTF-8 format. For release 4.0 this was greatly extended to cover most -common requirements, and in release 5.0 additional support for Unicode general -category properties was added. -

-

-In order process UTF-8 strings, you must build PCRE to include UTF-8 support in -the code, and, in addition, you must call -pcre_compile() -with the PCRE_UTF8 option flag. When you do this, both the pattern and any -subject strings that are matched against it are treated as UTF-8 strings -instead of just strings of bytes. -

-

-If you compile PCRE with UTF-8 support, but do not use it at run time, the -library will be a bit bigger, but the additional run time overhead is limited -to testing the PCRE_UTF8 flag in several places, so should not be very large. -

-

-If PCRE is built with Unicode character property support (which implies UTF-8 -support), the escape sequences \p{..}, \P{..}, and \X are supported. -The available properties that can be tested are limited to the general -category properties such as Lu for an upper case letter or Nd for a decimal -number. A full list is given in the -pcrepattern -documentation. The PCRE library is increased in size by about 90K when Unicode -property support is included. -

-

-The following comments apply when PCRE is running in UTF-8 mode: -

-

-1. When you set the PCRE_UTF8 flag, the strings passed as patterns and subjects -are checked for validity on entry to the relevant functions. If an invalid -UTF-8 string is passed, an error return is given. In some situations, you may -already know that your strings are valid, and therefore want to skip these -checks in order to improve performance. If you set the PCRE_NO_UTF8_CHECK flag -at compile time or at run time, PCRE assumes that the pattern or subject it -is given (respectively) contains only valid UTF-8 codes. In this case, it does -not diagnose an invalid UTF-8 string. If you pass an invalid UTF-8 string to -PCRE when PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program -may crash. -

-

-2. In a pattern, the escape sequence \x{...}, where the contents of the braces -is a string of hexadecimal digits, is interpreted as a UTF-8 character whose -code number is the given hexadecimal number, for example: \x{1234}. If a -non-hexadecimal digit appears between the braces, the item is not recognized. -This escape sequence can be used either as a literal, or within a character -class. -

-

-3. The original hexadecimal escape sequence, \xhh, matches a two-byte UTF-8 -character if the value is greater than 127. -

-

-4. Repeat quantifiers apply to complete UTF-8 characters, not to individual -bytes, for example: \x{100}{3}. -

-

-5. The dot metacharacter matches one UTF-8 character instead of a single byte. -

-

-6. The escape sequence \C can be used to match a single byte in UTF-8 mode, -but its use can lead to some strange effects. -

-

-7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly -test characters of any code value, but the characters that PCRE recognizes as -digits, spaces, or word characters remain the same set as before, all with -values less than 256. This remains true even when PCRE includes Unicode -property support, because to do otherwise would slow down PCRE in many common -cases. If you really want to test for a wider sense of, say, "digit", you -must use Unicode property tests such as \p{Nd}. -

-

-8. Similarly, characters that match the POSIX named character classes are all -low-valued characters. -

-

-9. Case-insensitive matching applies only to characters whose values are less -than 128, unless PCRE is built with Unicode property support. Even when Unicode -property support is available, PCRE still uses its own character tables when -checking the case of low-valued characters, so as not to degrade performance. -The Unicode property information is used only for characters with higher -values. -

-
AUTHOR
-

-Philip Hazel <ph10@cam.ac.uk> -
-University Computing Service, -
-Cambridge CB2 3QG, England. -
-Phone: +44 1223 334714 -Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_compile.html b/srclib/pcre/doc/html/pcre_compile.html deleted file mode 100644 index 0d417a1fc9..0000000000 --- a/srclib/pcre/doc/html/pcre_compile.html +++ /dev/null @@ -1,75 +0,0 @@ - - -pcre_compile specification - - -

pcre_compile man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-pcre *pcre_compile(const char *pattern, int options, -const char **errptr, int *erroffset, -const unsigned char *tableptr); -

-
-DESCRIPTION -
-

-This function compiles a regular expression into an internal form. Its -arguments are: -

-  pattern       A zero-terminated string containing the
-                  regular expression to be compiled
-  options       Zero or more option bits
-  errptr        Where to put an error message
-  erroffset     Offset in pattern where error was found
-  tableptr      Pointer to character tables, or NULL to
-                  use the built-in default
-
-The option bits are: -
-  PCRE_ANCHORED         Force pattern anchoring
-  PCRE_AUTO_CALLOUT     Compile automatic callouts
-  PCRE_CASELESS         Do caseless matching
-  PCRE_DOLLAR_ENDONLY   $ not to match newline at end
-  PCRE_DOTALL           . matches anything including NL
-  PCRE_EXTENDED         Ignore whitespace and # comments
-  PCRE_EXTRA            PCRE extra features
-                          (not much use currently)
-  PCRE_MULTILINE        ^ and $ match newlines within data
-  PCRE_NO_AUTO_CAPTURE  Disable numbered capturing paren-
-                          theses (named ones available)
-  PCRE_UNGREEDY         Invert greediness of quantifiers
-  PCRE_UTF8             Run in UTF-8 mode
-  PCRE_NO_UTF8_CHECK    Do not check the pattern for UTF-8
-                          validity (only relevant if
-                          PCRE_UTF8 is set)
-
-PCRE must be built with UTF-8 support in order to use PCRE_UTF8 and -PCRE_NO_UTF8_CHECK. -

-

-The yield of the function is a pointer to a private data structure that -contains the compiled pattern, or NULL if an error was detected. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_config.html b/srclib/pcre/doc/html/pcre_config.html deleted file mode 100644 index 8d8cc6073d..0000000000 --- a/srclib/pcre/doc/html/pcre_config.html +++ /dev/null @@ -1,60 +0,0 @@ - - -pcre_config specification - - -

pcre_config man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_config(int what, void *where); -

-
-DESCRIPTION -
-

-This function makes it possible for a client program to find out which optional -features are available in the version of the PCRE library it is using. Its -arguments are as follows: -

-  what     A code specifying what information is required
-  where    Points to where to put the data
-
-The available codes are: -
-  PCRE_CONFIG_LINK_SIZE     Internal link size: 2, 3, or 4
-  PCRE_CONFIG_MATCH_LIMIT   Internal resource limit
-  PCRE_CONFIG_NEWLINE       Value of the newline character
-  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
-                            Threshold of return slots, above
-                              which malloc() is used by
-                              the POSIX API
-  PCRE_CONFIG_STACKRECURSE  Recursion implementation (1=stack 0=heap)
-  PCRE_CONFIG_UTF8          Availability of UTF-8 support (1=yes 0=no)
-  PCRE_CONFIG_UNICODE_PROPERTIES
-                            Availability of Unicode property support
-                              (1=yes 0=no)
-
-The function yields 0 on success or PCRE_ERROR_BADOPTION otherwise. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_copy_named_substring.html b/srclib/pcre/doc/html/pcre_copy_named_substring.html deleted file mode 100644 index 2185518c8a..0000000000 --- a/srclib/pcre/doc/html/pcre_copy_named_substring.html +++ /dev/null @@ -1,53 +0,0 @@ - - -pcre_copy_named_substring specification - - -

pcre_copy_named_substring man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_copy_named_substring(const pcre *code, -const char *subject, int *ovector, -int stringcount, const char *stringname, -char *buffer, int buffersize); -

-
-DESCRIPTION -
-

-This is a convenience function for extracting a captured substring, identified -by name, into a given buffer. The arguments are: -

-  code          Pattern that was successfully matched
-  subject       Subject that has been successfully matched
-  ovector       Offset vector that pcre_exec() used
-  stringcount   Value returned by pcre_exec()
-  stringname    Name of the required substring
-  buffer        Buffer to receive the string
-  buffersize    Size of buffer
-
-The yield is the length of the substring, PCRE_ERROR_NOMEMORY if the buffer was -too small, or PCRE_ERROR_NOSUBSTRING if the string name is invalid. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_copy_substring.html b/srclib/pcre/doc/html/pcre_copy_substring.html deleted file mode 100644 index 9aa87c1746..0000000000 --- a/srclib/pcre/doc/html/pcre_copy_substring.html +++ /dev/null @@ -1,51 +0,0 @@ - - -pcre_copy_substring specification - - -

pcre_copy_substring man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_copy_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, char *buffer, -int buffersize); -

-
-DESCRIPTION -
-

-This is a convenience function for extracting a captured substring into a given -buffer. The arguments are: -

-  subject       Subject that has been successfully matched
-  ovector       Offset vector that pcre_exec() used
-  stringcount   Value returned by pcre_exec()
-  stringnumber  Number of the required substring
-  buffer        Buffer to receive the string
-  buffersize    Size of buffer
-
-The yield is the legnth of the string, PCRE_ERROR_NOMEMORY if the buffer was -too small, or PCRE_ERROR_NOSUBSTRING if the string number is invalid. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_exec.html b/srclib/pcre/doc/html/pcre_exec.html deleted file mode 100644 index fc3d32282d..0000000000 --- a/srclib/pcre/doc/html/pcre_exec.html +++ /dev/null @@ -1,78 +0,0 @@ - - -pcre_exec specification - - -

pcre_exec man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_exec(const pcre *code, const pcre_extra *extra, -const char *subject, int length, int startoffset, -int options, int *ovector, int ovecsize); -

-
-DESCRIPTION -
-

-This function matches a compiled regular expression against a given subject -string, and returns offsets to capturing subexpressions. Its arguments are: -

-  code         Points to the compiled pattern
-  extra        Points to an associated pcre_extra structure,
-                 or is NULL
-  subject      Points to the subject string
-  length       Length of the subject string, in bytes
-  startoffset  Offset in bytes in the subject at which to
-                 start matching
-  options      Option bits
-  ovector      Points to a vector of ints for result offsets
-  ovecsize     Number of elements in the vector (a multiple of 3)
-
-The options are: -
-  PCRE_ANCHORED      Match only at the first position
-  PCRE_NOTBOL        Subject is not the beginning of a line
-  PCRE_NOTEOL        Subject is not the end of a line
-  PCRE_NOTEMPTY      An empty string is not a valid match
-  PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
-                       validity (only relevant if PCRE_UTF8
-                       was set at compile time)
-  PCRE_PARTIAL       Return PCRE_ERROR_PARTIAL for a partial match
-
-There are restrictions on what may appear in a pattern when partial matching is -requested. -

-

-A pcre_extra structure contains the following fields: -

-  flags        Bits indicating which fields are set
-  study_data   Opaque data from pcre_study()
-  match_limit  Limit on internal recursion
-  callout_data Opaque data passed back to callouts
-  tables       Points to character tables or is NULL
-
-The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, -PCRE_EXTRA_CALLOUT_DATA, and PCRE_EXTRA_TABLES. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_free_substring.html b/srclib/pcre/doc/html/pcre_free_substring.html deleted file mode 100644 index fe6261474c..0000000000 --- a/srclib/pcre/doc/html/pcre_free_substring.html +++ /dev/null @@ -1,40 +0,0 @@ - - -pcre_free_substring specification - - -

pcre_free_substring man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-void pcre_free_substring(const char *stringptr); -

-
-DESCRIPTION -
-

-This is a convenience function for freeing the store obtained by a previous -call to pcre_get_substring() or pcre_get_named_substring(). Its -only argument is a pointer to the string. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_free_substring_list.html b/srclib/pcre/doc/html/pcre_free_substring_list.html deleted file mode 100644 index a92c9603f0..0000000000 --- a/srclib/pcre/doc/html/pcre_free_substring_list.html +++ /dev/null @@ -1,40 +0,0 @@ - - -pcre_free_substring_list specification - - -

pcre_free_substring_list man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-void pcre_free_substring_list(const char **stringptr); -

-
-DESCRIPTION -
-

-This is a convenience function for freeing the store obtained by a previous -call to pcre_get_substring_list(). Its only argument is a pointer to the -list of string pointers. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_fullinfo.html b/srclib/pcre/doc/html/pcre_fullinfo.html deleted file mode 100644 index 3488285c2a..0000000000 --- a/srclib/pcre/doc/html/pcre_fullinfo.html +++ /dev/null @@ -1,71 +0,0 @@ - - -pcre_fullinfo specification - - -

pcre_fullinfo man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_fullinfo(const pcre *code, const pcre_extra *extra, -int what, void *where); -

-
-DESCRIPTION -
-

-This function returns information about a compiled pattern. Its arguments are: -

-  code                      Compiled regular expression
-  extra                     Result of pcre_study() or NULL
-  what                      What information is required
-  where                     Where to put the information
-
-The following information is available: -
-  PCRE_INFO_BACKREFMAX      Number of highest back reference
-  PCRE_INFO_CAPTURECOUNT    Number of capturing subpatterns
-  PCRE_INFO_DEFAULT_TABLES  Pointer to default tables
-  PCRE_INFO_FIRSTBYTE       Fixed first byte for a match, or
-                              -1 for start of string
-                                 or after newline, or
-                              -2 otherwise
-  PCRE_INFO_FIRSTTABLE      Table of first bytes
-                              (after studying)
-  PCRE_INFO_LASTLITERAL     Literal last byte required
-  PCRE_INFO_NAMECOUNT       Number of named subpatterns
-  PCRE_INFO_NAMEENTRYSIZE   Size of name table entry
-  PCRE_INFO_NAMETABLE       Pointer to name table
-  PCRE_INFO_OPTIONS         Options used for compilation
-  PCRE_INFO_SIZE            Size of compiled pattern
-  PCRE_INFO_STUDYSIZE       Size of study data
-
-The yield of the function is zero on success or: -
-  PCRE_ERROR_NULL           the argument code was NULL
-                            the argument where was NULL
-  PCRE_ERROR_BADMAGIC       the "magic number" was not found
-  PCRE_ERROR_BADOPTION      the value of what was invalid
-
-

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_get_named_substring.html b/srclib/pcre/doc/html/pcre_get_named_substring.html deleted file mode 100644 index ff8456bb57..0000000000 --- a/srclib/pcre/doc/html/pcre_get_named_substring.html +++ /dev/null @@ -1,54 +0,0 @@ - - -pcre_get_named_substring specification - - -

pcre_get_named_substring man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_get_named_substring(const pcre *code, -const char *subject, int *ovector, -int stringcount, const char *stringname, -const char **stringptr); -

-
-DESCRIPTION -
-

-This is a convenience function for extracting a captured substring by name. The -arguments are: -

-  code          Compiled pattern
-  subject       Subject that has been successfully matched
-  ovector       Offset vector that pcre_exec() used
-  stringcount   Value returned by pcre_exec()
-  stringname    Name of the required substring
-  stringptr     Where to put the string pointer
-
-The memory in which the substring is placed is obtained by calling -pcre_malloc(). The yield of the function is the length of the extracted -substring, PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or -PCRE_ERROR_NOSUBSTRING if the string name is invalid. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_get_stringnumber.html b/srclib/pcre/doc/html/pcre_get_stringnumber.html deleted file mode 100644 index 9c8bea0b4b..0000000000 --- a/srclib/pcre/doc/html/pcre_get_stringnumber.html +++ /dev/null @@ -1,46 +0,0 @@ - - -pcre_get_stringnumber specification - - -

pcre_get_stringnumber man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_get_stringnumber(const pcre *code, -const char *name); -

-
-DESCRIPTION -
-

-This convenience function finds the number of a named substring capturing -parenthesis in a compiled pattern. Its arguments are: -

-  code    Compiled regular expression
-  name    Name whose number is required
-
-The yield of the function is the number of the parenthesis if the name is -found, or PCRE_ERROR_NOSUBSTRING otherwise. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_get_substring.html b/srclib/pcre/doc/html/pcre_get_substring.html deleted file mode 100644 index 14a413222a..0000000000 --- a/srclib/pcre/doc/html/pcre_get_substring.html +++ /dev/null @@ -1,52 +0,0 @@ - - -pcre_get_substring specification - - -

pcre_get_substring man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_get_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, -const char **stringptr); -

-
-DESCRIPTION -
-

-This is a convenience function for extracting a captured substring. The -arguments are: -

-  subject       Subject that has been successfully matched
-  ovector       Offset vector that pcre_exec() used
-  stringcount   Value returned by pcre_exec()
-  stringnumber  Number of the required substring
-  stringptr     Where to put the string pointer
-
-The memory in which the substring is placed is obtained by calling -pcre_malloc(). The yield of the function is the length of the substring, -PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or -PCRE_ERROR_NOSUBSTRING if the string number is invalid. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_get_substring_list.html b/srclib/pcre/doc/html/pcre_get_substring_list.html deleted file mode 100644 index d278b1793d..0000000000 --- a/srclib/pcre/doc/html/pcre_get_substring_list.html +++ /dev/null @@ -1,51 +0,0 @@ - - -pcre_get_substring_list specification - - -

pcre_get_substring_list man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_get_substring_list(const char *subject, -int *ovector, int stringcount, const char ***listptr); -

-
-DESCRIPTION -
-

-This is a convenience function for extracting a list of all the captured -substrings. The arguments are: -

-  subject       Subject that has been successfully matched
-  ovector       Offset vector that pcre_exec used
-  stringcount   Value returned by pcre_exec
-  listptr       Where to put a pointer to the list
-
-The memory in which the substrings and the list are placed is obtained by -calling pcre_malloc(). A pointer to a list of pointers is put in -the variable whose address is in listptr. The list is terminated by a -NULL pointer. The yield of the function is zero on success or -PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_info.html b/srclib/pcre/doc/html/pcre_info.html deleted file mode 100644 index 6693ffee6c..0000000000 --- a/srclib/pcre/doc/html/pcre_info.html +++ /dev/null @@ -1,39 +0,0 @@ - - -pcre_info specification - - -

pcre_info man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-int pcre_info(const pcre *code, int *optptr, int -*firstcharptr); -

-
-DESCRIPTION -
-

-This function is obsolete. You should be using pcre_fullinfo() instead. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_maketables.html b/srclib/pcre/doc/html/pcre_maketables.html deleted file mode 100644 index cf8d69ecfd..0000000000 --- a/srclib/pcre/doc/html/pcre_maketables.html +++ /dev/null @@ -1,42 +0,0 @@ - - -pcre_maketables specification - - -

pcre_maketables man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-const unsigned char *pcre_maketables(void); -

-
-DESCRIPTION -
-

-This function builds a set of character tables for character values less than -256. These can be passed to pcre_compile() to override PCRE's internal, -built-in tables (which were made by pcre_maketables() when PCRE was -compiled). You might want to do this if you are using a non-standard locale. -The function yields a pointer to the tables. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_study.html b/srclib/pcre/doc/html/pcre_study.html deleted file mode 100644 index d290420e54..0000000000 --- a/srclib/pcre/doc/html/pcre_study.html +++ /dev/null @@ -1,56 +0,0 @@ - - -pcre_study specification - - -

pcre_study man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-pcre_extra *pcre_study(const pcre *code, int options, -const char **errptr); -

-
-DESCRIPTION -
-

-This function studies a compiled pattern, to see if additional information can -be extracted that might speed up matching. Its arguments are: -

-  code       A compiled regular expression
-  options    Options for pcre_study()
-  errptr     Where to put an error message
-
-If the function succeeds, it returns a value that can be passed to -pcre_exec() via its extra argument. -

-

-If the function returns NULL, either it could not find any additional -information, or there was an error. You can tell the difference by looking at -the error value. It is NULL in first case. -

-

-There are currently no options defined; the value of the second argument should -always be zero. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcre_version.html b/srclib/pcre/doc/html/pcre_version.html deleted file mode 100644 index 7bc8f8653e..0000000000 --- a/srclib/pcre/doc/html/pcre_version.html +++ /dev/null @@ -1,39 +0,0 @@ - - -pcre_version specification - - -

pcre_version man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-SYNOPSIS -
-

-#include <pcre.h> -

-

-char *pcre_version(void); -

-
-DESCRIPTION -
-

-This function returns a character string that gives the version number of the -PCRE library and the date of its release. -

-

-There is a complete description of the PCRE native API in the -pcreapi -page and a description of the POSIX API in the -pcreposix -page. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcreapi.html b/srclib/pcre/doc/html/pcreapi.html deleted file mode 100644 index 72639f4cc3..0000000000 --- a/srclib/pcre/doc/html/pcreapi.html +++ /dev/null @@ -1,1287 +0,0 @@ - - -pcreapi specification - - -

pcreapi man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
PCRE NATIVE API
-

-#include <pcre.h> -

-

-pcre *pcre_compile(const char *pattern, int options, -const char **errptr, int *erroffset, -const unsigned char *tableptr); -

-

-pcre_extra *pcre_study(const pcre *code, int options, -const char **errptr); -

-

-int pcre_exec(const pcre *code, const pcre_extra *extra, -const char *subject, int length, int startoffset, -int options, int *ovector, int ovecsize); -

-

-int pcre_copy_named_substring(const pcre *code, -const char *subject, int *ovector, -int stringcount, const char *stringname, -char *buffer, int buffersize); -

-

-int pcre_copy_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, char *buffer, -int buffersize); -

-

-int pcre_get_named_substring(const pcre *code, -const char *subject, int *ovector, -int stringcount, const char *stringname, -const char **stringptr); -

-

-int pcre_get_stringnumber(const pcre *code, -const char *name); -

-

-int pcre_get_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, -const char **stringptr); -

-

-int pcre_get_substring_list(const char *subject, -int *ovector, int stringcount, const char ***listptr); -

-

-void pcre_free_substring(const char *stringptr); -

-

-void pcre_free_substring_list(const char **stringptr); -

-

-const unsigned char *pcre_maketables(void); -

-

-int pcre_fullinfo(const pcre *code, const pcre_extra *extra, -int what, void *where); -

-

-int pcre_info(const pcre *code, int *optptr, int -*firstcharptr); -

-

-int pcre_config(int what, void *where); -

-

-char *pcre_version(void); -

-

-void *(*pcre_malloc)(size_t); -

-

-void (*pcre_free)(void *); -

-

-void *(*pcre_stack_malloc)(size_t); -

-

-void (*pcre_stack_free)(void *); -

-

-int (*pcre_callout)(pcre_callout_block *); -

-
PCRE API OVERVIEW
-

-PCRE has its own native API, which is described in this document. There is also -a set of wrapper functions that correspond to the POSIX regular expression API. -These are described in the -pcreposix -documentation. -

-

-The native API function prototypes are defined in the header file pcre.h, -and on Unix systems the library itself is called libpcre. It can -normally be accessed by adding -lpcre to the command for linking an -application that uses PCRE. The header file defines the macros PCRE_MAJOR and -PCRE_MINOR to contain the major and minor release numbers for the library. -Applications can use these to include support for different releases of PCRE. -

-

-The functions pcre_compile(), pcre_study(), and pcre_exec() -are used for compiling and matching regular expressions. A sample program that -demonstrates the simplest way of using them is provided in the file called -pcredemo.c in the source distribution. The -pcresample -documentation describes how to run it. -

-

-In addition to the main compiling and matching functions, there are convenience -functions for extracting captured substrings from a matched subject string. -They are: -

-  pcre_copy_substring()
-  pcre_copy_named_substring()
-  pcre_get_substring()
-  pcre_get_named_substring()
-  pcre_get_substring_list()
-  pcre_get_stringnumber()
-
-pcre_free_substring() and pcre_free_substring_list() are also -provided, to free the memory used for extracted strings. -

-

-The function pcre_maketables() is used to build a set of character tables -in the current locale for passing to pcre_compile() or pcre_exec(). -This is an optional facility that is provided for specialist use. Most -commonly, no special tables are passed, in which case internal tables that are -generated when PCRE is built are used. -

-

-The function pcre_fullinfo() is used to find out information about a -compiled pattern; pcre_info() is an obsolete version that returns only -some of the available information, but is retained for backwards compatibility. -The function pcre_version() returns a pointer to a string containing the -version of PCRE and its date of release. -

-

-The global variables pcre_malloc and pcre_free initially contain -the entry points of the standard malloc() and free() functions, -respectively. PCRE calls the memory management functions via these variables, -so a calling program can replace them if it wishes to intercept the calls. This -should be done before calling any PCRE functions. -

-

-The global variables pcre_stack_malloc and pcre_stack_free are also -indirections to memory management functions. These special functions are used -only when PCRE is compiled to use the heap for remembering data, instead of -recursive function calls. This is a non-standard way of building PCRE, for use -in environments that have limited stacks. Because of the greater use of memory -management, it runs more slowly. Separate functions are provided so that -special-purpose external code can be used for this case. When used, these -functions are always called in a stack-like manner (last obtained, first -freed), and always for memory blocks of the same size. -

-

-The global variable pcre_callout initially contains NULL. It can be set -by the caller to a "callout" function, which PCRE will then call at specified -points during a matching operation. Details are given in the -pcrecallout -documentation. -

-
MULTITHREADING
-

-The PCRE functions can be used in multi-threading applications, with the -proviso that the memory management functions pointed to by pcre_malloc, -pcre_free, pcre_stack_malloc, and pcre_stack_free, and the -callout function pointed to by pcre_callout, are shared by all threads. -

-

-The compiled form of a regular expression is not altered during matching, so -the same compiled pattern can safely be used by several threads at once. -

-
SAVING PRECOMPILED PATTERNS FOR LATER USE
-

-The compiled form of a regular expression can be saved and re-used at a later -time, possibly by a different program, and even on a host other than the one on -which it was compiled. Details are given in the -pcreprecompile -documentation. -

-
CHECKING BUILD-TIME OPTIONS
-

-int pcre_config(int what, void *where); -

-

-The function pcre_config() makes it possible for a PCRE client to -discover which optional features have been compiled into the PCRE library. The -pcrebuild -documentation has more details about these optional features. -

-

-The first argument for pcre_config() is an integer, specifying which -information is required; the second argument is a pointer to a variable into -which the information is placed. The following information is available: -

-  PCRE_CONFIG_UTF8
-
-The output is an integer that is set to one if UTF-8 support is available; -otherwise it is set to zero. -
-  PCRE_CONFIG_UNICODE_PROPERTIES
-
-The output is an integer that is set to one if support for Unicode character -properties is available; otherwise it is set to zero. -
-  PCRE_CONFIG_NEWLINE
-
-The output is an integer that is set to the value of the code that is used for -the newline character. It is either linefeed (10) or carriage return (13), and -should normally be the standard character for your operating system. -
-  PCRE_CONFIG_LINK_SIZE
-
-The output is an integer that contains the number of bytes used for internal -linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values -allow larger regular expressions to be compiled, at the expense of slower -matching. The default value of 2 is sufficient for all but the most massive -patterns, since it allows the compiled pattern to be up to 64K in size. -
-  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
-
-The output is an integer that contains the threshold above which the POSIX -interface uses malloc() for output vectors. Further details are given in -the -pcreposix -documentation. -
-  PCRE_CONFIG_MATCH_LIMIT
-
-The output is an integer that gives the default limit for the number of -internal matching function calls in a pcre_exec() execution. Further -details are given with pcre_exec() below. -
-  PCRE_CONFIG_STACKRECURSE
-
-The output is an integer that is set to one if internal recursion is -implemented by recursive function calls that use the stack to remember their -state. This is the usual way that PCRE is compiled. The output is zero if PCRE -was compiled to use blocks of data on the heap instead of recursive function -calls. In this case, pcre_stack_malloc and pcre_stack_free are -called to manage memory blocks on the heap, thus avoiding the use of the stack. -

-
COMPILING A PATTERN
-

-pcre *pcre_compile(const char *pattern, int options, -const char **errptr, int *erroffset, -const unsigned char *tableptr); -

-

-The function pcre_compile() is called to compile a pattern into an -internal form. The pattern is a C string terminated by a binary zero, and -is passed in the pattern argument. A pointer to a single block of memory -that is obtained via pcre_malloc is returned. This contains the compiled -code and related data. The pcre type is defined for the returned block; -this is a typedef for a structure whose contents are not externally defined. It -is up to the caller to free the memory when it is no longer required. -

-

-Although the compiled code of a PCRE regex is relocatable, that is, it does not -depend on memory location, the complete pcre data block is not -fully relocatable, because it may contain a copy of the tableptr -argument, which is an address (see below). -

-

-The options argument contains independent bits that affect the -compilation. It should be zero if no options are required. The available -options are described below. Some of them, in particular, those that are -compatible with Perl, can also be set and unset from within the pattern (see -the detailed description in the -pcrepattern -documentation). For these options, the contents of the options argument -specifies their initial settings at the start of compilation and execution. The -PCRE_ANCHORED option can be set at the time of matching as well as at compile -time. -

-

-If errptr is NULL, pcre_compile() returns NULL immediately. -Otherwise, if compilation of a pattern fails, pcre_compile() returns -NULL, and sets the variable pointed to by errptr to point to a textual -error message. The offset from the start of the pattern to the character where -the error was discovered is placed in the variable pointed to by -erroffset, which must not be NULL. If it is, an immediate error is given. -

-

-If the final argument, tableptr, is NULL, PCRE uses a default set of -character tables that are built when PCRE is compiled, using the default C -locale. Otherwise, tableptr must be an address that is the result of a -call to pcre_maketables(). This value is stored with the compiled -pattern, and used again by pcre_exec(), unless another table pointer is -passed to it. For more discussion, see the section on locale support below. -

-

-This code fragment shows a typical straightforward call to pcre_compile(): -

-  pcre *re;
-  const char *error;
-  int erroffset;
-  re = pcre_compile(
-    "^A.*Z",          /* the pattern */
-    0,                /* default options */
-    &error,           /* for error message */
-    &erroffset,       /* for error offset */
-    NULL);            /* use default character tables */
-
-The following names for option bits are defined in the pcre.h header -file: -
-  PCRE_ANCHORED
-
-If this bit is set, the pattern is forced to be "anchored", that is, it is -constrained to match only at the first matching point in the string that is -being searched (the "subject string"). This effect can also be achieved by -appropriate constructs in the pattern itself, which is the only way to do it in -Perl. -
-  PCRE_AUTO_CALLOUT
-
-If this bit is set, pcre_compile() automatically inserts callout items, -all with number 255, before each pattern item. For discussion of the callout -facility, see the -pcrecallout -documentation. -
-  PCRE_CASELESS
-
-If this bit is set, letters in the pattern match both upper and lower case -letters. It is equivalent to Perl's /i option, and it can be changed within a -pattern by a (?i) option setting. When running in UTF-8 mode, case support for -high-valued characters is available only when PCRE is built with Unicode -character property support. -
-  PCRE_DOLLAR_ENDONLY
-
-If this bit is set, a dollar metacharacter in the pattern matches only at the -end of the subject string. Without this option, a dollar also matches -immediately before the final character if it is a newline (but not before any -other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is -set. There is no equivalent to this option in Perl, and no way to set it within -a pattern. -
-  PCRE_DOTALL
-
-If this bit is set, a dot metacharater in the pattern matches all characters, -including newlines. Without it, newlines are excluded. This option is -equivalent to Perl's /s option, and it can be changed within a pattern by a -(?s) option setting. A negative class such as [^a] always matches a newline -character, independent of the setting of this option. -
-  PCRE_EXTENDED
-
-If this bit is set, whitespace data characters in the pattern are totally -ignored except when escaped or inside a character class. Whitespace does not -include the VT character (code 11). In addition, characters between an -unescaped # outside a character class and the next newline character, -inclusive, are also ignored. This is equivalent to Perl's /x option, and it can -be changed within a pattern by a (?x) option setting. -

-

-This option makes it possible to include comments inside complicated patterns. -Note, however, that this applies only to data characters. Whitespace characters -may never appear within special character sequences in a pattern, for example -within the sequence (?( which introduces a conditional subpattern. -

-  PCRE_EXTRA
-
-This option was invented in order to turn on additional functionality of PCRE -that is incompatible with Perl, but it is currently of very little use. When -set, any backslash in a pattern that is followed by a letter that has no -special meaning causes an error, thus reserving these combinations for future -expansion. By default, as in Perl, a backslash followed by a letter with no -special meaning is treated as a literal. There are at present no other features -controlled by this option. It can also be set by a (?X) option setting within a -pattern. -
-  PCRE_MULTILINE
-
-By default, PCRE treats the subject string as consisting of a single line of -characters (even if it actually contains newlines). The "start of line" -metacharacter (^) matches only at the start of the string, while the "end of -line" metacharacter ($) matches only at the end of the string, or before a -terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as -Perl. -

-

-When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs -match immediately following or immediately before any newline in the subject -string, respectively, as well as at the very start and end. This is equivalent -to Perl's /m option, and it can be changed within a pattern by a (?m) option -setting. If there are no "\n" characters in a subject string, or no -occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect. -

-  PCRE_NO_AUTO_CAPTURE
-
-If this option is set, it disables the use of numbered capturing parentheses in -the pattern. Any opening parenthesis that is not followed by ? behaves as if it -were followed by ?: but named parentheses can still be used for capturing (and -they acquire numbers in the usual way). There is no equivalent of this option -in Perl. -
-  PCRE_UNGREEDY
-
-This option inverts the "greediness" of the quantifiers so that they are not -greedy by default, but become greedy if followed by "?". It is not compatible -with Perl. It can also be set by a (?U) option setting within the pattern. -
-  PCRE_UTF8
-
-This option causes PCRE to regard both the pattern and the subject as strings -of UTF-8 characters instead of single-byte character strings. However, it is -available only when PCRE is built to include UTF-8 support. If not, the use -of this option provokes an error. Details of how this option changes the -behaviour of PCRE are given in the -section on UTF-8 support -in the main -pcre -page. -
-  PCRE_NO_UTF8_CHECK
-
-When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is -automatically checked. If an invalid UTF-8 sequence of bytes is found, -pcre_compile() returns an error. If you already know that your pattern is -valid, and you want to skip this check for performance reasons, you can set the -PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid -UTF-8 string as a pattern is undefined. It may cause your program to crash. -Note that this option can also be passed to pcre_exec(), to suppress the -UTF-8 validity checking of subject strings. -

-
STUDYING A PATTERN
-

-pcre_extra *pcre_study(const pcre *code, int options, -const char **errptr); -

-

-If a compiled pattern is going to be used several times, it is worth spending -more time analyzing it in order to speed up the time taken for matching. The -function pcre_study() takes a pointer to a compiled pattern as its first -argument. If studying the pattern produces additional information that will -help speed up matching, pcre_study() returns a pointer to a -pcre_extra block, in which the study_data field points to the -results of the study. -

-

-The returned value from pcre_study() can be passed directly to -pcre_exec(). However, a pcre_extra block also contains other -fields that can be set by the caller before the block is passed; these are -described -below -in the section on matching a pattern. -

-

-If studying the pattern does not produce any additional information, -pcre_study() returns NULL. In that circumstance, if the calling program -wants to pass any of the other fields to pcre_exec(), it must set up its -own pcre_extra block. -

-

-The second argument of pcre_study() contains option bits. At present, no -options are defined, and this argument should always be zero. -

-

-The third argument for pcre_study() is a pointer for an error message. If -studying succeeds (even if no data is returned), the variable it points to is -set to NULL. Otherwise it points to a textual error message. You should -therefore test the error pointer for NULL after calling pcre_study(), to -be sure that it has run successfully. -

-

-This is a typical call to pcre_study(): -

-  pcre_extra *pe;
-  pe = pcre_study(
-    re,             /* result of pcre_compile() */
-    0,              /* no options exist */
-    &error);        /* set to NULL or points to a message */
-
-At present, studying a pattern is useful only for non-anchored patterns that do -not have a single fixed starting character. A bitmap of possible starting -bytes is created. -

-
LOCALE SUPPORT
-

-PCRE handles caseless matching, and determines whether characters are letters, -digits, or whatever, by reference to a set of tables, indexed by character -value. (When running in UTF-8 mode, this applies only to characters with codes -less than 128. Higher-valued codes never match escapes such as \w or \d, but -can be tested with \p if PCRE is built with Unicode character property -support.) -

-

-An internal set of tables is created in the default C locale when PCRE is -built. This is used when the final argument of pcre_compile() is NULL, -and is sufficient for many applications. An alternative set of tables can, -however, be supplied. These may be created in a different locale from the -default. As more and more applications change to using Unicode, the need for -this locale support is expected to die away. -

-

-External tables are built by calling the pcre_maketables() function, -which has no arguments, in the relevant locale. The result can then be passed -to pcre_compile() or pcre_exec() as often as necessary. For -example, to build and use tables that are appropriate for the French locale -(where accented characters with values greater than 128 are treated as letters), -the following code could be used: -

-  setlocale(LC_CTYPE, "fr_FR");
-  tables = pcre_maketables();
-  re = pcre_compile(..., tables);
-
-When pcre_maketables() runs, the tables are built in memory that is -obtained via pcre_malloc. It is the caller's responsibility to ensure -that the memory containing the tables remains available for as long as it is -needed. -

-

-The pointer that is passed to pcre_compile() is saved with the compiled -pattern, and the same tables are used via this pointer by pcre_study() -and normally also by pcre_exec(). Thus, by default, for any single -pattern, compilation, studying and matching all happen in the same locale, but -different patterns can be compiled in different locales. -

-

-It is possible to pass a table pointer or NULL (indicating the use of the -internal tables) to pcre_exec(). Although not intended for this purpose, -this facility could be used to match a pattern in a different locale from the -one in which it was compiled. Passing table pointers at run time is discussed -below in the section on matching a pattern. -

-
INFORMATION ABOUT A PATTERN
-

-int pcre_fullinfo(const pcre *code, const pcre_extra *extra, -int what, void *where); -

-

-The pcre_fullinfo() function returns information about a compiled -pattern. It replaces the obsolete pcre_info() function, which is -nevertheless retained for backwards compability (and is documented below). -

-

-The first argument for pcre_fullinfo() is a pointer to the compiled -pattern. The second argument is the result of pcre_study(), or NULL if -the pattern was not studied. The third argument specifies which piece of -information is required, and the fourth argument is a pointer to a variable -to receive the data. The yield of the function is zero for success, or one of -the following negative numbers: -

-  PCRE_ERROR_NULL       the argument code was NULL
-                        the argument where was NULL
-  PCRE_ERROR_BADMAGIC   the "magic number" was not found
-  PCRE_ERROR_BADOPTION  the value of what was invalid
-
-The "magic number" is placed at the start of each compiled pattern as an simple -check against passing an arbitrary memory pointer. Here is a typical call of -pcre_fullinfo(), to obtain the length of the compiled pattern: -
-  int rc;
-  unsigned long int length;
-  rc = pcre_fullinfo(
-    re,               /* result of pcre_compile() */
-    pe,               /* result of pcre_study(), or NULL */
-    PCRE_INFO_SIZE,   /* what is required */
-    &length);         /* where to put the data */
-
-The possible values for the third argument are defined in pcre.h, and are -as follows: -
-  PCRE_INFO_BACKREFMAX
-
-Return the number of the highest back reference in the pattern. The fourth -argument should point to an int variable. Zero is returned if there are -no back references. -
-  PCRE_INFO_CAPTURECOUNT
-
-Return the number of capturing subpatterns in the pattern. The fourth argument -should point to an int variable. -
-  PCRE_INFO_DEFAULTTABLES
-
-Return a pointer to the internal default character tables within PCRE. The -fourth argument should point to an unsigned char * variable. This -information call is provided for internal use by the pcre_study() -function. External callers can cause PCRE to use its internal tables by passing -a NULL table pointer. -
-  PCRE_INFO_FIRSTBYTE
-
-Return information about the first byte of any matched string, for a -non-anchored pattern. (This option used to be called PCRE_INFO_FIRSTCHAR; the -old name is still recognized for backwards compatibility.) -

-

-If there is a fixed first byte, for example, from a pattern such as -(cat|cow|coyote), it is returned in the integer pointed to by where. -Otherwise, if either -
-
-(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch -starts with "^", or -
-
-(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set -(if it were set, the pattern would be anchored), -
-
--1 is returned, indicating that the pattern matches only at the start of a -subject string or after any newline within the string. Otherwise -2 is -returned. For anchored patterns, -2 is returned. -

-  PCRE_INFO_FIRSTTABLE
-
-If the pattern was studied, and this resulted in the construction of a 256-bit -table indicating a fixed set of bytes for the first byte in any matching -string, a pointer to the table is returned. Otherwise NULL is returned. The -fourth argument should point to an unsigned char * variable. -
-  PCRE_INFO_LASTLITERAL
-
-Return the value of the rightmost literal byte that must exist in any matched -string, other than at its start, if such a byte has been recorded. The fourth -argument should point to an int variable. If there is no such byte, -1 is -returned. For anchored patterns, a last literal byte is recorded only if it -follows something of variable length. For example, for the pattern -/^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value -is -1. -
-  PCRE_INFO_NAMECOUNT
-  PCRE_INFO_NAMEENTRYSIZE
-  PCRE_INFO_NAMETABLE
-
-PCRE supports the use of named as well as numbered capturing parentheses. The -names are just an additional way of identifying the parentheses, which still -acquire numbers. A convenience function called pcre_get_named_substring() -is provided for extracting an individual captured substring by name. It is also -possible to extract the data directly, by first converting the name to a number -in order to access the correct pointers in the output vector (described with -pcre_exec() below). To do the conversion, you need to use the -name-to-number map, which is described by these three values. -

-

-The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives -the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each -entry; both of these return an int value. The entry size depends on the -length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first -entry of the table (a pointer to char). The first two bytes of each entry -are the number of the capturing parenthesis, most significant byte first. The -rest of the entry is the corresponding name, zero terminated. The names are in -alphabetical order. For example, consider the following pattern (assume -PCRE_EXTENDED is set, so white space - including newlines - is ignored): -

-  (?P<date> (?P<year>(\d\d)?\d\d) - (?P<month>\d\d) - (?P<day>\d\d) )
-
-There are four named subpatterns, so the table has four entries, and each entry -in the table is eight bytes long. The table is as follows, with non-printing -bytes shows in hexadecimal, and undefined bytes shown as ??: -
-  00 01 d  a  t  e  00 ??
-  00 05 d  a  y  00 ?? ??
-  00 04 m  o  n  t  h  00
-  00 02 y  e  a  r  00 ??
-
-When writing code to extract data from named subpatterns using the -name-to-number map, remember that the length of each entry is likely to be -different for each compiled pattern. -
-  PCRE_INFO_OPTIONS
-
-Return a copy of the options with which the pattern was compiled. The fourth -argument should point to an unsigned long int variable. These option bits -are those specified in the call to pcre_compile(), modified by any -top-level option settings within the pattern itself. -

-

-A pattern is automatically anchored by PCRE if all of its top-level -alternatives begin with one of the following: -

-  ^     unless PCRE_MULTILINE is set
-  \A    always
-  \G    always
-  .*    if PCRE_DOTALL is set and there are no back references to the subpattern in which .* appears
-
-For such patterns, the PCRE_ANCHORED bit is set in the options returned by -pcre_fullinfo(). -
-  PCRE_INFO_SIZE
-
-Return the size of the compiled pattern, that is, the value that was passed as -the argument to pcre_malloc() when PCRE was getting memory in which to -place the compiled data. The fourth argument should point to a size_t -variable. -
-  PCRE_INFO_STUDYSIZE
-
-Return the size of the data block pointed to by the study_data field in -a pcre_extra block. That is, it is the value that was passed to -pcre_malloc() when PCRE was getting memory into which to place the data -created by pcre_study(). The fourth argument should point to a -size_t variable. -

-
OBSOLETE INFO FUNCTION
-

-int pcre_info(const pcre *code, int *optptr, int -*firstcharptr); -

-

-The pcre_info() function is now obsolete because its interface is too -restrictive to return all the available data about a compiled pattern. New -programs should use pcre_fullinfo() instead. The yield of -pcre_info() is the number of capturing subpatterns, or one of the -following negative numbers: -

-  PCRE_ERROR_NULL       the argument code was NULL
-  PCRE_ERROR_BADMAGIC   the "magic number" was not found
-
-If the optptr argument is not NULL, a copy of the options with which the -pattern was compiled is placed in the integer it points to (see -PCRE_INFO_OPTIONS above). -

-

-If the pattern is not anchored and the firstcharptr argument is not NULL, -it is used to pass back information about the first character of any matched -string (see PCRE_INFO_FIRSTBYTE above). -

-
MATCHING A PATTERN
-

-int pcre_exec(const pcre *code, const pcre_extra *extra, -const char *subject, int length, int startoffset, -int options, int *ovector, int ovecsize); -

-

-The function pcre_exec() is called to match a subject string against a -compiled pattern, which is passed in the code argument. If the -pattern has been studied, the result of the study should be passed in the -extra argument. -

-

-In most applications, the pattern will have been compiled (and optionally -studied) in the same process that calls pcre_exec(). However, it is -possible to save compiled patterns and study data, and then use them later -in different processes, possibly even on different hosts. For a discussion -about this, see the -pcreprecompile -documentation. -

-

-Here is an example of a simple call to pcre_exec(): -

-  int rc;
-  int ovector[30];
-  rc = pcre_exec(
-    re,             /* result of pcre_compile() */
-    NULL,           /* we didn't study the pattern */
-    "some string",  /* the subject string */
-    11,             /* the length of the subject string */
-    0,              /* start at offset 0 in the subject */
-    0,              /* default options */
-    ovector,        /* vector of integers for substring information */
-    30);            /* number of elements in the vector (NOT size in bytes) */
-
-

-
-Extra data for pcre_exec() -
-

-If the extra argument is not NULL, it must point to a pcre_extra -data block. The pcre_study() function returns such a block (when it -doesn't return NULL), but you can also create one for yourself, and pass -additional information in it. The fields in a pcre_extra block are as -follows: -

-  unsigned long int flags;
-  void *study_data;
-  unsigned long int match_limit;
-  void *callout_data;
-  const unsigned char *tables;
-
-The flags field is a bitmap that specifies which of the other fields -are set. The flag bits are: -
-  PCRE_EXTRA_STUDY_DATA
-  PCRE_EXTRA_MATCH_LIMIT
-  PCRE_EXTRA_CALLOUT_DATA
-  PCRE_EXTRA_TABLES
-
-Other flag bits should be set to zero. The study_data field is set in the -pcre_extra block that is returned by pcre_study(), together with -the appropriate flag bit. You should not set this yourself, but you may add to -the block by setting the other fields and their corresponding flag bits. -

-

-The match_limit field provides a means of preventing PCRE from using up a -vast amount of resources when running patterns that are not going to match, -but which have a very large number of possibilities in their search trees. The -classic example is the use of nested unlimited repeats. -

-

-Internally, PCRE uses a function called match() which it calls repeatedly -(sometimes recursively). The limit is imposed on the number of times this -function is called during a match, which has the effect of limiting the amount -of recursion and backtracking that can take place. For patterns that are not -anchored, the count starts from zero for each position in the subject string. -

-

-The default limit for the library can be set when PCRE is built; the default -default is 10 million, which handles all but the most extreme cases. You can -reduce the default by suppling pcre_exec() with a pcre_extra block -in which match_limit is set to a smaller value, and -PCRE_EXTRA_MATCH_LIMIT is set in the flags field. If the limit is -exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT. -

-

-The pcre_callout field is used in conjunction with the "callout" feature, -which is described in the -pcrecallout -documentation. -

-

-The tables field is used to pass a character tables pointer to -pcre_exec(); this overrides the value that is stored with the compiled -pattern. A non-NULL value is stored with the compiled pattern only if custom -tables were supplied to pcre_compile() via its tableptr argument. -If NULL is passed to pcre_exec() using this mechanism, it forces PCRE's -internal tables to be used. This facility is helpful when re-using patterns -that have been saved after compiling with an external set of tables, because -the external tables might be at a different address when pcre_exec() is -called. See the -pcreprecompile -documentation for a discussion of saving compiled patterns for later use. -

-
-Option bits for pcre_exec() -
-

-The unused bits of the options argument for pcre_exec() must be -zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NOTBOL, -PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL. -

-  PCRE_ANCHORED
-
-The PCRE_ANCHORED option limits pcre_exec() to matching at the first -matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out -to be anchored by virtue of its contents, it cannot be made unachored at -matching time. -
-  PCRE_NOTBOL
-
-This option specifies that first character of the subject string is not the -beginning of a line, so the circumflex metacharacter should not match before -it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex -never to match. This option affects only the behaviour of the circumflex -metacharacter. It does not affect \A. -
-  PCRE_NOTEOL
-
-This option specifies that the end of the subject string is not the end of a -line, so the dollar metacharacter should not match it nor (except in multiline -mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at -compile time) causes dollar never to match. This option affects only the -behaviour of the dollar metacharacter. It does not affect \Z or \z. -
-  PCRE_NOTEMPTY
-
-An empty string is not considered to be a valid match if this option is set. If -there are alternatives in the pattern, they are tried. If all the alternatives -match the empty string, the entire match fails. For example, if the pattern -
-  a?b?
-
-is applied to a string not beginning with "a" or "b", it matches the empty -string at the start of the subject. With PCRE_NOTEMPTY set, this match is not -valid, so PCRE searches further into the string for occurrences of "a" or "b". -

-

-Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case -of a pattern match of the empty string within its split() function, and -when using the /g modifier. It is possible to emulate Perl's behaviour after -matching a null string by first trying the match again at the same offset with -PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the -starting offset (see below) and trying an ordinary match again. There is some -code that demonstrates how to do this in the pcredemo.c sample program. -

-  PCRE_NO_UTF8_CHECK
-
-When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8 -string is automatically checked when pcre_exec() is subsequently called. -The value of startoffset is also checked to ensure that it points to the -start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found, -pcre_exec() returns the error PCRE_ERROR_BADUTF8. If startoffset -contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned. -

-

-If you already know that your subject is valid, and you want to skip these -checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when -calling pcre_exec(). You might want to do this for the second and -subsequent calls to pcre_exec() if you are making repeated calls to find -all the matches in a single subject string. However, you should be sure that -the value of startoffset points to the start of a UTF-8 character. When -PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a -subject, or a value of startoffset that does not point to the start of a -UTF-8 character, is undefined. Your program may crash. -

-  PCRE_PARTIAL
-
-This option turns on the partial matching feature. If the subject string fails -to match the pattern, but at some point during the matching process the end of -the subject was reached (that is, the subject partially matches the pattern and -the failure to match occurred only because there were not enough subject -characters), pcre_exec() returns PCRE_ERROR_PARTIAL instead of -PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what -may appear in the pattern. These are discussed in the -pcrepartial -documentation. -

-
-The string to be matched by pcre_exec() -
-

-The subject string is passed to pcre_exec() as a pointer in -subject, a length in length, and a starting byte offset in -startoffset. In UTF-8 mode, the byte offset must point to the start of a -UTF-8 character. Unlike the pattern string, the subject may contain binary zero -bytes. When the starting offset is zero, the search for a match starts at the -beginning of the subject, and this is by far the most common case. -

-

-A non-zero starting offset is useful when searching for another match in the -same subject by calling pcre_exec() again after a previous success. -Setting startoffset differs from just passing over a shortened string and -setting PCRE_NOTBOL in the case of a pattern that begins with any kind of -lookbehind. For example, consider the pattern -

-  \Biss\B
-
-which finds occurrences of "iss" in the middle of words. (\B matches only if -the current position in the subject is not a word boundary.) When applied to -the string "Mississipi" the first call to pcre_exec() finds the first -occurrence. If pcre_exec() is called again with just the remainder of the -subject, namely "issipi", it does not match, because \B is always false at the -start of the subject, which is deemed to be a word boundary. However, if -pcre_exec() is passed the entire string again, but with startoffset -set to 4, it finds the second occurrence of "iss" because it is able to look -behind the starting point to discover that it is preceded by a letter. -

-

-If a non-zero starting offset is passed when the pattern is anchored, one -attempt to match at the given offset is made. This can only succeed if the -pattern does not require the match to be at the start of the subject. -

-
-How pcre_exec() returns captured substrings -
-

-In general, a pattern matches a certain portion of the subject, and in -addition, further substrings from the subject may be picked out by parts of the -pattern. Following the usage in Jeffrey Friedl's book, this is called -"capturing" in what follows, and the phrase "capturing subpattern" is used for -a fragment of a pattern that picks out a substring. PCRE supports several other -kinds of parenthesized subpattern that do not cause substrings to be captured. -

-

-Captured substrings are returned to the caller via a vector of integer offsets -whose address is passed in ovector. The number of elements in the vector -is passed in ovecsize, which must be a non-negative number. Note: -this argument is NOT the size of ovector in bytes. -

-

-The first two-thirds of the vector is used to pass back captured substrings, -each substring using a pair of integers. The remaining third of the vector is -used as workspace by pcre_exec() while matching capturing subpatterns, -and is not available for passing back information. The length passed in -ovecsize should always be a multiple of three. If it is not, it is -rounded down. -

-

-When a match is successful, information about captured substrings is returned -in pairs of integers, starting at the beginning of ovector, and -continuing up to two-thirds of its length at the most. The first element of a -pair is set to the offset of the first character in a substring, and the second -is set to the offset of the first character after the end of a substring. The -first pair, ovector[0] and ovector[1], identify the portion of the -subject string matched by the entire pattern. The next pair is used for the -first capturing subpattern, and so on. The value returned by pcre_exec() -is the number of pairs that have been set. If there are no capturing -subpatterns, the return value from a successful match is 1, indicating that -just the first pair of offsets has been set. -

-

-Some convenience functions are provided for extracting the captured substrings -as separate strings. These are described in the following section. -

-

-It is possible for an capturing subpattern number n+1 to match some -part of the subject when subpattern n has not been used at all. For -example, if the string "abc" is matched against the pattern (a|(z))(bc) -subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset -values corresponding to the unused subpattern are set to -1. -

-

-If a capturing subpattern is matched repeatedly, it is the last portion of the -string that it matched that is returned. -

-

-If the vector is too small to hold all the captured substring offsets, it is -used as far as possible (up to two-thirds of its length), and the function -returns a value of zero. In particular, if the substring offsets are not of -interest, pcre_exec() may be called with ovector passed as NULL and -ovecsize as zero. However, if the pattern contains back references and -the ovector is not big enough to remember the related substrings, PCRE -has to get additional memory for use during matching. Thus it is usually -advisable to supply an ovector. -

-

-Note that pcre_info() can be used to find out how many capturing -subpatterns there are in a compiled pattern. The smallest size for -ovector that will allow for n captured substrings, in addition to -the offsets of the substring matched by the whole pattern, is (n+1)*3. -

-
-Return values from pcre_exec() -
-

-If pcre_exec() fails, it returns a negative number. The following are -defined in the header file: -

-  PCRE_ERROR_NOMATCH        (-1)
-
-The subject string did not match the pattern. -
-  PCRE_ERROR_NULL           (-2)
-
-Either code or subject was passed as NULL, or ovector was -NULL and ovecsize was not zero. -
-  PCRE_ERROR_BADOPTION      (-3)
-
-An unrecognized bit was set in the options argument. -
-  PCRE_ERROR_BADMAGIC       (-4)
-
-PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch -the case when it is passed a junk pointer and to detect when a pattern that was -compiled in an environment of one endianness is run in an environment with the -other endianness. This is the error that PCRE gives when the magic number is -not present. -
-  PCRE_ERROR_UNKNOWN_NODE   (-5)
-
-While running the pattern match, an unknown item was encountered in the -compiled pattern. This error could be caused by a bug in PCRE or by overwriting -of the compiled pattern. -
-  PCRE_ERROR_NOMEMORY       (-6)
-
-If a pattern contains back references, but the ovector that is passed to -pcre_exec() is not big enough to remember the referenced substrings, PCRE -gets a block of memory at the start of matching to use for this purpose. If the -call via pcre_malloc() fails, this error is given. The memory is -automatically freed at the end of matching. -
-  PCRE_ERROR_NOSUBSTRING    (-7)
-
-This error is used by the pcre_copy_substring(), -pcre_get_substring(), and pcre_get_substring_list() functions (see -below). It is never returned by pcre_exec(). -
-  PCRE_ERROR_MATCHLIMIT     (-8)
-
-The recursion and backtracking limit, as specified by the match_limit -field in a pcre_extra structure (or defaulted) was reached. See the -description above. -
-  PCRE_ERROR_CALLOUT        (-9)
-
-This error is never generated by pcre_exec() itself. It is provided for -use by callout functions that want to yield a distinctive error code. See the -pcrecallout -documentation for details. -
-  PCRE_ERROR_BADUTF8        (-10)
-
-A string that contains an invalid UTF-8 byte sequence was passed as a subject. -
-  PCRE_ERROR_BADUTF8_OFFSET (-11)
-
-The UTF-8 byte sequence that was passed as a subject was valid, but the value -of startoffset did not point to the beginning of a UTF-8 character. -
-  PCRE_ERROR_PARTIAL (-12)
-
-The subject string did not match, but it did match partially. See the -pcrepartial -documentation for details of partial matching. -
-  PCRE_ERROR_BAD_PARTIAL (-13)
-
-The PCRE_PARTIAL option was used with a compiled pattern containing items that -are not supported for partial matching. See the -pcrepartial -documentation for details of partial matching. -
-  PCRE_ERROR_INTERNAL (-14)
-
-An unexpected internal error has occurred. This error could be caused by a bug -in PCRE or by overwriting of the compiled pattern. -
-  PCRE_ERROR_BADCOUNT (-15)
-
-This error is given if the value of the ovecsize argument is negative. -

-
EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
-

-int pcre_copy_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, char *buffer, -int buffersize); -

-

-int pcre_get_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, -const char **stringptr); -

-

-int pcre_get_substring_list(const char *subject, -int *ovector, int stringcount, const char ***listptr); -

-

-Captured substrings can be accessed directly by using the offsets returned by -pcre_exec() in ovector. For convenience, the functions -pcre_copy_substring(), pcre_get_substring(), and -pcre_get_substring_list() are provided for extracting captured substrings -as new, separate, zero-terminated strings. These functions identify substrings -by number. The next section describes functions for extracting named -substrings. A substring that contains a binary zero is correctly extracted and -has a further zero added on the end, but the result is not, of course, -a C string. -

-

-The first three arguments are the same for all three of these functions: -subject is the subject string that has just been successfully matched, -ovector is a pointer to the vector of integer offsets that was passed to -pcre_exec(), and stringcount is the number of substrings that were -captured by the match, including the substring that matched the entire regular -expression. This is the value returned by pcre_exec() if it is greater -than zero. If pcre_exec() returned zero, indicating that it ran out of -space in ovector, the value passed as stringcount should be the -number of elements in the vector divided by three. -

-

-The functions pcre_copy_substring() and pcre_get_substring() -extract a single substring, whose number is given as stringnumber. A -value of zero extracts the substring that matched the entire pattern, whereas -higher values extract the captured substrings. For pcre_copy_substring(), -the string is placed in buffer, whose length is given by -buffersize, while for pcre_get_substring() a new block of memory is -obtained via pcre_malloc, and its address is returned via -stringptr. The yield of the function is the length of the string, not -including the terminating zero, or one of -

-  PCRE_ERROR_NOMEMORY       (-6)
-
-The buffer was too small for pcre_copy_substring(), or the attempt to get -memory failed for pcre_get_substring(). -
-  PCRE_ERROR_NOSUBSTRING    (-7)
-
-There is no substring whose number is stringnumber. -

-

-The pcre_get_substring_list() function extracts all available substrings -and builds a list of pointers to them. All this is done in a single block of -memory that is obtained via pcre_malloc. The address of the memory block -is returned via listptr, which is also the start of the list of string -pointers. The end of the list is marked by a NULL pointer. The yield of the -function is zero if all went well, or -

-  PCRE_ERROR_NOMEMORY       (-6)
-
-if the attempt to get the memory block failed. -

-

-When any of these functions encounter a substring that is unset, which can -happen when capturing subpattern number n+1 matches some part of the -subject, but subpattern n has not been used at all, they return an empty -string. This can be distinguished from a genuine zero-length substring by -inspecting the appropriate offset in ovector, which is negative for unset -substrings. -

-

-The two convenience functions pcre_free_substring() and -pcre_free_substring_list() can be used to free the memory returned by -a previous call of pcre_get_substring() or -pcre_get_substring_list(), respectively. They do nothing more than call -the function pointed to by pcre_free, which of course could be called -directly from a C program. However, PCRE is used in some situations where it is -linked via a special interface to another programming language which cannot use -pcre_free directly; it is for these cases that the functions are -provided. -

-
EXTRACTING CAPTURED SUBSTRINGS BY NAME
-

-int pcre_get_stringnumber(const pcre *code, -const char *name); -

-

-int pcre_copy_named_substring(const pcre *code, -const char *subject, int *ovector, -int stringcount, const char *stringname, -char *buffer, int buffersize); -

-

-int pcre_get_named_substring(const pcre *code, -const char *subject, int *ovector, -int stringcount, const char *stringname, -const char **stringptr); -

-

-To extract a substring by name, you first have to find associated number. -For example, for this pattern -

-  (a+)b(?<xxx>\d+)...
-
-the number of the subpattern called "xxx" is 2. You can find the number from -the name by calling pcre_get_stringnumber(). The first argument is the -compiled pattern, and the second is the name. The yield of the function is the -subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of -that name. -

-

-Given the number, you can extract the substring directly, or use one of the -functions described in the previous section. For convenience, there are also -two functions that do the whole job. -

-

-Most of the arguments of pcre_copy_named_substring() and -pcre_get_named_substring() are the same as those for the similarly named -functions that extract by number. As these are described in the previous -section, they are not re-described here. There are just two differences: -

-

-First, instead of a substring number, a substring name is given. Second, there -is an extra argument, given at the start, which is a pointer to the compiled -pattern. This is needed in order to gain access to the name-to-number -translation table. -

-

-These functions call pcre_get_stringnumber(), and if it succeeds, they -then call pcre_copy_substring() or pcre_get_substring(), as -appropriate. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcrebuild.html b/srclib/pcre/doc/html/pcrebuild.html deleted file mode 100644 index 98c7d27e6e..0000000000 --- a/srclib/pcre/doc/html/pcrebuild.html +++ /dev/null @@ -1,186 +0,0 @@ - - -pcrebuild specification - - -

pcrebuild man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
PCRE BUILD-TIME OPTIONS
-

-This document describes the optional features of PCRE that can be selected when -the library is compiled. They are all selected, or deselected, by providing -options to the configure script that is run before the make -command. The complete list of options for configure (which includes the -standard ones such as the selection of the installation directory) can be -obtained by running -

-  ./configure --help
-
-The following sections describe certain options whose names begin with --enable -or --disable. These settings specify changes to the defaults for the -configure command. Because of the way that configure works, ---enable and --disable always come in pairs, so the complementary option always -exists as well, but as it specifies the default, it is not described. -

-
UTF-8 SUPPORT
-

-To build PCRE with support for UTF-8 character strings, add -

-  --enable-utf8
-
-to the configure command. Of itself, this does not make PCRE treat -strings as UTF-8. As well as compiling PCRE with this option, you also have -have to set the PCRE_UTF8 option when you call the pcre_compile() -function. -

-
UNICODE CHARACTER PROPERTY SUPPORT
-

-UTF-8 support allows PCRE to process character values greater than 255 in the -strings that it handles. On its own, however, it does not provide any -facilities for accessing the properties of such characters. If you want to be -able to use the pattern escapes \P, \p, and \X, which refer to Unicode -character properties, you must add -

-  --enable-unicode-properties
-
-to the configure command. This implies UTF-8 support, even if you have -not explicitly requested it. -

-

-Including Unicode property support adds around 90K of tables to the PCRE -library, approximately doubling its size. Only the general category properties -such as Lu and Nd are supported. Details are given in the -pcrepattern -documentation. -

-
CODE VALUE OF NEWLINE
-

-By default, PCRE treats character 10 (linefeed) as the newline character. This -is the normal newline character on Unix-like systems. You can compile PCRE to -use character 13 (carriage return) instead by adding -

-  --enable-newline-is-cr
-
-to the configure command. For completeness there is also a ---enable-newline-is-lf option, which explicitly specifies linefeed as the -newline character. -

-
BUILDING SHARED AND STATIC LIBRARIES
-

-The PCRE building process uses libtool to build both shared and static -Unix libraries by default. You can suppress one of these by adding one of -

-  --disable-shared
-  --disable-static
-
-to the configure command, as required. -

-
POSIX MALLOC USAGE
-

-When PCRE is called through the POSIX interface (see the -pcreposix -documentation), additional working storage is required for holding the pointers -to capturing substrings, because PCRE requires three integers per substring, -whereas the POSIX interface provides only two. If the number of expected -substrings is small, the wrapper function uses space on the stack, because this -is faster than using malloc() for each call. The default threshold above -which the stack is no longer used is 10; it can be changed by adding a setting -such as -

-  --with-posix-malloc-threshold=20
-
-to the configure command. -

-
LIMITING PCRE RESOURCE USAGE
-

-Internally, PCRE has a function called match(), which it calls repeatedly -(possibly recursively) when matching a pattern. By controlling the maximum -number of times this function may be called during a single matching operation, -a limit can be placed on the resources used by a single call to -pcre_exec(). The limit can be changed at run time, as described in the -pcreapi -documentation. The default is 10 million, but this can be changed by adding a -setting such as -

-  --with-match-limit=500000
-
-to the configure command. -

-
HANDLING VERY LARGE PATTERNS
-

-Within a compiled pattern, offset values are used to point from one part to -another (for example, from an opening parenthesis to an alternation -metacharacter). By default, two-byte values are used for these offsets, leading -to a maximum size for a compiled pattern of around 64K. This is sufficient to -handle all but the most gigantic patterns. Nevertheless, some people do want to -process enormous patterns, so it is possible to compile PCRE to use three-byte -or four-byte offsets by adding a setting such as -

-  --with-link-size=3
-
-to the configure command. The value given must be 2, 3, or 4. Using -longer offsets slows down the operation of PCRE because it has to load -additional bytes when handling them. -

-

-If you build PCRE with an increased link size, test 2 (and test 5 if you are -using UTF-8) will fail. Part of the output of these tests is a representation -of the compiled pattern, and this changes with the link size. -

-
AVOIDING EXCESSIVE STACK USAGE
-

-PCRE implements backtracking while matching by making recursive calls to an -internal function called match(). In environments where the size of the -stack is limited, this can severely limit PCRE's operation. (The Unix -environment does not usually suffer from this problem.) An alternative approach -that uses memory from the heap to remember data, instead of using recursive -function calls, has been implemented to work round this problem. If you want to -build a version of PCRE that works this way, add -

-  --disable-stack-for-recursion
-
-to the configure command. With this configuration, PCRE will use the -pcre_stack_malloc and pcre_stack_free variables to call memory -management functions. Separate functions are provided because the usage is very -predictable: the block sizes requested are always the same, and the blocks are -always freed in reverse order. A calling program might be able to implement -optimized functions that perform better than the standard malloc() and -free() functions. PCRE runs noticeably more slowly when built in this -way. -

-
USING EBCDIC CODE
-

-PCRE assumes by default that it will run in an environment where the character -code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be -compiled to run in an EBCDIC environment by adding -

-  --enable-ebcdic
-
-to the configure command. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcrecallout.html b/srclib/pcre/doc/html/pcrecallout.html deleted file mode 100644 index dc2ef51697..0000000000 --- a/srclib/pcre/doc/html/pcrecallout.html +++ /dev/null @@ -1,180 +0,0 @@ - - -pcrecallout specification - - -

pcrecallout man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
PCRE CALLOUTS
-

-int (*pcre_callout)(pcre_callout_block *); -

-

-PCRE provides a feature called "callout", which is a means of temporarily -passing control to the caller of PCRE in the middle of pattern matching. The -caller of PCRE provides an external function by putting its entry point in the -global variable pcre_callout. By default, this variable contains NULL, -which disables all calling out. -

-

-Within a regular expression, (?C) indicates the points at which the external -function is to be called. Different callout points can be identified by putting -a number less than 256 after the letter C. The default value is zero. -For example, this pattern has two callout points: -

-  (?C1)\deabc(?C2)def
-
-If the PCRE_AUTO_CALLOUT option bit is set when pcre_compile() is called, -PCRE automatically inserts callouts, all with number 255, before each item in -the pattern. For example, if PCRE_AUTO_CALLOUT is used with the pattern -
-  A(\d{2}|--)
-
-it is processed as if it were -
-
-(?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255) -
-
-Notice that there is a callout before and after each parenthesis and -alternation bar. Automatic callouts can be used for tracking the progress of -pattern matching. The -pcretest -command has an option that sets automatic callouts; when it is used, the output -indicates how the pattern is matched. This is useful information when you are -trying to optimize the performance of a particular pattern. -

-
MISSING CALLOUTS
-

-You should be aware that, because of optimizations in the way PCRE matches -patterns, callouts sometimes do not happen. For example, if the pattern is -

-  ab(?C4)cd
-
-PCRE knows that any matching string must contain the letter "d". If the subject -string is "abyz", the lack of "d" means that matching doesn't ever start, and -the callout is never reached. However, with "abyd", though the result is still -no match, the callout is obeyed. -

-
THE CALLOUT INTERFACE
-

-During matching, when PCRE reaches a callout point, the external function -defined by pcre_callout is called (if it is set). The only argument is a -pointer to a pcre_callout block. This structure contains the following -fields: -

-  int          version;
-  int          callout_number;
-  int         *offset_vector;
-  const char  *subject;
-  int          subject_length;
-  int          start_match;
-  int          current_position;
-  int          capture_top;
-  int          capture_last;
-  void        *callout_data;
-  int          pattern_position;
-  int          next_item_length;
-
-The version field is an integer containing the version number of the -block format. The initial version was 0; the current version is 1. The version -number will change again in future if additional fields are added, but the -intention is never to remove any of the existing fields. -

-

-The callout_number field contains the number of the callout, as compiled -into the pattern (that is, the number after ?C for manual callouts, and 255 for -automatically generated callouts). -

-

-The offset_vector field is a pointer to the vector of offsets that was -passed by the caller to pcre_exec(). The contents can be inspected in -order to extract substrings that have been matched so far, in the same way as -for extracting substrings after a match has completed. -

-

-The subject and subject_length fields contain copies of the values -that were passed to pcre_exec(). -

-

-The start_match field contains the offset within the subject at which the -current match attempt started. If the pattern is not anchored, the callout -function may be called several times from the same point in the pattern for -different starting points in the subject. -

-

-The current_position field contains the offset within the subject of the -current match pointer. -

-

-The capture_top field contains one more than the number of the highest -numbered captured substring so far. If no substrings have been captured, -the value of capture_top is one. -

-

-The capture_last field contains the number of the most recently captured -substring. If no substrings have been captured, its value is -1. -

-

-The callout_data field contains a value that is passed to -pcre_exec() by the caller specifically so that it can be passed back in -callouts. It is passed in the pcre_callout field of the pcre_extra -data structure. If no such data was passed, the value of callout_data in -a pcre_callout block is NULL. There is a description of the -pcre_extra structure in the -pcreapi -documentation. -

-

-The pattern_position field is present from version 1 of the -pcre_callout structure. It contains the offset to the next item to be -matched in the pattern string. -

-

-The next_item_length field is present from version 1 of the -pcre_callout structure. It contains the length of the next item to be -matched in the pattern string. When the callout immediately precedes an -alternation bar, a closing parenthesis, or the end of the pattern, the length -is zero. When the callout precedes an opening parenthesis, the length is that -of the entire subpattern. -

-

-The pattern_position and next_item_length fields are intended to -help in distinguishing between different automatic callouts, which all have the -same callout number. However, they are set for all callouts. -

-
RETURN VALUES
-

-The external callout function returns an integer to PCRE. If the value is zero, -matching proceeds as normal. If the value is greater than zero, matching fails -at the current point, but backtracking to test other matching possibilities -goes ahead, just as if a lookahead assertion had failed. If the value is less -than zero, the match is abandoned, and pcre_exec() returns the negative -value. -

-

-Negative values should normally be chosen from the set of PCRE_ERROR_xxx -values. In particular, PCRE_ERROR_NOMATCH forces a standard "no match" failure. -The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions; -it will never be used by PCRE itself. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcrecompat.html b/srclib/pcre/doc/html/pcrecompat.html deleted file mode 100644 index 6529c0966a..0000000000 --- a/srclib/pcre/doc/html/pcrecompat.html +++ /dev/null @@ -1,150 +0,0 @@ - - -pcrecompat specification - - -

pcrecompat man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-DIFFERENCES BETWEEN PCRE AND PERL -
-

-This document describes the differences in the ways that PCRE and Perl handle -regular expressions. The differences described here are with respect to Perl -5.8. -

-

-1. PCRE does not have full UTF-8 support. Details of what it does have are -given in the -section on UTF-8 support -in the main -pcre -page. -

-

-2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits -them, but they do not mean what you might think. For example, (?!a){3} does -not assert that the next three characters are not "a". It just asserts that the -next character is not "a" three times. -

-

-3. Capturing subpatterns that occur inside negative lookahead assertions are -counted, but their entries in the offsets vector are never set. Perl sets its -numerical variables from any such patterns that are matched before the -assertion fails to match something (thereby succeeding), but only if the -negative lookahead assertion contains just one branch. -

-

-4. Though binary zero characters are supported in the subject string, they are -not allowed in a pattern string because it is passed as a normal C string, -terminated by zero. The escape sequence \0 can be used in the pattern to -represent a binary zero. -

-

-5. The following Perl escape sequences are not supported: \l, \u, \L, -\U, and \N. In fact these are implemented by Perl's general string-handling -and are not part of its pattern matching engine. If any of these are -encountered by PCRE, an error is generated. -

-

-6. The Perl escape sequences \p, \P, and \X are supported only if PCRE is -built with Unicode character property support. The properties that can be -tested with \p and \P are limited to the general category properties such as -Lu and Nd. -

-

-7. PCRE does support the \Q...\E escape for quoting substrings. Characters in -between are treated as literals. This is slightly different from Perl in that $ -and @ are also handled as literals inside the quotes. In Perl, they cause -variable interpolation (but of course PCRE does not have variables). Note the -following examples: -

-    Pattern            PCRE matches      Perl matches
-
-    \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
-    \Qabc\$xyz\E       abc\$xyz          abc\$xyz
-    \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
-
-The \Q...\E sequence is recognized both inside and outside character classes. -

-

-8. Fairly obviously, PCRE does not support the (?{code}) and (?p{code}) -constructions. However, there is support for recursive patterns using the -non-Perl items (?R), (?number), and (?P>name). Also, the PCRE "callout" feature -allows an external function to be called during pattern matching. See the -pcrecallout -documentation for details. -

-

-9. There are some differences that are concerned with the settings of captured -strings when part of a pattern is repeated. For example, matching "aba" against -the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b". -

-

-10. PCRE provides some extensions to the Perl regular expression facilities: -
-
-(a) Although lookbehind assertions must match fixed length strings, each -alternative branch of a lookbehind assertion can match a different length of -string. Perl requires them all to have the same length. -
-
-(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ -meta-character matches only at the very end of the string. -
-
-(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special -meaning is faulted. -
-
-(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is -inverted, that is, by default they are not greedy, but if followed by a -question mark they are. -
-
-(e) PCRE_ANCHORED can be used at matching time to force a pattern to be tried -only at the first matching position in the subject string. -
-
-(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAPTURE -options for pcre_exec() have no Perl equivalents. -
-
-(g) The (?R), (?number), and (?P>name) constructs allows for recursive pattern -matching (Perl can do this using the (?p{code}) construct, which PCRE cannot -support.) -
-
-(h) PCRE supports named capturing substrings, using the Python syntax. -
-
-(i) PCRE supports the possessive quantifier "++" syntax, taken from Sun's Java -package. -
-
-(j) The (R) condition, for testing recursion, is a PCRE extension. -
-
-(k) The callout facility is PCRE-specific. -
-
-(l) The partial matching facility is PCRE-specific. -
-
-(m) Patterns compiled by PCRE can be saved and re-used at a later time, even on -different hosts that have the other endianness. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcregrep.html b/srclib/pcre/doc/html/pcregrep.html deleted file mode 100644 index 922487d440..0000000000 --- a/srclib/pcre/doc/html/pcregrep.html +++ /dev/null @@ -1,158 +0,0 @@ - - -pcregrep specification - - -

pcregrep man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
SYNOPSIS
-

-pcregrep [-Vcfhilnrsuvx] [long options] [pattern] [file1 file2 ...] -

-
DESCRIPTION
-

-pcregrep searches files for character patterns, in the same way as other -grep commands do, but it uses the PCRE regular expression library to support -patterns that are compatible with the regular expressions of Perl 5. See -pcrepattern -for a full description of syntax and semantics of the regular expressions that -PCRE supports. -

-

-A pattern must be specified on the command line unless the -f option is -used (see below). -

-

-If no files are specified, pcregrep reads the standard input. By default, -each line that matches the pattern is copied to the standard output, and if -there is more than one file, the file name is printed before each line of -output. However, there are options that can change how pcregrep behaves. -

-

-Lines are limited to BUFSIZ characters. BUFSIZ is defined in <stdio.h>. -The newline character is removed from the end of each line before it is matched -against the pattern. -

-
OPTIONS
-

--V -Write the version number of the PCRE library being used to the standard error -stream. -

-

--c -Do not print individual lines; instead just print a count of the number of -lines that would otherwise have been printed. If several files are given, a -count is printed for each of them. -

-

--ffilename -Read a number of patterns from the file, one per line, and match all of them -against each line of input. A line is output if any of the patterns match it. -When -f is used, no pattern is taken from the command line; all arguments -are treated as file names. There is a maximum of 100 patterns. Trailing white -space is removed, and blank lines are ignored. An empty file contains no -patterns and therefore matches nothing. -

-

--h -Suppress printing of filenames when searching multiple files. -

-

--i -Ignore upper/lower case distinctions during comparisons. -

-

--l -Instead of printing lines from the files, just print the names of the files -containing lines that would have been printed. Each file name is printed -once, on a separate line. -

-

--n -Precede each line by its line number in the file. -

-

--r -If any file is a directory, recursively scan the files it contains. Without --r a directory is scanned as a normal file. -

-

--s -Work silently, that is, display nothing except error messages. -The exit status indicates whether any matches were found. -

-

--u -Operate in UTF-8 mode. This option is available only if PCRE has been compiled -with UTF-8 support. Both the pattern and each subject line must be valid -strings of UTF-8 characters. -

-

--v -Invert the sense of the match, so that lines which do not match the -pattern are now the ones that are found. -

-

--x -Force the pattern to be anchored (it must start matching at the beginning of -the line) and in addition, require it to match the entire line. This is -equivalent to having ^ and $ characters at the start and end of each -alternative branch in the regular expression. -

-
LONG OPTIONS
-

-Long forms of all the options are available, as in GNU grep. They are shown in -the following table: -

-  -c   --count
-  -h   --no-filename
-  -i   --ignore-case
-  -l   --files-with-matches
-  -n   --line-number
-  -r   --recursive
-  -s   --no-messages
-  -u   --utf-8
-  -V   --version
-  -v   --invert-match
-  -x   --line-regex
-  -x   --line-regexp
-
-In addition, --file=filename is equivalent to -ffilename, and ---help shows the list of options and then exits. -

-
DIAGNOSTICS
-

-Exit status is 0 if any matches were found, 1 if no matches were found, and 2 -for syntax errors or inacessible files (even if matches were found). -

-
AUTHOR
-

-Philip Hazel <ph10@cam.ac.uk> -
-University Computing Service -
-Cambridge CB2 3QG, England. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcrepartial.html b/srclib/pcre/doc/html/pcrepartial.html deleted file mode 100644 index c4dd88613b..0000000000 --- a/srclib/pcre/doc/html/pcrepartial.html +++ /dev/null @@ -1,111 +0,0 @@ - - -pcrepartial specification - - -

pcrepartial man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
PARTIAL MATCHING IN PCRE
-

-In normal use of PCRE, if the subject string that is passed to -pcre_exec() matches as far as it goes, but is too short to match the -entire pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances where -it might be helpful to distinguish this case from other cases in which there is -no match. -

-

-Consider, for example, an application where a human is required to type in data -for a field with specific formatting requirements. An example might be a date -in the form ddmmmyy, defined by this pattern: -

-  ^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$
-
-If the application sees the user's keystrokes one by one, and can check that -what has been typed so far is potentially valid, it is able to raise an error -as soon as a mistake is made, possibly beeping and not reflecting the -character that has been typed. This immediate feedback is likely to be a better -user interface than a check that is delayed until the entire string has been -entered. -

-

-PCRE supports the concept of partial matching by means of the PCRE_PARTIAL -option, which can be set when calling pcre_exec(). When this is done, the -return code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if at any -time during the matching process the entire subject string matched part of the -pattern. No captured data is set when this occurs. -

-

-Using PCRE_PARTIAL disables one of PCRE's optimizations. PCRE remembers the -last literal byte in a pattern, and abandons matching immediately if such a -byte is not present in the subject string. This optimization cannot be used -for a subject string that might match only partially. -

-
RESTRICTED PATTERNS FOR PCRE_PARTIAL
-

-Because of the way certain internal optimizations are implemented in PCRE, the -PCRE_PARTIAL option cannot be used with all patterns. Repeated single -characters such as -

-  a{2,4}
-
-and repeated single metasequences such as -
-  \d+
-
-are not permitted if the maximum number of occurrences is greater than one. -Optional items such as \d? (where the maximum is one) are permitted. -Quantifiers with any values are permitted after parentheses, so the invalid -examples above can be coded thus: -
-  (a){2,4}
-  (\d)+
-
-These constructions run more slowly, but for the kinds of application that are -envisaged for this facility, this is not felt to be a major restriction. -

-

-If PCRE_PARTIAL is set for a pattern that does not conform to the restrictions, -pcre_exec() returns the error code PCRE_ERROR_BADPARTIAL (-13). -

-
EXAMPLE OF PARTIAL MATCHING USING PCRETEST
-

-If the escape sequence \P is present in a pcretest data line, the -PCRE_PARTIAL flag is used for the match. Here is a run of pcretest that -uses the date example quoted above: -

-    re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
-  data> 25jun04\P
-   0: 25jun04
-   1: jun
-  data> 25dec3\P
-  Partial match
-  data> 3ju\P
-  Partial match
-  data> 3juj\P
-  No match
-  data> j\P
-  No match
-
-The first data string is matched completely, so pcretest shows the -matched substrings. The remaining four strings do not match the complete -pattern, but the first two are partial matches. -

-

-Last updated: 08 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcrepattern.html b/srclib/pcre/doc/html/pcrepattern.html deleted file mode 100644 index 1220eb7e02..0000000000 --- a/srclib/pcre/doc/html/pcrepattern.html +++ /dev/null @@ -1,1470 +0,0 @@ - - -pcrepattern specification - - -

pcrepattern man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
PCRE REGULAR EXPRESSION DETAILS
-

-The syntax and semantics of the regular expressions supported by PCRE are -described below. Regular expressions are also described in the Perl -documentation and in a number of books, some of which have copious examples. -Jeffrey Friedl's "Mastering Regular Expressions", published by O'Reilly, covers -regular expressions in great detail. This description of PCRE's regular -expressions is intended as reference material. -

-

-The original operation of PCRE was on strings of one-byte characters. However, -there is now also support for UTF-8 character strings. To use this, you must -build PCRE to include UTF-8 support, and then call pcre_compile() with -the PCRE_UTF8 option. How this affects pattern matching is mentioned in several -places below. There is also a summary of UTF-8 features in the -section on UTF-8 support -in the main -pcre -page. -

-

-A regular expression is a pattern that is matched against a subject string from -left to right. Most characters stand for themselves in a pattern, and match the -corresponding characters in the subject. As a trivial example, the pattern -

-  The quick brown fox
-
-matches a portion of a subject string that is identical to itself. The power of -regular expressions comes from the ability to include alternatives and -repetitions in the pattern. These are encoded in the pattern by the use of -metacharacters, which do not stand for themselves but instead are -interpreted in some special way. -

-

-There are two different sets of metacharacters: those that are recognized -anywhere in the pattern except within square brackets, and those that are -recognized in square brackets. Outside square brackets, the metacharacters are -as follows: -

-  \      general escape character with several uses
-  ^      assert start of string (or line, in multiline mode)
-  $      assert end of string (or line, in multiline mode)
-  .      match any character except newline (by default)
-  [      start character class definition
-  |      start of alternative branch
-  (      start subpattern
-  )      end subpattern
-  ?      extends the meaning of (
-         also 0 or 1 quantifier
-         also quantifier minimizer
-  *      0 or more quantifier
-  +      1 or more quantifier
-         also "possessive quantifier"
-  {      start min/max quantifier
-
-Part of a pattern that is in square brackets is called a "character class". In -a character class the only metacharacters are: -
-  \      general escape character
-  ^      negate the class, but only if the first character
-  -      indicates character range
-  [      POSIX character class (only if followed by POSIX syntax)
-  ]      terminates the character class
-
-The following sections describe the use of each of the metacharacters. -

-
BACKSLASH
-

-The backslash character has several uses. Firstly, if it is followed by a -non-alphanumeric character, it takes away any special meaning that character may -have. This use of backslash as an escape character applies both inside and -outside character classes. -

-

-For example, if you want to match a * character, you write \* in the pattern. -This escaping action applies whether or not the following character would -otherwise be interpreted as a metacharacter, so it is always safe to precede a -non-alphanumeric with backslash to specify that it stands for itself. In -particular, if you want to match a backslash, you write \\. -

-

-If a pattern is compiled with the PCRE_EXTENDED option, whitespace in the -pattern (other than in a character class) and characters between a # outside -a character class and the next newline character are ignored. An escaping -backslash can be used to include a whitespace or # character as part of the -pattern. -

-

-If you want to remove the special meaning from a sequence of characters, you -can do so by putting them between \Q and \E. This is different from Perl in -that $ and @ are handled as literals in \Q...\E sequences in PCRE, whereas in -Perl, $ and @ cause variable interpolation. Note the following examples: -

-  Pattern            PCRE matches   Perl matches
-
-  \Qabc$xyz\E        abc$xyz        abc followed by the contents of $xyz
-  \Qabc\$xyz\E       abc\$xyz       abc\$xyz
-  \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
-
-The \Q...\E sequence is recognized both inside and outside character classes. -

-
-Non-printing characters -
-

-A second use of backslash provides a way of encoding non-printing characters -in patterns in a visible manner. There is no restriction on the appearance of -non-printing characters, apart from the binary zero that terminates a pattern, -but when a pattern is being prepared by text editing, it is usually easier to -use one of the following escape sequences than the binary character it -represents: -

-  \a        alarm, that is, the BEL character (hex 07)
-  \cx       "control-x", where x is any character
-  \e        escape (hex 1B)
-  \f        formfeed (hex 0C)
-  \n        newline (hex 0A)
-  \r        carriage return (hex 0D)
-  \t        tab (hex 09)
-  \ddd      character with octal code ddd, or backreference
-  \xhh      character with hex code hh
-  \x{hhh..} character with hex code hhh... (UTF-8 mode only)
-
-The precise effect of \cx is as follows: if x is a lower case letter, it -is converted to upper case. Then bit 6 of the character (hex 40) is inverted. -Thus \cz becomes hex 1A, but \c{ becomes hex 3B, while \c; becomes hex -7B. -

-

-After \x, from zero to two hexadecimal digits are read (letters can be in -upper or lower case). In UTF-8 mode, any number of hexadecimal digits may -appear between \x{ and }, but the value of the character code must be less -than 2**31 (that is, the maximum hexadecimal value is 7FFFFFFF). If characters -other than hexadecimal digits appear between \x{ and }, or if there is no -terminating }, this form of escape is not recognized. Instead, the initial -\x will be interpreted as a basic hexadecimal escape, with no following -digits, giving a character whose value is zero. -

-

-Characters whose value is less than 256 can be defined by either of the two -syntaxes for \x when PCRE is in UTF-8 mode. There is no difference in the -way they are handled. For example, \xdc is exactly the same as \x{dc}. -

-

-After \0 up to two further octal digits are read. In both cases, if there -are fewer than two digits, just those that are present are used. Thus the -sequence \0\x\07 specifies two binary zeros followed by a BEL character -(code value 7). Make sure you supply two digits after the initial zero if the -pattern character that follows is itself an octal digit. -

-

-The handling of a backslash followed by a digit other than 0 is complicated. -Outside a character class, PCRE reads it and any following digits as a decimal -number. If the number is less than 10, or if there have been at least that many -previous capturing left parentheses in the expression, the entire sequence is -taken as a back reference. A description of how this works is given -later, -following the discussion of -parenthesized subpatterns. -

-

-Inside a character class, or if the decimal number is greater than 9 and there -have not been that many capturing subpatterns, PCRE re-reads up to three octal -digits following the backslash, and generates a single byte from the least -significant 8 bits of the value. Any subsequent digits stand for themselves. -For example: -

-  \040   is another way of writing a space
-  \40    is the same, provided there are fewer than 40 previous capturing subpatterns
-  \7     is always a back reference
-  \11    might be a back reference, or another way of writing a tab
-  \011   is always a tab
-  \0113  is a tab followed by the character "3"
-  \113   might be a back reference, otherwise the character with octal code 113
-  \377   might be a back reference, otherwise the byte consisting entirely of 1 bits
-  \81    is either a back reference, or a binary zero followed by the two characters "8" and "1"
-
-Note that octal values of 100 or greater must not be introduced by a leading -zero, because no more than three octal digits are ever read. -

-

-All the sequences that define a single byte value or a single UTF-8 character -(in UTF-8 mode) can be used both inside and outside character classes. In -addition, inside a character class, the sequence \b is interpreted as the -backspace character (hex 08), and the sequence \X is interpreted as the -character "X". Outside a character class, these sequences have different -meanings -(see below). -

-
-Generic character types -
-

-The third use of backslash is for specifying generic character types. The -following are always recognized: -

-  \d     any decimal digit
-  \D     any character that is not a decimal digit
-  \s     any whitespace character
-  \S     any character that is not a whitespace character
-  \w     any "word" character
-  \W     any "non-word" character
-
-Each pair of escape sequences partitions the complete set of characters into -two disjoint sets. Any given character matches one, and only one, of each pair. -

-

-These character type sequences can appear both inside and outside character -classes. They each match one character of the appropriate type. If the current -matching point is at the end of the subject string, all of them fail, since -there is no character to match. -

-

-For compatibility with Perl, \s does not match the VT character (code 11). -This makes it different from the the POSIX "space" class. The \s characters -are HT (9), LF (10), FF (12), CR (13), and space (32). -

-

-A "word" character is an underscore or any character less than 256 that is a -letter or digit. The definition of letters and digits is controlled by PCRE's -low-valued character tables, and may vary if locale-specific matching is taking -place (see -"Locale support" -in the -pcreapi -page). For example, in the "fr_FR" (French) locale, some character codes -greater than 128 are used for accented letters, and these are matched by \w. -

-

-In UTF-8 mode, characters with values greater than 128 never match \d, \s, or -\w, and always match \D, \S, and \W. This is true even when Unicode -character property support is available. -

-
-Unicode character properties -
-

-When PCRE is built with Unicode character property support, three additional -escape sequences to match generic character types are available when UTF-8 mode -is selected. They are: -

- \p{xx}   a character with the xx property
- \P{xx}   a character without the xx property
- \X       an extended Unicode sequence
-
-The property names represented by xx above are limited to the -Unicode general category properties. Each character has exactly one such -property, specified by a two-letter abbreviation. For compatibility with Perl, -negation can be specified by including a circumflex between the opening brace -and the property name. For example, \p{^Lu} is the same as \P{Lu}. -

-

-If only one letter is specified with \p or \P, it includes all the properties -that start with that letter. In this case, in the absence of negation, the -curly brackets in the escape sequence are optional; these two examples have -the same effect: -

-  \p{L}
-  \pL
-
-The following property codes are supported: -
-  C     Other
-  Cc    Control
-  Cf    Format
-  Cn    Unassigned
-  Co    Private use
-  Cs    Surrogate
-
-  L     Letter
-  Ll    Lower case letter
-  Lm    Modifier letter
-  Lo    Other letter
-  Lt    Title case letter
-  Lu    Upper case letter
-
-  M     Mark
-  Mc    Spacing mark
-  Me    Enclosing mark
-  Mn    Non-spacing mark
-
-  N     Number
-  Nd    Decimal number
-  Nl    Letter number
-  No    Other number
-
-  P     Punctuation
-  Pc    Connector punctuation
-  Pd    Dash punctuation
-  Pe    Close punctuation
-  Pf    Final punctuation
-  Pi    Initial punctuation
-  Po    Other punctuation
-  Ps    Open punctuation
-
-  S     Symbol
-  Sc    Currency symbol
-  Sk    Modifier symbol
-  Sm    Mathematical symbol
-  So    Other symbol
-
-  Z     Separator
-  Zl    Line separator
-  Zp    Paragraph separator
-  Zs    Space separator
-
-Extended properties such as "Greek" or "InMusicalSymbols" are not supported by -PCRE. -

-

-Specifying caseless matching does not affect these escape sequences. For -example, \p{Lu} always matches only upper case letters. -

-

-The \X escape matches any number of Unicode characters that form an extended -Unicode sequence. \X is equivalent to -

-  (?>\PM\pM*)
-
-That is, it matches a character without the "mark" property, followed by zero -or more characters with the "mark" property, and treats the sequence as an -atomic group -(see below). -Characters with the "mark" property are typically accents that affect the -preceding character. -

-

-Matching characters by Unicode property is not fast, because PCRE has to search -a structure that contains data for over fifteen thousand characters. That is -why the traditional escape sequences such as \d and \w do not use Unicode -properties in PCRE. -

-
-Simple assertions -
-

-The fourth use of backslash is for certain simple assertions. An assertion -specifies a condition that has to be met at a particular point in a match, -without consuming any characters from the subject string. The use of -subpatterns for more complicated assertions is described -below. -The backslashed -assertions are: -

-  \b     matches at a word boundary
-  \B     matches when not at a word boundary
-  \A     matches at start of subject
-  \Z     matches at end of subject or before newline at end
-  \z     matches at end of subject
-  \G     matches at first matching position in subject
-
-These assertions may not appear in character classes (but note that \b has a -different meaning, namely the backspace character, inside a character class). -

-

-A word boundary is a position in the subject string where the current character -and the previous character do not both match \w or \W (i.e. one matches -\w and the other matches \W), or the start or end of the string if the -first or last character matches \w, respectively. -

-

-The \A, \Z, and \z assertions differ from the traditional circumflex and -dollar (described in the next section) in that they only ever match at the very -start and end of the subject string, whatever options are set. Thus, they are -independent of multiline mode. These three assertions are not affected by the -PCRE_NOTBOL or PCRE_NOTEOL options, which affect only the behaviour of the -circumflex and dollar metacharacters. However, if the startoffset -argument of pcre_exec() is non-zero, indicating that matching is to start -at a point other than the beginning of the subject, \A can never match. The -difference between \Z and \z is that \Z matches before a newline that is the -last character of the string as well as at the end of the string, whereas \z -matches only at the end. -

-

-The \G assertion is true only when the current matching position is at the -start point of the match, as specified by the startoffset argument of -pcre_exec(). It differs from \A when the value of startoffset is -non-zero. By calling pcre_exec() multiple times with appropriate -arguments, you can mimic Perl's /g option, and it is in this kind of -implementation where \G can be useful. -

-

-Note, however, that PCRE's interpretation of \G, as the start of the current -match, is subtly different from Perl's, which defines it as the end of the -previous match. In Perl, these can be different when the previously matched -string was empty. Because PCRE does just one match at a time, it cannot -reproduce this behaviour. -

-

-If all the alternatives of a pattern begin with \G, the expression is anchored -to the starting match position, and the "anchored" flag is set in the compiled -regular expression. -

-
CIRCUMFLEX AND DOLLAR
-

-Outside a character class, in the default matching mode, the circumflex -character is an assertion that is true only if the current matching point is -at the start of the subject string. If the startoffset argument of -pcre_exec() is non-zero, circumflex can never match if the PCRE_MULTILINE -option is unset. Inside a character class, circumflex has an entirely different -meaning -(see below). -

-

-Circumflex need not be the first character of the pattern if a number of -alternatives are involved, but it should be the first thing in each alternative -in which it appears if the pattern is ever to match that branch. If all -possible alternatives start with a circumflex, that is, if the pattern is -constrained to match only at the start of the subject, it is said to be an -"anchored" pattern. (There are also other constructs that can cause a pattern -to be anchored.) -

-

-A dollar character is an assertion that is true only if the current matching -point is at the end of the subject string, or immediately before a newline -character that is the last character in the string (by default). Dollar need -not be the last character of the pattern if a number of alternatives are -involved, but it should be the last item in any branch in which it appears. -Dollar has no special meaning in a character class. -

-

-The meaning of dollar can be changed so that it matches only at the very end of -the string, by setting the PCRE_DOLLAR_ENDONLY option at compile time. This -does not affect the \Z assertion. -

-

-The meanings of the circumflex and dollar characters are changed if the -PCRE_MULTILINE option is set. When this is the case, they match immediately -after and immediately before an internal newline character, respectively, in -addition to matching at the start and end of the subject string. For example, -the pattern /^abc$/ matches the subject string "def\nabc" (where \n -represents a newline character) in multiline mode, but not otherwise. -Consequently, patterns that are anchored in single line mode because all -branches start with ^ are not anchored in multiline mode, and a match for -circumflex is possible when the startoffset argument of pcre_exec() -is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is -set. -

-

-Note that the sequences \A, \Z, and \z can be used to match the start and -end of the subject in both modes, and if all branches of a pattern start with -\A it is always anchored, whether PCRE_MULTILINE is set or not. -

-
FULL STOP (PERIOD, DOT)
-

-Outside a character class, a dot in the pattern matches any one character in -the subject, including a non-printing character, but not (by default) newline. -In UTF-8 mode, a dot matches any UTF-8 character, which might be more than one -byte long, except (by default) newline. If the PCRE_DOTALL option is set, -dots match newlines as well. The handling of dot is entirely independent of the -handling of circumflex and dollar, the only relationship being that they both -involve newline characters. Dot has no special meaning in a character class. -

-
MATCHING A SINGLE BYTE
-

-Outside a character class, the escape sequence \C matches any one byte, both -in and out of UTF-8 mode. Unlike a dot, it can match a newline. The feature is -provided in Perl in order to match individual bytes in UTF-8 mode. Because it -breaks up UTF-8 characters into individual bytes, what remains in the string -may be a malformed UTF-8 string. For this reason, the \C escape sequence is -best avoided. -

-

-PCRE does not allow \C to appear in lookbehind assertions -(described below), -because in UTF-8 mode this would make it impossible to calculate the length of -the lookbehind. -

-
SQUARE BRACKETS AND CHARACTER CLASSES
-

-An opening square bracket introduces a character class, terminated by a closing -square bracket. A closing square bracket on its own is not special. If a -closing square bracket is required as a member of the class, it should be the -first data character in the class (after an initial circumflex, if present) or -escaped with a backslash. -

-

-A character class matches a single character in the subject. In UTF-8 mode, the -character may occupy more than one byte. A matched character must be in the set -of characters defined by the class, unless the first character in the class -definition is a circumflex, in which case the subject character must not be in -the set defined by the class. If a circumflex is actually required as a member -of the class, ensure it is not the first character, or escape it with a -backslash. -

-

-For example, the character class [aeiou] matches any lower case vowel, while -[^aeiou] matches any character that is not a lower case vowel. Note that a -circumflex is just a convenient notation for specifying the characters that -are in the class by enumerating those that are not. A class that starts with a -circumflex is not an assertion: it still consumes a character from the subject -string, and therefore it fails if the current pointer is at the end of the -string. -

-

-In UTF-8 mode, characters with values greater than 255 can be included in a -class as a literal string of bytes, or by using the \x{ escaping mechanism. -

-

-When caseless matching is set, any letters in a class represent both their -upper case and lower case versions, so for example, a caseless [aeiou] matches -"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a -caseful version would. When running in UTF-8 mode, PCRE supports the concept of -case for characters with values greater than 128 only when it is compiled with -Unicode property support. -

-

-The newline character is never treated in any special way in character classes, -whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE options is. A class -such as [^a] will always match a newline. -

-

-The minus (hyphen) character can be used to specify a range of characters in a -character class. For example, [d-m] matches any letter between d and m, -inclusive. If a minus character is required in a class, it must be escaped with -a backslash or appear in a position where it cannot be interpreted as -indicating a range, typically as the first or last character in the class. -

-

-It is not possible to have the literal character "]" as the end character of a -range. A pattern such as [W-]46] is interpreted as a class of two characters -("W" and "-") followed by a literal string "46]", so it would match "W46]" or -"-46]". However, if the "]" is escaped with a backslash it is interpreted as -the end of range, so [W-\]46] is interpreted as a class containing a range -followed by two other characters. The octal or hexadecimal representation of -"]" can also be used to end a range. -

-

-Ranges operate in the collating sequence of character values. They can also be -used for characters specified numerically, for example [\000-\037]. In UTF-8 -mode, ranges can include characters whose values are greater than 255, for -example [\x{100}-\x{2ff}]. -

-

-If a range that includes letters is used when caseless matching is set, it -matches the letters in either case. For example, [W-c] is equivalent to -[][\\^_`wxyzabc], matched caselessly, and in non-UTF-8 mode, if character -tables for the "fr_FR" locale are in use, [\xc8-\xcb] matches accented E -characters in both cases. In UTF-8 mode, PCRE supports the concept of case for -characters with values greater than 128 only when it is compiled with Unicode -property support. -

-

-The character types \d, \D, \p, \P, \s, \S, \w, and \W may also appear -in a character class, and add the characters that they match to the class. For -example, [\dABCDEF] matches any hexadecimal digit. A circumflex can -conveniently be used with the upper case character types to specify a more -restricted set of characters than the matching lower case type. For example, -the class [^\W_] matches any letter or digit, but not underscore. -

-

-The only metacharacters that are recognized in character classes are backslash, -hyphen (only where it can be interpreted as specifying a range), circumflex -(only at the start), opening square bracket (only when it can be interpreted as -introducing a POSIX class name - see the next section), and the terminating -closing square bracket. However, escaping other non-alphanumeric characters -does no harm. -

-
POSIX CHARACTER CLASSES
-

-Perl supports the POSIX notation for character classes. This uses names -enclosed by [: and :] within the enclosing square brackets. PCRE also supports -this notation. For example, -

-  [01[:alpha:]%]
-
-matches "0", "1", any alphabetic character, or "%". The supported class names -are -
-  alnum    letters and digits
-  alpha    letters
-  ascii    character codes 0 - 127
-  blank    space or tab only
-  cntrl    control characters
-  digit    decimal digits (same as \d)
-  graph    printing characters, excluding space
-  lower    lower case letters
-  print    printing characters, including space
-  punct    printing characters, excluding letters and digits
-  space    white space (not quite the same as \s)
-  upper    upper case letters
-  word     "word" characters (same as \w)
-  xdigit   hexadecimal digits
-
-The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), and -space (32). Notice that this list includes the VT character (code 11). This -makes "space" different to \s, which does not include VT (for Perl -compatibility). -

-

-The name "word" is a Perl extension, and "blank" is a GNU extension from Perl -5.8. Another Perl extension is negation, which is indicated by a ^ character -after the colon. For example, -

-  [12[:^digit:]]
-
-matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the POSIX -syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not -supported, and an error is given if they are encountered. -

-

-In UTF-8 mode, characters with values greater than 128 do not match any of -the POSIX character classes. -

-
VERTICAL BAR
-

-Vertical bar characters are used to separate alternative patterns. For example, -the pattern -

-  gilbert|sullivan
-
-matches either "gilbert" or "sullivan". Any number of alternatives may appear, -and an empty alternative is permitted (matching the empty string). -The matching process tries each alternative in turn, from left to right, -and the first one that succeeds is used. If the alternatives are within a -subpattern -(defined below), -"succeeds" means matching the rest of the main pattern as well as the -alternative in the subpattern. -

-
INTERNAL OPTION SETTING
-

-The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and -PCRE_EXTENDED options can be changed from within the pattern by a sequence of -Perl option letters enclosed between "(?" and ")". The option letters are -

-  i  for PCRE_CASELESS
-  m  for PCRE_MULTILINE
-  s  for PCRE_DOTALL
-  x  for PCRE_EXTENDED
-
-For example, (?im) sets caseless, multiline matching. It is also possible to -unset these options by preceding the letter with a hyphen, and a combined -setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and -PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also -permitted. If a letter appears both before and after the hyphen, the option is -unset. -

-

-When an option change occurs at top level (that is, not inside subpattern -parentheses), the change applies to the remainder of the pattern that follows. -If the change is placed right at the start of a pattern, PCRE extracts it into -the global options (and it will therefore show up in data extracted by the -pcre_fullinfo() function). -

-

-An option change within a subpattern affects only that part of the current -pattern that follows it, so -

-  (a(?i)b)c
-
-matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used). -By this means, options can be made to have different settings in different -parts of the pattern. Any changes made in one alternative do carry on -into subsequent branches within the same subpattern. For example, -
-  (a(?i)b|c)
-
-matches "ab", "aB", "c", and "C", even though when matching "C" the first -branch is abandoned before the option setting. This is because the effects of -option settings happen at compile time. There would be some very weird -behaviour otherwise. -

-

-The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed in the -same way as the Perl-compatible options by using the characters U and X -respectively. The (?X) flag setting is special in that it must always occur -earlier in the pattern than any of the additional features it turns on, even -when it is at top level. It is best to put it at the start. -

-
SUBPATTERNS
-

-Subpatterns are delimited by parentheses (round brackets), which can be nested. -Turning part of a pattern into a subpattern does two things: -
-
-1. It localizes a set of alternatives. For example, the pattern -

-  cat(aract|erpillar|)
-
-matches one of the words "cat", "cataract", or "caterpillar". Without the -parentheses, it would match "cataract", "erpillar" or the empty string. -
-
-2. It sets up the subpattern as a capturing subpattern. This means that, when -the whole pattern matches, that portion of the subject string that matched the -subpattern is passed back to the caller via the ovector argument of -pcre_exec(). Opening parentheses are counted from left to right (starting -from 1) to obtain numbers for the capturing subpatterns. -

-

-For example, if the string "the red king" is matched against the pattern -

-  the ((red|white) (king|queen))
-
-the captured substrings are "red king", "red", and "king", and are numbered 1, -2, and 3, respectively. -

-

-The fact that plain parentheses fulfil two functions is not always helpful. -There are often times when a grouping subpattern is required without a -capturing requirement. If an opening parenthesis is followed by a question mark -and a colon, the subpattern does not do any capturing, and is not counted when -computing the number of any subsequent capturing subpatterns. For example, if -the string "the white queen" is matched against the pattern -

-  the ((?:red|white) (king|queen))
-
-the captured substrings are "white queen" and "queen", and are numbered 1 and -2. The maximum number of capturing subpatterns is 65535, and the maximum depth -of nesting of all subpatterns, both capturing and non-capturing, is 200. -

-

-As a convenient shorthand, if any option settings are required at the start of -a non-capturing subpattern, the option letters may appear between the "?" and -the ":". Thus the two patterns -

-  (?i:saturday|sunday)
-  (?:(?i)saturday|sunday)
-
-match exactly the same set of strings. Because alternative branches are tried -from left to right, and options are not reset until the end of the subpattern -is reached, an option setting in one branch does affect subsequent branches, so -the above patterns match "SUNDAY" as well as "Saturday". -

-
NAMED SUBPATTERNS
-

-Identifying capturing parentheses by number is simple, but it can be very hard -to keep track of the numbers in complicated regular expressions. Furthermore, -if an expression is modified, the numbers may change. To help with this -difficulty, PCRE supports the naming of subpatterns, something that Perl does -not provide. The Python syntax (?P<name>...) is used. Names consist of -alphanumeric characters and underscores, and must be unique within a pattern. -

-

-Named capturing parentheses are still allocated numbers as well as names. The -PCRE API provides function calls for extracting the name-to-number translation -table from a compiled pattern. There is also a convenience function for -extracting a captured substring by name. For further details see the -pcreapi -documentation. -

-
REPETITION
-

-Repetition is specified by quantifiers, which can follow any of the following -items: -

-  a literal data character
-  the . metacharacter
-  the \C escape sequence
-  the \X escape sequence (in UTF-8 mode with Unicode properties)
-  an escape such as \d that matches a single character
-  a character class
-  a back reference (see next section)
-  a parenthesized subpattern (unless it is an assertion)
-
-The general repetition quantifier specifies a minimum and maximum number of -permitted matches, by giving the two numbers in curly brackets (braces), -separated by a comma. The numbers must be less than 65536, and the first must -be less than or equal to the second. For example: -
-  z{2,4}
-
-matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special -character. If the second number is omitted, but the comma is present, there is -no upper limit; if the second number and the comma are both omitted, the -quantifier specifies an exact number of required matches. Thus -
-  [aeiou]{3,}
-
-matches at least 3 successive vowels, but may match many more, while -
-  \d{8}
-
-matches exactly 8 digits. An opening curly bracket that appears in a position -where a quantifier is not allowed, or one that does not match the syntax of a -quantifier, is taken as a literal character. For example, {,6} is not a -quantifier, but a literal string of four characters. -

-

-In UTF-8 mode, quantifiers apply to UTF-8 characters rather than to individual -bytes. Thus, for example, \x{100}{2} matches two UTF-8 characters, each of -which is represented by a two-byte sequence. Similarly, when Unicode property -support is available, \X{3} matches three Unicode extended sequences, each of -which may be several bytes long (and they may be of different lengths). -

-

-The quantifier {0} is permitted, causing the expression to behave as if the -previous item and the quantifier were not present. -

-

-For convenience (and historical compatibility) the three most common -quantifiers have single-character abbreviations: -

-  *    is equivalent to {0,}
-  +    is equivalent to {1,}
-  ?    is equivalent to {0,1}
-
-It is possible to construct infinite loops by following a subpattern that can -match no characters with a quantifier that has no upper limit, for example: -
-  (a?)*
-
-Earlier versions of Perl and PCRE used to give an error at compile time for -such patterns. However, because there are cases where this can be useful, such -patterns are now accepted, but if any repetition of the subpattern does in fact -match no characters, the loop is forcibly broken. -

-

-By default, the quantifiers are "greedy", that is, they match as much as -possible (up to the maximum number of permitted times), without causing the -rest of the pattern to fail. The classic example of where this gives problems -is in trying to match comments in C programs. These appear between /* and */ -and within the comment, individual * and / characters may appear. An attempt to -match C comments by applying the pattern -

-  /\*.*\*/
-
-to the string -
-  /* first comment */  not comment  /* second comment */
-
-fails, because it matches the entire string owing to the greediness of the .* -item. -

-

-However, if a quantifier is followed by a question mark, it ceases to be -greedy, and instead matches the minimum number of times possible, so the -pattern -

-  /\*.*?\*/
-
-does the right thing with the C comments. The meaning of the various -quantifiers is not otherwise changed, just the preferred number of matches. -Do not confuse this use of question mark with its use as a quantifier in its -own right. Because it has two uses, it can sometimes appear doubled, as in -
-  \d??\d
-
-which matches one digit by preference, but can match two if that is the only -way the rest of the pattern matches. -

-

-If the PCRE_UNGREEDY option is set (an option which is not available in Perl), -the quantifiers are not greedy by default, but individual ones can be made -greedy by following them with a question mark. In other words, it inverts the -default behaviour. -

-

-When a parenthesized subpattern is quantified with a minimum repeat count that -is greater than 1 or with a limited maximum, more memory is required for the -compiled pattern, in proportion to the size of the minimum or maximum. -

-

-If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent -to Perl's /s) is set, thus allowing the . to match newlines, the pattern is -implicitly anchored, because whatever follows will be tried against every -character position in the subject string, so there is no point in retrying the -overall match at any position after the first. PCRE normally treats such a -pattern as though it were preceded by \A. -

-

-In cases where it is known that the subject string contains no newlines, it is -worth setting PCRE_DOTALL in order to obtain this optimization, or -alternatively using ^ to indicate anchoring explicitly. -

-

-However, there is one situation where the optimization cannot be used. When .* -is inside capturing parentheses that are the subject of a backreference -elsewhere in the pattern, a match at the start may fail, and a later one -succeed. Consider, for example: -

-  (.*)abc\1
-
-If the subject is "xyz123abc123" the match point is the fourth character. For -this reason, such a pattern is not implicitly anchored. -

-

-When a capturing subpattern is repeated, the value captured is the substring -that matched the final iteration. For example, after -

-  (tweedle[dume]{3}\s*)+
-
-has matched "tweedledum tweedledee" the value of the captured substring is -"tweedledee". However, if there are nested capturing subpatterns, the -corresponding captured values may have been set in previous iterations. For -example, after -
-  /(a|(b))+/
-
-matches "aba" the value of the second captured substring is "b". -

-
ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
-

-With both maximizing and minimizing repetition, failure of what follows -normally causes the repeated item to be re-evaluated to see if a different -number of repeats allows the rest of the pattern to match. Sometimes it is -useful to prevent this, either to change the nature of the match, or to cause -it fail earlier than it otherwise might, when the author of the pattern knows -there is no point in carrying on. -

-

-Consider, for example, the pattern \d+foo when applied to the subject line -

-  123456bar
-
-After matching all 6 digits and then failing to match "foo", the normal -action of the matcher is to try again with only 5 digits matching the \d+ -item, and then with 4, and so on, before ultimately failing. "Atomic grouping" -(a term taken from Jeffrey Friedl's book) provides the means for specifying -that once a subpattern has matched, it is not to be re-evaluated in this way. -

-

-If we use atomic grouping for the previous example, the matcher would give up -immediately on failing to match "foo" the first time. The notation is a kind of -special parenthesis, starting with (?> as in this example: -

-  (?>\d+)foo
-
-This kind of parenthesis "locks up" the part of the pattern it contains once -it has matched, and a failure further into the pattern is prevented from -backtracking into it. Backtracking past it to previous items, however, works as -normal. -

-

-An alternative description is that a subpattern of this type matches the string -of characters that an identical standalone pattern would match, if anchored at -the current point in the subject string. -

-

-Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as -the above example can be thought of as a maximizing repeat that must swallow -everything it can. So, while both \d+ and \d+? are prepared to adjust the -number of digits they match in order to make the rest of the pattern match, -(?>\d+) can only match an entire sequence of digits. -

-

-Atomic groups in general can of course contain arbitrarily complicated -subpatterns, and can be nested. However, when the subpattern for an atomic -group is just a single repeated item, as in the example above, a simpler -notation, called a "possessive quantifier" can be used. This consists of an -additional + character following a quantifier. Using this notation, the -previous example can be rewritten as -

-  \d++foo
-
-Possessive quantifiers are always greedy; the setting of the PCRE_UNGREEDY -option is ignored. They are a convenient notation for the simpler forms of -atomic group. However, there is no difference in the meaning or processing of a -possessive quantifier and the equivalent atomic group. -

-

-The possessive quantifier syntax is an extension to the Perl syntax. It -originates in Sun's Java package. -

-

-When a pattern contains an unlimited repeat inside a subpattern that can itself -be repeated an unlimited number of times, the use of an atomic group is the -only way to avoid some failing matches taking a very long time indeed. The -pattern -

-  (\D+|<\d+>)*[!?]
-
-matches an unlimited number of substrings that either consist of non-digits, or -digits enclosed in <>, followed by either ! or ?. When it matches, it runs -quickly. However, if it is applied to -
-  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-
-it takes a long time before reporting failure. This is because the string can -be divided between the internal \D+ repeat and the external * repeat in a -large number of ways, and all have to be tried. (The example uses [!?] rather -than a single character at the end, because both PCRE and Perl have an -optimization that allows for fast failure when a single character is used. They -remember the last single character that is required for a match, and fail early -if it is not present in the string.) If the pattern is changed so that it uses -an atomic group, like this: -
-  ((?>\D+)|<\d+>)*[!?]
-
-sequences of non-digits cannot be broken, and failure happens quickly. -

-
BACK REFERENCES
-

-Outside a character class, a backslash followed by a digit greater than 0 (and -possibly further digits) is a back reference to a capturing subpattern earlier -(that is, to its left) in the pattern, provided there have been that many -previous capturing left parentheses. -

-

-However, if the decimal number following the backslash is less than 10, it is -always taken as a back reference, and causes an error only if there are not -that many capturing left parentheses in the entire pattern. In other words, the -parentheses that are referenced need not be to the left of the reference for -numbers less than 10. See the subsection entitled "Non-printing characters" -above -for further details of the handling of digits following a backslash. -

-

-A back reference matches whatever actually matched the capturing subpattern in -the current subject string, rather than anything matching the subpattern -itself (see -"Subpatterns as subroutines" -below for a way of doing that). So the pattern -

-  (sens|respons)e and \1ibility
-
-matches "sense and sensibility" and "response and responsibility", but not -"sense and responsibility". If caseful matching is in force at the time of the -back reference, the case of letters is relevant. For example, -
-  ((?i)rah)\s+\1
-
-matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original -capturing subpattern is matched caselessly. -

-

-Back references to named subpatterns use the Python syntax (?P=name). We could -rewrite the above example as follows: -

-  (?<p1>(?i)rah)\s+(?P=p1)
-
-There may be more than one back reference to the same subpattern. If a -subpattern has not actually been used in a particular match, any back -references to it always fail. For example, the pattern -
-  (a|(bc))\2
-
-always fails if it starts to match "a" rather than "bc". Because there may be -many capturing parentheses in a pattern, all digits following the backslash are -taken as part of a potential back reference number. If the pattern continues -with a digit character, some delimiter must be used to terminate the back -reference. If the PCRE_EXTENDED option is set, this can be whitespace. -Otherwise an empty comment (see -"Comments" -below) can be used. -

-

-A back reference that occurs inside the parentheses to which it refers fails -when the subpattern is first used, so, for example, (a\1) never matches. -However, such references can be useful inside repeated subpatterns. For -example, the pattern -

-  (a|b\1)+
-
-matches any number of "a"s and also "aba", "ababbaa" etc. At each iteration of -the subpattern, the back reference matches the character string corresponding -to the previous iteration. In order for this to work, the pattern must be such -that the first iteration does not need to match the back reference. This can be -done using alternation, as in the example above, or by a quantifier with a -minimum of zero. -

-
ASSERTIONS
-

-An assertion is a test on the characters following or preceding the current -matching point that does not actually consume any characters. The simple -assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are described -above. -

-

-More complicated assertions are coded as subpatterns. There are two kinds: -those that look ahead of the current position in the subject string, and those -that look behind it. An assertion subpattern is matched in the normal way, -except that it does not cause the current matching position to be changed. -

-

-Assertion subpatterns are not capturing subpatterns, and may not be repeated, -because it makes no sense to assert the same thing several times. If any kind -of assertion contains capturing subpatterns within it, these are counted for -the purposes of numbering the capturing subpatterns in the whole pattern. -However, substring capturing is carried out only for positive assertions, -because it does not make sense for negative assertions. -

-
-Lookahead assertions -
-

-Lookahead assertions start -with (?= for positive assertions and (?! for negative assertions. For example, -

-  \w+(?=;)
-
-matches a word followed by a semicolon, but does not include the semicolon in -the match, and -
-  foo(?!bar)
-
-matches any occurrence of "foo" that is not followed by "bar". Note that the -apparently similar pattern -
-  (?!foo)bar
-
-does not find an occurrence of "bar" that is preceded by something other than -"foo"; it finds any occurrence of "bar" whatsoever, because the assertion -(?!foo) is always true when the next three characters are "bar". A -lookbehind assertion is needed to achieve the other effect. -

-

-If you want to force a matching failure at some point in a pattern, the most -convenient way to do it is with (?!) because an empty string always matches, so -an assertion that requires there not to be an empty string must always fail. -

-
-Lookbehind assertions -
-

-Lookbehind assertions start with (?<= for positive assertions and (?<! for -negative assertions. For example, -

-  (?<!foo)bar
-
-does find an occurrence of "bar" that is not preceded by "foo". The contents of -a lookbehind assertion are restricted such that all the strings it matches must -have a fixed length. However, if there are several alternatives, they do not -all have to have the same fixed length. Thus -
-  (?<=bullock|donkey)
-
-is permitted, but -
-  (?<!dogs?|cats?)
-
-causes an error at compile time. Branches that match different length strings -are permitted only at the top level of a lookbehind assertion. This is an -extension compared with Perl (at least for 5.8), which requires all branches to -match the same length of string. An assertion such as -
-  (?<=ab(c|de))
-
-is not permitted, because its single top-level branch can match two different -lengths, but it is acceptable if rewritten to use two top-level branches: -
-  (?<=abc|abde)
-
-The implementation of lookbehind assertions is, for each alternative, to -temporarily move the current position back by the fixed width and then try to -match. If there are insufficient characters before the current position, the -match is deemed to fail. -

-

-PCRE does not allow the \C escape (which matches a single byte in UTF-8 mode) -to appear in lookbehind assertions, because it makes it impossible to calculate -the length of the lookbehind. The \X escape, which can match different numbers -of bytes, is also not permitted. -

-

-Atomic groups can be used in conjunction with lookbehind assertions to specify -efficient matching at the end of the subject string. Consider a simple pattern -such as -

-  abcd$
-
-when applied to a long string that does not match. Because matching proceeds -from left to right, PCRE will look for each "a" in the subject and then see if -what follows matches the rest of the pattern. If the pattern is specified as -
-  ^.*abcd$
-
-the initial .* matches the entire string at first, but when this fails (because -there is no following "a"), it backtracks to match all but the last character, -then all but the last two characters, and so on. Once again the search for "a" -covers the entire string, from right to left, so we are no better off. However, -if the pattern is written as -
-  ^(?>.*)(?<=abcd)
-
-or, equivalently, using the possessive quantifier syntax, -
-  ^.*+(?<=abcd)
-
-there can be no backtracking for the .* item; it can match only the entire -string. The subsequent lookbehind assertion does a single test on the last four -characters. If it fails, the match fails immediately. For long strings, this -approach makes a significant difference to the processing time. -

-
-Using multiple assertions -
-

-Several assertions (of any sort) may occur in succession. For example, -

-  (?<=\d{3})(?<!999)foo
-
-matches "foo" preceded by three digits that are not "999". Notice that each of -the assertions is applied independently at the same point in the subject -string. First there is a check that the previous three characters are all -digits, and then there is a check that the same three characters are not "999". -This pattern does not match "foo" preceded by six characters, the first -of which are digits and the last three of which are not "999". For example, it -doesn't match "123abcfoo". A pattern to do that is -
-  (?<=\d{3}...)(?<!999)foo
-
-This time the first assertion looks at the preceding six characters, checking -that the first three are digits, and then the second assertion checks that the -preceding three characters are not "999". -

-

-Assertions can be nested in any combination. For example, -

-  (?<=(?<!foo)bar)baz
-
-matches an occurrence of "baz" that is preceded by "bar" which in turn is not -preceded by "foo", while -
-  (?<=\d{3}(?!999)...)foo
-
-is another pattern that matches "foo" preceded by three digits and any three -characters that are not "999". -

-
CONDITIONAL SUBPATTERNS
-

-It is possible to cause the matching process to obey a subpattern -conditionally or to choose between two alternative subpatterns, depending on -the result of an assertion, or whether a previous capturing subpattern matched -or not. The two possible forms of conditional subpattern are -

-  (?(condition)yes-pattern)
-  (?(condition)yes-pattern|no-pattern)
-
-If the condition is satisfied, the yes-pattern is used; otherwise the -no-pattern (if present) is used. If there are more than two alternatives in the -subpattern, a compile-time error occurs. -

-

-There are three kinds of condition. If the text between the parentheses -consists of a sequence of digits, the condition is satisfied if the capturing -subpattern of that number has previously matched. The number must be greater -than zero. Consider the following pattern, which contains non-significant white -space to make it more readable (assume the PCRE_EXTENDED option) and to divide -it into three parts for ease of discussion: -

-  ( \( )?    [^()]+    (?(1) \) )
-
-The first part matches an optional opening parenthesis, and if that -character is present, sets it as the first captured substring. The second part -matches one or more characters that are not parentheses. The third part is a -conditional subpattern that tests whether the first set of parentheses matched -or not. If they did, that is, if subject started with an opening parenthesis, -the condition is true, and so the yes-pattern is executed and a closing -parenthesis is required. Otherwise, since no-pattern is not present, the -subpattern matches nothing. In other words, this pattern matches a sequence of -non-parentheses, optionally enclosed in parentheses. -

-

-If the condition is the string (R), it is satisfied if a recursive call to the -pattern or subpattern has been made. At "top level", the condition is false. -This is a PCRE extension. Recursive patterns are described in the next section. -

-

-If the condition is not a sequence of digits or (R), it must be an assertion. -This may be a positive or negative lookahead or lookbehind assertion. Consider -this pattern, again containing non-significant white space, and with the two -alternatives on the second line: -

-  (?(?=[^a-z]*[a-z])
-  \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
-
-The condition is a positive lookahead assertion that matches an optional -sequence of non-letters followed by a letter. In other words, it tests for the -presence of at least one letter in the subject. If a letter is found, the -subject is matched against the first alternative; otherwise it is matched -against the second. This pattern matches strings in one of the two forms -dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits. -

-
COMMENTS
-

-The sequence (?# marks the start of a comment that continues up to the next -closing parenthesis. Nested parentheses are not permitted. The characters -that make up a comment play no part in the pattern matching at all. -

-

-If the PCRE_EXTENDED option is set, an unescaped # character outside a -character class introduces a comment that continues up to the next newline -character in the pattern. -

-
RECURSIVE PATTERNS
-

-Consider the problem of matching a string in parentheses, allowing for -unlimited nested parentheses. Without the use of recursion, the best that can -be done is to use a pattern that matches up to some fixed depth of nesting. It -is not possible to handle an arbitrary nesting depth. Perl provides a facility -that allows regular expressions to recurse (amongst other things). It does this -by interpolating Perl code in the expression at run time, and the code can -refer to the expression itself. A Perl pattern to solve the parentheses problem -can be created like this: -

-  $re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
-
-The (?p{...}) item interpolates Perl code at run time, and in this case refers -recursively to the pattern in which it appears. Obviously, PCRE cannot support -the interpolation of Perl code. Instead, it supports some special syntax for -recursion of the entire pattern, and also for individual subpattern recursion. -

-

-The special item that consists of (? followed by a number greater than zero and -a closing parenthesis is a recursive call of the subpattern of the given -number, provided that it occurs inside that subpattern. (If not, it is a -"subroutine" call, which is described in the next section.) The special item -(?R) is a recursive call of the entire regular expression. -

-

-For example, this PCRE pattern solves the nested parentheses problem (assume -the PCRE_EXTENDED option is set so that white space is ignored): -

-  \( ( (?>[^()]+) | (?R) )* \)
-
-First it matches an opening parenthesis. Then it matches any number of -substrings which can either be a sequence of non-parentheses, or a recursive -match of the pattern itself (that is a correctly parenthesized substring). -Finally there is a closing parenthesis. -

-

-If this were part of a larger pattern, you would not want to recurse the entire -pattern, so instead you could use this: -

-  ( \( ( (?>[^()]+) | (?1) )* \) )
-
-We have put the pattern into parentheses, and caused the recursion to refer to -them instead of the whole pattern. In a larger pattern, keeping track of -parenthesis numbers can be tricky. It may be more convenient to use named -parentheses instead. For this, PCRE uses (?P>name), which is an extension to -the Python syntax that PCRE uses for named parentheses (Perl does not provide -named parentheses). We could rewrite the above example as follows: -
-  (?P<pn> \( ( (?>[^()]+) | (?P>pn) )* \) )
-
-This particular example pattern contains nested unlimited repeats, and so the -use of atomic grouping for matching strings of non-parentheses is important -when applying the pattern to strings that do not match. For example, when this -pattern is applied to -
-  (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
-
-it yields "no match" quickly. However, if atomic grouping is not used, -the match runs for a very long time indeed because there are so many different -ways the + and * repeats can carve up the subject, and all have to be tested -before failure can be reported. -

-

-At the end of a match, the values set for any capturing subpatterns are those -from the outermost level of the recursion at which the subpattern value is set. -If you want to obtain intermediate values, a callout function can be used (see -the next section and the -pcrecallout -documentation). If the pattern above is matched against -

-  (ab(cd)ef)
-
-the value for the capturing parentheses is "ef", which is the last value taken -on at the top level. If additional parentheses are added, giving -
-  \( ( ( (?>[^()]+) | (?R) )* ) \)
-     ^                        ^
-     ^                        ^
-
-the string they capture is "ab(cd)ef", the contents of the top level -parentheses. If there are more than 15 capturing parentheses in a pattern, PCRE -has to obtain extra memory to store data during a recursion, which it does by -using pcre_malloc, freeing it via pcre_free afterwards. If no -memory can be obtained, the match fails with the PCRE_ERROR_NOMEMORY error. -

-

-Do not confuse the (?R) item with the condition (R), which tests for recursion. -Consider this pattern, which matches text in angle brackets, allowing for -arbitrary nesting. Only digits are allowed in nested brackets (that is, when -recursing), whereas any characters are permitted at the outer level. -

-  < (?: (?(R) \d++  | [^<>]*+) | (?R)) * >
-
-In this pattern, (?(R) is the start of a conditional subpattern, with two -different alternatives for the recursive and non-recursive cases. The (?R) item -is the actual recursive call. -

-
SUBPATTERNS AS SUBROUTINES
-

-If the syntax for a recursive subpattern reference (either by number or by -name) is used outside the parentheses to which it refers, it operates like a -subroutine in a programming language. An earlier example pointed out that the -pattern -

-  (sens|respons)e and \1ibility
-
-matches "sense and sensibility" and "response and responsibility", but not -"sense and responsibility". If instead the pattern -
-  (sens|respons)e and (?1)ibility
-
-is used, it does match "sense and responsibility" as well as the other two -strings. Such references must, however, follow the subpattern to which they -refer. -

-
CALLOUTS
-

-Perl has a feature whereby using the sequence (?{...}) causes arbitrary Perl -code to be obeyed in the middle of matching a regular expression. This makes it -possible, amongst other things, to extract different substrings that match the -same pair of parentheses when there is a repetition. -

-

-PCRE provides a similar feature, but of course it cannot obey arbitrary Perl -code. The feature is called "callout". The caller of PCRE provides an external -function by putting its entry point in the global variable pcre_callout. -By default, this variable contains NULL, which disables all calling out. -

-

-Within a regular expression, (?C) indicates the points at which the external -function is to be called. If you want to identify different callout points, you -can put a number less than 256 after the letter C. The default value is zero. -For example, this pattern has two callout points: -

-  (?C1)\dabc(?C2)def
-
-If the PCRE_AUTO_CALLOUT flag is passed to pcre_compile(), callouts are -automatically installed before each item in the pattern. They are all numbered -255. -

-

-During matching, when PCRE reaches a callout point (and pcre_callout is -set), the external function is called. It is provided with the number of the -callout, the position in the pattern, and, optionally, one item of data -originally supplied by the caller of pcre_exec(). The callout function -may cause matching to proceed, to backtrack, or to fail altogether. A complete -description of the interface to the callout function is given in the -pcrecallout -documentation. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcreperform.html b/srclib/pcre/doc/html/pcreperform.html deleted file mode 100644 index f0ffa68188..0000000000 --- a/srclib/pcre/doc/html/pcreperform.html +++ /dev/null @@ -1,97 +0,0 @@ - - -pcreperform specification - - -

pcreperform man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-PCRE PERFORMANCE -
-

-Certain items that may appear in regular expression patterns are more efficient -than others. It is more efficient to use a character class like [aeiou] than a -set of alternatives such as (a|e|i|o|u). In general, the simplest construction -that provides the required behaviour is usually the most efficient. Jeffrey -Friedl's book contains a lot of useful general discussion about optimizing -regular expressions for efficient performance. This document contains a few -observations about PCRE. -

-

-Using Unicode character properties (the \p, \P, and \X escapes) is slow, -because PCRE has to scan a structure that contains data for over fifteen -thousand characters whenever it needs a character's property. If you can find -an alternative pattern that does not use character properties, it will probably -be faster. -

-

-When a pattern begins with .* not in parentheses, or in parentheses that are -not the subject of a backreference, and the PCRE_DOTALL option is set, the -pattern is implicitly anchored by PCRE, since it can match only at the start of -a subject string. However, if PCRE_DOTALL is not set, PCRE cannot make this -optimization, because the . metacharacter does not then match a newline, and if -the subject string contains newlines, the pattern may match from the character -immediately following one of them instead of from the very start. For example, -the pattern -

-  .*second
-
-matches the subject "first\nand second" (where \n stands for a newline -character), with the match starting at the seventh character. In order to do -this, PCRE has to retry the match starting after every newline in the subject. -

-

-If you are using such a pattern with subject strings that do not contain -newlines, the best performance is obtained by setting PCRE_DOTALL, or starting -the pattern with ^.* to indicate explicit anchoring. That saves PCRE from -having to scan along the subject looking for a newline to restart at. -

-

-Beware of patterns that contain nested indefinite repeats. These can take a -long time to run when applied to a string that does not match. Consider the -pattern fragment -

-  (a+)*
-
-This can match "aaaa" in 33 different ways, and this number increases very -rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4 -times, and for each of those cases other than 0, the + repeats can match -different numbers of times.) When the remainder of the pattern is such that the -entire match is going to fail, PCRE has in principle to try every possible -variation, and this can take an extremely long time. -

-

-An optimization catches some of the more simple cases such as -

-  (a+)*b
-
-where a literal character follows. Before embarking on the standard matching -procedure, PCRE checks that there is a "b" later in the subject string, and if -there is not, it fails the match immediately. However, when there is no -following literal this optimization cannot be used. You can see the difference -by comparing the behaviour of -
-  (a+)*\d
-
-with the pattern above. The former gives a failure almost instantly when -applied to a whole line of "a" characters, whereas the latter takes an -appreciable time with strings longer than about 20 characters. -

-

-In many cases, the solution to this kind of performance issue is to use an -atomic group or a possessive quantifier. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcreposix.html b/srclib/pcre/doc/html/pcreposix.html deleted file mode 100644 index 2f7aaa9d9c..0000000000 --- a/srclib/pcre/doc/html/pcreposix.html +++ /dev/null @@ -1,218 +0,0 @@ - - -pcreposix specification - - -

pcreposix man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
SYNOPSIS OF POSIX API
-

-#include <pcreposix.h> -

-

-int regcomp(regex_t *preg, const char *pattern, -int cflags); -

-

-int regexec(regex_t *preg, const char *string, -size_t nmatch, regmatch_t pmatch[], int eflags); -

-

-size_t regerror(int errcode, const regex_t *preg, -char *errbuf, size_t errbuf_size); -

-

-void regfree(regex_t *preg); -

-
DESCRIPTION
-

-This set of functions provides a POSIX-style API to the PCRE regular expression -package. See the -pcreapi -documentation for a description of PCRE's native API, which contains additional -functionality. -

-

-The functions described here are just wrapper functions that ultimately call -the PCRE native API. Their prototypes are defined in the pcreposix.h -header file, and on Unix systems the library itself is called -pcreposix.a, so can be accessed by adding -lpcreposix to the -command for linking an application that uses them. Because the POSIX functions -call the native ones, it is also necessary to add -lpcre. -

-

-I have implemented only those option bits that can be reasonably mapped to PCRE -native options. In addition, the options REG_EXTENDED and REG_NOSUB are defined -with the value zero. They have no effect, but since programs that are written -to the POSIX interface often use them, this makes it easier to slot in PCRE as -a replacement library. Other POSIX options are not even defined. -

-

-When PCRE is called via these functions, it is only the API that is POSIX-like -in style. The syntax and semantics of the regular expressions themselves are -still those of Perl, subject to the setting of various PCRE options, as -described below. "POSIX-like in style" means that the API approximates to the -POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding -domains it is probably even less compatible. -

-

-The header for these functions is supplied as pcreposix.h to avoid any -potential clash with other POSIX libraries. It can, of course, be renamed or -aliased as regex.h, which is the "correct" name. It provides two -structure types, regex_t for compiled internal forms, and -regmatch_t for returning captured substrings. It also defines some -constants whose names start with "REG_"; these are used for setting options and -identifying error codes. -

-

-

-
COMPILING A PATTERN
-

-The function regcomp() is called to compile a pattern into an -internal form. The pattern is a C string terminated by a binary zero, and -is passed in the argument pattern. The preg argument is a pointer -to a regex_t structure that is used as a base for storing information -about the compiled expression. -

-

-The argument cflags is either zero, or contains one or more of the bits -defined by the following macros: -

-  REG_ICASE
-
-The PCRE_CASELESS option is set when the expression is passed for compilation -to the native function. -
-  REG_NEWLINE
-
-The PCRE_MULTILINE option is set when the expression is passed for compilation -to the native function. Note that this does not mimic the defined POSIX -behaviour for REG_NEWLINE (see the following section). -

-

-In the absence of these flags, no options are passed to the native function. -This means the the regex is compiled with PCRE default semantics. In -particular, the way it handles newline characters in the subject string is the -Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only -some of the effects specified for REG_NEWLINE. It does not affect the way -newlines are matched by . (they aren't) or by a negative class such as [^a] -(they are). -

-

-The yield of regcomp() is zero on success, and non-zero otherwise. The -preg structure is filled in on success, and one member of the structure -is public: re_nsub contains the number of capturing subpatterns in -the regular expression. Various error codes are defined in the header file. -

-
MATCHING NEWLINE CHARACTERS
-

-This area is not simple, because POSIX and Perl take different views of things. -It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never -intended to be a POSIX engine. The following table lists the different -possibilities for matching newline characters in PCRE: -

-                          Default   Change with
-
-  . matches newline          no     PCRE_DOTALL
-  newline matches [^a]       yes    not changeable
-  $ matches \n at end        yes    PCRE_DOLLARENDONLY
-  $ matches \n in middle     no     PCRE_MULTILINE
-  ^ matches \n in middle     no     PCRE_MULTILINE
-
-This is the equivalent table for POSIX: -
-                          Default   Change with
-
-  . matches newline          yes    REG_NEWLINE
-  newline matches [^a]       yes    REG_NEWLINE
-  $ matches \n at end        no     REG_NEWLINE
-  $ matches \n in middle     no     REG_NEWLINE
-  ^ matches \n in middle     no     REG_NEWLINE
-
-PCRE's behaviour is the same as Perl's, except that there is no equivalent for -PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop -newline from matching [^a]. -

-

-The default POSIX newline handling can be obtained by setting PCRE_DOTALL and -PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the -REG_NEWLINE action. -

-
MATCHING A PATTERN
-

-The function regexec() is called to match a compiled pattern preg -against a given string, which is terminated by a zero byte, subject to -the options in eflags. These can be: -

-  REG_NOTBOL
-
-The PCRE_NOTBOL option is set when calling the underlying PCRE matching -function. -
-  REG_NOTEOL
-
-The PCRE_NOTEOL option is set when calling the underlying PCRE matching -function. -

-

-The portion of the string that was matched, and also any captured substrings, -are returned via the pmatch argument, which points to an array of -nmatch structures of type regmatch_t, containing the members -rm_so and rm_eo. These contain the offset to the first character of -each substring and the offset to the first character after the end of each -substring, respectively. The 0th element of the vector relates to the entire -portion of string that was matched; subsequent elements relate to the -capturing subpatterns of the regular expression. Unused entries in the array -have both structure members set to -1. -

-

-A successful match yields a zero return; various error codes are defined in the -header file, of which REG_NOMATCH is the "expected" failure code. -

-
ERROR MESSAGES
-

-The regerror() function maps a non-zero errorcode from either -regcomp() or regexec() to a printable message. If preg is not -NULL, the error should have arisen from the use of that structure. A message -terminated by a binary zero is placed in errbuf. The length of the -message, including the zero, is limited to errbuf_size. The yield of the -function is the size of buffer needed to hold the whole message. -

-
MEMORY USAGE
-

-Compiling a regular expression causes memory to be allocated and associated -with the preg structure. The function regfree() frees all such -memory, after which preg may no longer be used as a compiled expression. -

-
AUTHOR
-

-Philip Hazel <ph10@cam.ac.uk> -
-University Computing Service, -
-Cambridge CB2 3QG, England. -

-

-Last updated: 07 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcreprecompile.html b/srclib/pcre/doc/html/pcreprecompile.html deleted file mode 100644 index f1c109e7c3..0000000000 --- a/srclib/pcre/doc/html/pcreprecompile.html +++ /dev/null @@ -1,133 +0,0 @@ - - -pcreprecompile specification - - -

pcreprecompile man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
SAVING AND RE-USING PRECOMPILED PCRE PATTERNS
-

-If you are running an application that uses a large number of regular -expression patterns, it may be useful to store them in a precompiled form -instead of having to compile them every time the application is run. -If you are not using any private character tables (see the -pcre_maketables() -documentation), this is relatively straightforward. If you are using private -tables, it is a little bit more complicated. -

-

-If you save compiled patterns to a file, you can copy them to a different host -and run them there. This works even if the new host has the opposite endianness -to the one on which the patterns were compiled. There may be a small -performance penalty, but it should be insignificant. -

-
SAVING A COMPILED PATTERN
-

-The value returned by pcre_compile() points to a single block of memory -that holds the compiled pattern and associated data. You can find the length of -this block in bytes by calling pcre_fullinfo() with an argument of -PCRE_INFO_SIZE. You can then save the data in any appropriate manner. Here is -sample code that compiles a pattern and writes it to a file. It assumes that -the variable fd refers to a file that is open for output: -

-  int erroroffset, rc, size;
-  char *error;
-  pcre *re;
-
-  re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL);
-  if (re == NULL) { ... handle errors ... }
-  rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size);
-  if (rc < 0) { ... handle errors ... }
-  rc = fwrite(re, 1, size, fd);
-  if (rc != size) { ... handle errors ... }
-
-In this example, the bytes that comprise the compiled pattern are copied -exactly. Note that this is binary data that may contain any of the 256 possible -byte values. On systems that make a distinction between binary and non-binary -data, be sure that the file is opened for binary output. -

-

-If you want to write more than one pattern to a file, you will have to devise a -way of separating them. For binary data, preceding each pattern with its length -is probably the most straightforward approach. Another possibility is to write -out the data in hexadecimal instead of binary, one pattern to a line. -

-

-Saving compiled patterns in a file is only one possible way of storing them for -later use. They could equally well be saved in a database, or in the memory of -some daemon process that passes them via sockets to the processes that want -them. -

-

-If the pattern has been studied, it is also possible to save the study data in -a similar way to the compiled pattern itself. When studying generates -additional information, pcre_study() returns a pointer to a -pcre_extra data block. Its format is defined in the -section on matching a pattern -in the -pcreapi -documentation. The study_data field points to the binary study data, and -this is what you must save (not the pcre_extra block itself). The length -of the study data can be obtained by calling pcre_fullinfo() with an -argument of PCRE_INFO_STUDYSIZE. Remember to check that pcre_study() did -return a non-NULL value before trying to save the study data. -

-
RE-USING A PRECOMPILED PATTERN
-

-Re-using a precompiled pattern is straightforward. Having reloaded it into main -memory, you pass its pointer to pcre_exec() in the usual way. This should -work even on another host, and even if that host has the opposite endianness to -the one where the pattern was compiled. -

-

-However, if you passed a pointer to custom character tables when the pattern -was compiled (the tableptr argument of pcre_compile()), you must -now pass a similar pointer to pcre_exec(), because the value saved with -the compiled pattern will obviously be nonsense. A field in a -pcre_extra() block is used to pass this data, as described in the -section on matching a pattern -in the -pcreapi -documentation. -

-

-If you did not provide custom character tables when the pattern was compiled, -the pointer in the compiled pattern is NULL, which causes pcre_exec() to -use PCRE's internal tables. Thus, you do not need to take any special action at -run time in this case. -

-

-If you saved study data with the compiled pattern, you need to create your own -pcre_extra data block and set the study_data field to point to the -reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in the -flags field to indicate that study data is present. Then pass the -pcre_extra block to pcre_exec() in the usual way. -

-
COMPATIBILITY WITH DIFFERENT PCRE RELEASES
-

-The layout of the control block that is at the start of the data that makes up -a compiled pattern was changed for release 5.0. If you have any saved patterns -that were compiled with previous releases (not a facility that was previously -advertised), you will have to recompile them for release 5.0. However, from now -on, it should be possible to make changes in a compabible manner. -

-

-Last updated: 10 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcresample.html b/srclib/pcre/doc/html/pcresample.html deleted file mode 100644 index 91cd41137d..0000000000 --- a/srclib/pcre/doc/html/pcresample.html +++ /dev/null @@ -1,81 +0,0 @@ - - -pcresample specification - - -

pcresample man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-
-PCRE SAMPLE PROGRAM -
-

-A simple, complete demonstration program, to get you started with using PCRE, -is supplied in the file pcredemo.c in the PCRE distribution. -

-

-The program compiles the regular expression that is its first argument, and -matches it against the subject string in its second argument. No PCRE options -are set, and default character tables are used. If matching succeeds, the -program outputs the portion of the subject that matched, together with the -contents of any captured substrings. -

-

-If the -g option is given on the command line, the program then goes on to -check for further matches of the same regular expression in the same subject -string. The logic is a little bit tricky because of the possibility of matching -an empty string. Comments in the code explain what is going on. -

-

-If PCRE is installed in the standard include and library directories for your -system, you should be able to compile the demonstration program using this -command: -

-  gcc -o pcredemo pcredemo.c -lpcre
-
-If PCRE is installed elsewhere, you may need to add additional options to the -command line. For example, on a Unix-like system that has PCRE installed in -/usr/local, you can compile the demonstration program using a command -like this: -
-  gcc -o pcredemo -I/usr/local/include pcredemo.c -L/usr/local/lib -lpcre
-
-Once you have compiled the demonstration program, you can run simple tests like -this: -
-  ./pcredemo 'cat|dog' 'the cat sat on the mat'
-  ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
-
-Note that there is a much more comprehensive test program, called -pcretest, -which supports many more facilities for testing regular expressions and the -PCRE library. The pcredemo program is provided as a simple coding -example. -

-

-On some operating systems (e.g. Solaris), when PCRE is not installed in the -standard library directory, you may get an error like this when you try to run -pcredemo: -

-  ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
-
-This is caused by the way shared library support works on those systems. You -need to add -
-  -R/usr/local/lib
-
-(for example) to the compile command to get round this problem. -

-

-Last updated: 09 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/html/pcretest.html b/srclib/pcre/doc/html/pcretest.html deleted file mode 100644 index d82dfcc6a5..0000000000 --- a/srclib/pcre/doc/html/pcretest.html +++ /dev/null @@ -1,495 +0,0 @@ - - -pcretest specification - - -

pcretest man page

-

-Return to the PCRE index page. -

-

-This page is part of the PCRE HTML documentation. It was generated automatically -from the original man page. If there is any nonsense in it, please consult the -man page, in case the conversion went wrong. -
-

-
SYNOPSIS
-

-pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source] -[destination] -

-

-pcretest was written as a test program for the PCRE regular expression -library itself, but it can also be used for experimenting with regular -expressions. This document describes the features of the test program; for -details of the regular expressions themselves, see the -pcrepattern -documentation. For details of the PCRE library function calls and their -options, see the -pcreapi -documentation. -

-
OPTIONS
-

--C -Output the version number of the PCRE library, and all available information -about the optional features that are included, and then exit. -

-

--d -Behave as if each regex had the /D (debug) modifier; the internal -form is output after compilation. -

-

--i -Behave as if each regex had the /I modifier; information about the -compiled pattern is given after compilation. -

-

--m -Output the size of each compiled pattern after it has been compiled. This is -equivalent to adding /M to each regular expression. For compatibility -with earlier versions of pcretest, -s is a synonym for -m. -

-

--o osize -Set the number of elements in the output vector that is used when calling -pcre_exec() to be osize. The default value is 45, which is enough -for 14 capturing subexpressions. The vector size can be changed for individual -matching calls by including \O in the data line (see below). -

-

--p -Behave as if each regex has /P modifier; the POSIX wrapper API is used -to call PCRE. None of the other options has any effect when -p is set. -

-

--t -Run each compile, study, and match many times with a timer, and output -resulting time per compile or match (in milliseconds). Do not set -m with --t, because you will then get the size output a zillion times, and the -timing will be distorted. -

-
DESCRIPTION
-

-If pcretest is given two filename arguments, it reads from the first and -writes to the second. If it is given only one filename argument, it reads from -that file and writes to stdout. Otherwise, it reads from stdin and writes to -stdout, and prompts for each line of input, using "re>" to prompt for regular -expressions, and "data>" to prompt for data lines. -

-

-The program handles any number of sets of input on a single input file. Each -set starts with a regular expression, and continues with any number of data -lines to be matched against the pattern. -

-

-Each data line is matched separately and independently. If you want to do -multiple-line matches, you have to use the \n escape sequence in a single line -of input to encode the newline characters. The maximum length of data line is -30,000 characters. -

-

-An empty line signals the end of the data lines, at which point a new regular -expression is read. The regular expressions are given enclosed in any -non-alphanumeric delimiters other than backslash, for example -

-  /(a|bc)x+yz/
-
-White space before the initial delimiter is ignored. A regular expression may -be continued over several input lines, in which case the newline characters are -included within it. It is possible to include the delimiter within the pattern -by escaping it, for example -
-  /abc\/def/
-
-If you do so, the escape and the delimiter form part of the pattern, but since -delimiters are always non-alphanumeric, this does not affect its interpretation. -If the terminating delimiter is immediately followed by a backslash, for -example, -
-  /abc/\
-
-then a backslash is added to the end of the pattern. This is done to provide a -way of testing the error condition that arises if a pattern finishes with a -backslash, because -
-  /abc\/
-
-is interpreted as the first line of a pattern that starts with "abc/", causing -pcretest to read the next line as a continuation of the regular expression. -

-
PATTERN MODIFIERS
-

-A pattern may be followed by any number of modifiers, which are mostly single -characters. Following Perl usage, these are referred to below as, for example, -"the /i modifier", even though the delimiter of the pattern need not -always be a slash, and no slash is used when writing modifiers. Whitespace may -appear between the final pattern delimiter and the first modifier, and between -the modifiers themselves. -

-

-The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, -PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when -pcre_compile() is called. These four modifier letters have the same -effect as they do in Perl. For example: -

-  /caseless/i
-
-The following table shows additional modifiers for setting PCRE options that do -not correspond to anything in Perl: -
-  /A    PCRE_ANCHORED
-  /C    PCRE_AUTO_CALLOUT
-  /E    PCRE_DOLLAR_ENDONLY
-  /N    PCRE_NO_AUTO_CAPTURE
-  /U    PCRE_UNGREEDY
-  /X    PCRE_EXTRA
-
-Searching for all possible matches within each subject string can be requested -by the /g or /G modifier. After finding a match, PCRE is called -again to search the remainder of the subject string. The difference between -/g and /G is that the former uses the startoffset argument to -pcre_exec() to start searching at a new point within the entire string -(which is in effect what Perl does), whereas the latter passes over a shortened -substring. This makes a difference to the matching process if the pattern -begins with a lookbehind assertion (including \b or \B). -

-

-If any call to pcre_exec() in a /g or /G sequence matches an -empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED -flags set in order to search for another, non-empty, match at the same point. -If this second match fails, the start offset is advanced by one, and the normal -match is retried. This imitates the way Perl handles such cases when using the -/g modifier or the split() function. -

-

-There are yet more modifiers for controlling the way pcretest -operates. -

-

-The /+ modifier requests that as well as outputting the substring that -matched the entire pattern, pcretest should in addition output the remainder of -the subject string. This is useful for tests where the subject contains -multiple copies of the same substring. -

-

-The /L modifier must be followed directly by the name of a locale, for -example, -

-  /pattern/Lfr_FR
-
-For this reason, it must be the last modifier. The given locale is set, -pcre_maketables() is called to build a set of character tables for the -locale, and this is then passed to pcre_compile() when compiling the -regular expression. Without an /L modifier, NULL is passed as the tables -pointer; that is, /L applies only to the expression on which it appears. -

-

-The /I modifier requests that pcretest output information about the -compiled pattern (whether it is anchored, has a fixed first character, and -so on). It does this by calling pcre_fullinfo() after compiling a -pattern. If the pattern is studied, the results of that are also output. -

-

-The /D modifier is a PCRE debugging feature, which also assumes /I. -It causes the internal form of compiled regular expressions to be output after -compilation. If the pattern was studied, the information returned is also -output. -

-

-The /F modifier causes pcretest to flip the byte order of the -fields in the compiled pattern that contain 2-byte and 4-byte numbers. This -facility is for testing the feature in PCRE that allows it to execute patterns -that were compiled on a host with a different endianness. This feature is not -available when the POSIX interface to PCRE is being used, that is, when the -/P pattern modifier is specified. See also the section about saving and -reloading compiled patterns below. -

-

-The /S modifier causes pcre_study() to be called after the -expression has been compiled, and the results used when the expression is -matched. -

-

-The /M modifier causes the size of memory block used to hold the compiled -pattern to be output. -

-

-The /P modifier causes pcretest to call PCRE via the POSIX wrapper -API rather than its native API. When this is done, all other modifiers except -/i, /m, and /+ are ignored. REG_ICASE is set if /i is -present, and REG_NEWLINE is set if /m is present. The wrapper functions -force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. -

-

-The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 -option set. This turns on support for UTF-8 character handling in PCRE, -provided that it was compiled with this support enabled. This modifier also -causes any non-printing characters in output strings to be printed using the -\x{hh...} notation if they are valid UTF-8 sequences. -

-

-If the /? modifier is used with /8, it causes pcretest to -call pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the -checking of the string for UTF-8 validity. -

-
DATA LINES
-

-Before each data line is passed to pcre_exec(), leading and trailing -whitespace is removed, and it is then scanned for \ escapes. Some of these are -pretty esoteric features, intended for checking out some of the more -complicated features of PCRE. If you are just testing "ordinary" regular -expressions, you probably don't need any of these. The following escapes are -recognized: -

-  \a         alarm (= BEL)
-  \b         backspace
-  \e         escape
-  \f         formfeed
-  \n         newline
-  \r         carriage return
-  \t         tab
-  \v         vertical tab
-  \nnn       octal character (up to 3 octal digits)
-  \xhh       hexadecimal character (up to 2 hex digits)
-  \x{hh...}  hexadecimal character, any number of digits in UTF-8 mode
-  \A         pass the PCRE_ANCHORED option to pcre_exec()
-  \B         pass the PCRE_NOTBOL option to pcre_exec()
-  \Cdd       call pcre_copy_substring() for substring dd after a successful match (number less than 32)
-  \Cname     call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
-               ated by next non alphanumeric character)
-  \C+        show the current captured substrings at callout time
-  \C-        do not supply a callout function
-  \C!n       return 1 instead of 0 when callout number n is reached
-  \C!n!m     return 1 instead of 0 when callout number n is reached for the nth time
-  \C*n       pass the number n (may be negative) as callout data; this is used as the callout return value
-  \Gdd       call pcre_get_substring() for substring dd after a successful match (number less than 32)
-  \Gname     call pcre_get_named_substring() for substring "name" after a successful match (name termin-
-               ated by next non-alphanumeric character)
-  \L         call pcre_get_substringlist() after a successful match
-  \M         discover the minimum MATCH_LIMIT setting
-  \N         pass the PCRE_NOTEMPTY option to pcre_exec()
-  \Odd       set the size of the output vector passed to pcre_exec() to dd (any number of digits)
-  \P         pass the PCRE_PARTIAL option to pcre_exec()
-  \S         output details of memory get/free calls during matching
-  \Z         pass the PCRE_NOTEOL option to pcre_exec()
-  \?         pass the PCRE_NO_UTF8_CHECK option to pcre_exec()
-  \>dd       start the match at offset dd (any number of digits);
-               this sets the startoffset argument for pcre_exec()
-
-A backslash followed by anything else just escapes the anything else. If the -very last character is a backslash, it is ignored. This gives a way of passing -an empty line as data, since a real empty line terminates the data input. -

-

-If \M is present, pcretest calls pcre_exec() several times, with -different values in the match_limit field of the pcre_extra data -structure, until it finds the minimum number that is needed for -pcre_exec() to complete. This number is a measure of the amount of -recursion and backtracking that takes place, and checking it out can be -instructive. For most simple matches, the number is quite small, but for -patterns with very large numbers of matching possibilities, it can become large -very quickly with increasing length of subject string. -

-

-When \O is used, the value specified may be higher or lower than the size set -by the -O command line option (or defaulted to 45); \O applies only to -the call of pcre_exec() for the line in which it appears. -

-

-If the /P modifier was present on the pattern, causing the POSIX wrapper -API to be used, only \B and \Z have any effect, causing REG_NOTBOL and -REG_NOTEOL to be passed to regexec() respectively. -

-

-The use of \x{hh...} to represent UTF-8 characters is not dependent on the use -of the /8 modifier on the pattern. It is recognized always. There may be -any number of hexadecimal digits inside the braces. The result is from one to -six bytes, encoded according to the UTF-8 rules. -

-
OUTPUT FROM PCRETEST
-

-When a match succeeds, pcretest outputs the list of captured substrings that -pcre_exec() returns, starting with number 0 for the string that matched -the whole pattern. Otherwise, it outputs "No match" or "Partial match" -when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL, -respectively, and otherwise the PCRE negative error number. Here is an example -of an interactive pcretest run. -

-  $ pcretest
-  PCRE version 5.00 07-Sep-2004
-
-    re> /^abc(\d+)/
-  data> abc123
-   0: abc123
-   1: 123
-  data> xyz
-  No match
-
-If the strings contain any non-printing characters, they are output as \0x -escapes, or as \x{...} escapes if the /8 modifier was present on the -pattern. If the pattern has the /+ modifier, the output for substring 0 -is followed by the the rest of the subject string, identified by "0+" like -this: -
-    re> /cat/+
-  data> cataract
-   0: cat
-   0+ aract
-
-If the pattern has the /g or /G modifier, the results of successive -matching attempts are output in sequence, like this: -
-    re> /\Bi(\w\w)/g
-  data> Mississippi
-   0: iss
-   1: ss
-   0: iss
-   1: ss
-   0: ipp
-   1: pp
-
-"No match" is output only if the first match attempt fails. -

-

-If any of the sequences \C, \G, or \L are present in a -data line that is successfully matched, the substrings extracted by the -convenience functions are output with C, G, or L after the string number -instead of a colon. This is in addition to the normal full list. The string -length (that is, the return from the extraction function) is given in -parentheses after each string for \C and \G. -

-

-Note that while patterns can be continued over several lines (a plain ">" -prompt is used for continuations), data lines may not. However newlines can be -included in data by means of the \n escape. -

-
CALLOUTS
-

-If the pattern contains any callout requests, pcretest's callout function -is called during matching. By default, it displays the callout number, the -start and current positions in the text at the callout time, and the next -pattern item to be tested. For example, the output -

-  --->pqrabcdef
-    0    ^  ^     \d
-
-indicates that callout number 0 occurred for a match attempt starting at the -fourth character of the subject string, when the pointer was at the seventh -character of the data, and when the next pattern item was \d. Just one -circumflex is output if the start and current positions are the same. -

-

-Callouts numbered 255 are assumed to be automatic callouts, inserted as a -result of the /C pattern modifier. In this case, instead of showing the -callout number, the offset in the pattern, preceded by a plus, is output. For -example: -

-    re> /\d?[A-E]\*/C
-  data> E*
-  --->E*
-   +0 ^      \d?
-   +3 ^      [A-E]
-   +8 ^^     \*
-  +10 ^ ^
-   0: E*
-
-The callout function in pcretest returns zero (carry on matching) by -default, but you can use an \C item in a data line (as described above) to -change this. -

-

-Inserting callouts can be helpful when using pcretest to check -complicated regular expressions. For further information about callouts, see -the -pcrecallout -documentation. -

-
SAVING AND RELOADING COMPILED PATTERNS
-

-The facilities described in this section are not available when the POSIX -inteface to PCRE is being used, that is, when the /P pattern modifier is -specified. -

-

-When the POSIX interface is not in use, you can cause pcretest to write a -compiled pattern to a file, by following the modifiers with > and a file name. -For example: -

-  /pattern/im >/some/file
-
-See the -pcreprecompile -documentation for a discussion about saving and re-using compiled patterns. -

-

-The data that is written is binary. The first eight bytes are the length of the -compiled pattern data followed by the length of the optional study data, each -written as four bytes in big-endian order (most significant byte first). If -there is no study data (either the pattern was not studied, or studying did not -return any data), the second length is zero. The lengths are followed by an -exact copy of the compiled pattern. If there is additional study data, this -follows immediately after the compiled pattern. After writing the file, -pcretest expects to read a new pattern. -

-

-A saved pattern can be reloaded into pcretest by specifing < and a file -name instead of a pattern. The name of the file must not contain a < character, -as otherwise pcretest will interpret the line as a pattern delimited by < -characters. -For example: -

-   re> </some/file
-  Compiled regex loaded from /some/file
-  No study data
-
-When the pattern has been loaded, pcretest proceeds to read data lines in -the usual way. -

-

-You can copy a file written by pcretest to a different host and reload it -there, even if the new host has opposite endianness to the one on which the -pattern was compiled. For example, you can compile on an i86 machine and run on -a SPARC machine. -

-

-File names for saving and reloading can be absolute or relative, but note that -the shell facility of expanding a file name that starts with a tilde (~) is not -available. -

-

-The ability to save and reload files in pcretest is intended for testing -and experimentation. It is not intended for production use because only a -single pattern can be written to a file. Furthermore, there is no facility for -supplying custom character tables for use with a reloaded pattern. If the -original pattern was compiled with custom tables, an attempt to match a subject -string using a reloaded pattern is likely to cause pcretest to crash. -Finally, if you attempt to load a file that is not in the correct format, the -result is undefined. -

-
AUTHOR
-

-Philip Hazel <ph10@cam.ac.uk> -
-University Computing Service, -
-Cambridge CB2 3QG, England. -

-

-Last updated: 10 September 2004 -
-Copyright © 1997-2004 University of Cambridge. -

-Return to the PCRE index page. -

diff --git a/srclib/pcre/doc/pcre.3 b/srclib/pcre/doc/pcre.3 deleted file mode 100644 index 54b0c3359b..0000000000 --- a/srclib/pcre/doc/pcre.3 +++ /dev/null @@ -1,204 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH INTRODUCTION -.rs -.sp -The PCRE library is a set of functions that implement regular expression -pattern matching using the same syntax and semantics as Perl, with just a few -differences. The current implementation of PCRE (release 5.x) corresponds -approximately with Perl 5.8, including support for UTF-8 encoded strings and -Unicode general category properties. However, this support has to be explicitly -enabled; it is not the default. -.P -PCRE is written in C and released as a C library. A number of people have -written wrappers and interfaces of various kinds. A C++ class is included in -these contributions, which can be found in the \fIContrib\fR directory at the -primary FTP site, which is: -.sp -.\" HTML -.\" -ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre -.P -Details of exactly which Perl regular expression features are and are not -supported by PCRE are given in separate documents. See the -.\" HREF -\fBpcrepattern\fR -.\" -and -.\" HREF -\fBpcrecompat\fR -.\" -pages. -.P -Some features of PCRE can be included, excluded, or changed when the library is -built. The -.\" HREF -\fBpcre_config()\fR -.\" -function makes it possible for a client to discover which features are -available. The features themselves are described in the -.\" HREF -\fBpcrebuild\fP -.\" -page. Documentation about building PCRE for various operating systems can be -found in the \fBREADME\fP file in the source distribution. -. -. -.SH "USER DOCUMENTATION" -.rs -.sp -The user documentation for PCRE comprises a number of different sections. In -the "man" format, each of these is a separate "man page". In the HTML format, -each is a separate page, linked from the index page. In the plain text format, -all the sections are concatenated, for ease of searching. The sections are as -follows: -.sp - pcre this document - pcreapi details of PCRE's native API - pcrebuild options for building PCRE - pcrecallout details of the callout feature - pcrecompat discussion of Perl compatibility - pcregrep description of the \fBpcregrep\fP command - pcrepartial details of the partial matching facility -.\" JOIN - pcrepattern syntax and semantics of supported - regular expressions - pcreperform discussion of performance issues - pcreposix the POSIX-compatible API - pcreprecompile details of saving and re-using precompiled patterns - pcresample discussion of the sample program - pcretest description of the \fBpcretest\fP testing command -.sp -In addition, in the "man" and HTML formats, there is a short page for each -library function, listing its arguments and results. -. -. -.SH LIMITATIONS -.rs -.sp -There are some size limitations in PCRE but it is hoped that they will never in -practice be relevant. -.P -The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is -compiled with the default internal linkage size of 2. If you want to process -regular expressions that are truly enormous, you can compile PCRE with an -internal linkage size of 3 or 4 (see the \fBREADME\fP file in the source -distribution and the -.\" HREF -\fBpcrebuild\fP -.\" -documentation for details). In these cases the limit is substantially larger. -However, the speed of execution will be slower. -.P -All values in repeating quantifiers must be less than 65536. -The maximum number of capturing subpatterns is 65535. -.P -There is no limit to the number of non-capturing subpatterns, but the maximum -depth of nesting of all kinds of parenthesized subpattern, including capturing -subpatterns, assertions, and other types of subpattern, is 200. -.P -The maximum length of a subject string is the largest positive number that an -integer variable can hold. However, PCRE uses recursion to handle subpatterns -and indefinite repetition. This means that the available stack space may limit -the size of a subject string that can be processed by certain patterns. -.sp -.\" HTML -. -. -.SH "UTF-8 AND UNICODE PROPERTY SUPPORT" -.rs -.sp -From release 3.3, PCRE has had some support for character strings encoded in -the UTF-8 format. For release 4.0 this was greatly extended to cover most -common requirements, and in release 5.0 additional support for Unicode general -category properties was added. -.P -In order process UTF-8 strings, you must build PCRE to include UTF-8 support in -the code, and, in addition, you must call -.\" HREF -\fBpcre_compile()\fP -.\" -with the PCRE_UTF8 option flag. When you do this, both the pattern and any -subject strings that are matched against it are treated as UTF-8 strings -instead of just strings of bytes. -.P -If you compile PCRE with UTF-8 support, but do not use it at run time, the -library will be a bit bigger, but the additional run time overhead is limited -to testing the PCRE_UTF8 flag in several places, so should not be very large. -.P -If PCRE is built with Unicode character property support (which implies UTF-8 -support), the escape sequences \ep{..}, \eP{..}, and \eX are supported. -The available properties that can be tested are limited to the general -category properties such as Lu for an upper case letter or Nd for a decimal -number. A full list is given in the -.\" HREF -\fBpcrepattern\fP -.\" -documentation. The PCRE library is increased in size by about 90K when Unicode -property support is included. -.P -The following comments apply when PCRE is running in UTF-8 mode: -.P -1. When you set the PCRE_UTF8 flag, the strings passed as patterns and subjects -are checked for validity on entry to the relevant functions. If an invalid -UTF-8 string is passed, an error return is given. In some situations, you may -already know that your strings are valid, and therefore want to skip these -checks in order to improve performance. If you set the PCRE_NO_UTF8_CHECK flag -at compile time or at run time, PCRE assumes that the pattern or subject it -is given (respectively) contains only valid UTF-8 codes. In this case, it does -not diagnose an invalid UTF-8 string. If you pass an invalid UTF-8 string to -PCRE when PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program -may crash. -.P -2. In a pattern, the escape sequence \ex{...}, where the contents of the braces -is a string of hexadecimal digits, is interpreted as a UTF-8 character whose -code number is the given hexadecimal number, for example: \ex{1234}. If a -non-hexadecimal digit appears between the braces, the item is not recognized. -This escape sequence can be used either as a literal, or within a character -class. -.P -3. The original hexadecimal escape sequence, \exhh, matches a two-byte UTF-8 -character if the value is greater than 127. -.P -4. Repeat quantifiers apply to complete UTF-8 characters, not to individual -bytes, for example: \ex{100}{3}. -.P -5. The dot metacharacter matches one UTF-8 character instead of a single byte. -.P -6. The escape sequence \eC can be used to match a single byte in UTF-8 mode, -but its use can lead to some strange effects. -.P -7. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly -test characters of any code value, but the characters that PCRE recognizes as -digits, spaces, or word characters remain the same set as before, all with -values less than 256. This remains true even when PCRE includes Unicode -property support, because to do otherwise would slow down PCRE in many common -cases. If you really want to test for a wider sense of, say, "digit", you -must use Unicode property tests such as \ep{Nd}. -.P -8. Similarly, characters that match the POSIX named character classes are all -low-valued characters. -.P -9. Case-insensitive matching applies only to characters whose values are less -than 128, unless PCRE is built with Unicode property support. Even when Unicode -property support is available, PCRE still uses its own character tables when -checking the case of low-valued characters, so as not to degrade performance. -The Unicode property information is used only for characters with higher -values. -. -.SH AUTHOR -.rs -.sp -Philip Hazel -.br -University Computing Service, -.br -Cambridge CB2 3QG, England. -.br -Phone: +44 1223 334714 -.sp -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcre.html b/srclib/pcre/doc/pcre.html deleted file mode 100644 index 3e9eb36b68..0000000000 --- a/srclib/pcre/doc/pcre.html +++ /dev/null @@ -1,2669 +0,0 @@ - - -pcre specification - - -

pcre specification

-This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page in case the -conversion went wrong. - -
  • NAME -

    -pcre - Perl-compatible regular expressions. -

    -
  • SYNOPSIS -

    -#include <pcre.h> -

    -

    -pcre *pcre_compile(const char *pattern, int options, -const char **errptr, int *erroffset, -const unsigned char *tableptr); -

    -

    -pcre_extra *pcre_study(const pcre *code, int options, -const char **errptr); -

    -

    -int pcre_exec(const pcre *code, const pcre_extra *extra, -const char *subject, int length, int startoffset, -int options, int *ovector, int ovecsize); -

    -

    -int pcre_copy_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, char *buffer, -int buffersize); -

    -

    -int pcre_get_substring(const char *subject, int *ovector, -int stringcount, int stringnumber, -const char **stringptr); -

    -

    -int pcre_get_substring_list(const char *subject, -int *ovector, int stringcount, const char ***listptr); -

    -

    -void pcre_free_substring(const char *stringptr); -

    -

    -void pcre_free_substring_list(const char **stringptr); -

    -

    -const unsigned char *pcre_maketables(void); -

    -

    -int pcre_fullinfo(const pcre *code, const pcre_extra *extra, -int what, void *where); -

    -

    -int pcre_info(const pcre *code, int *optptr, int -*firstcharptr); -

    -

    -char *pcre_version(void); -

    -

    -void *(*pcre_malloc)(size_t); -

    -

    -void (*pcre_free)(void *); -

    -
  • DESCRIPTION -

    -The PCRE library is a set of functions that implement regular expression -pattern matching using the same syntax and semantics as Perl 5, with just a few -differences (see below). The current implementation corresponds to Perl 5.005, -with some additional features from later versions. This includes some -experimental, incomplete support for UTF-8 encoded strings. Details of exactly -what is and what is not supported are given below. -

    -

    -PCRE has its own native API, which is described in this document. There is also -a set of wrapper functions that correspond to the POSIX regular expression API. -These are described in the pcreposix documentation. -

    -

    -The native API function prototypes are defined in the header file pcre.h, -and on Unix systems the library itself is called libpcre.a, so can be -accessed by adding -lpcre to the command for linking an application which -calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to -contain the major and minor release numbers for the library. Applications can -use these to include support for different releases. -

    -

    -The functions pcre_compile(), pcre_study(), and pcre_exec() -are used for compiling and matching regular expressions. A sample program that -demonstrates the simplest way of using them is given in the file -pcredemo.c. The last section of this man page describes how to run it. -

    -

    -The functions pcre_copy_substring(), pcre_get_substring(), and -pcre_get_substring_list() are convenience functions for extracting -captured substrings from a matched subject string; pcre_free_substring() -and pcre_free_substring_list() are also provided, to free the memory used -for extracted strings. -

    -

    -The function pcre_maketables() is used (optionally) to build a set of -character tables in the current locale for passing to pcre_compile(). -

    -

    -The function pcre_fullinfo() is used to find out information about a -compiled pattern; pcre_info() is an obsolete version which returns only -some of the available information, but is retained for backwards compatibility. -The function pcre_version() returns a pointer to a string containing the -version of PCRE and its date of release. -

    -

    -The global variables pcre_malloc and pcre_free initially contain -the entry points of the standard malloc() and free() functions -respectively. PCRE calls the memory management functions via these variables, -so a calling program can replace them if it wishes to intercept the calls. This -should be done before calling any PCRE functions. -

    -
  • MULTI-THREADING -

    -The PCRE functions can be used in multi-threading applications, with the -proviso that the memory management functions pointed to by pcre_malloc -and pcre_free are shared by all threads. -

    -

    -The compiled form of a regular expression is not altered during matching, so -the same compiled pattern can safely be used by several threads at once. -

    -
  • COMPILING A PATTERN -

    -The function pcre_compile() is called to compile a pattern into an -internal form. The pattern is a C string terminated by a binary zero, and -is passed in the argument pattern. A pointer to a single block of memory -that is obtained via pcre_malloc is returned. This contains the compiled -code and related data. The pcre type is defined for the returned block; -this is a typedef for a structure whose contents are not externally defined. It -is up to the caller to free the memory when it is no longer required. -

    -

    -Although the compiled code of a PCRE regex is relocatable, that is, it does not -depend on memory location, the complete pcre data block is not -fully relocatable, because it contains a copy of the tableptr argument, -which is an address (see below). -

    -

    -The size of a compiled pattern is roughly proportional to the length of the -pattern string, except that each character class (other than those containing -just a single character, negated or not) requires 33 bytes, and repeat -quantifiers with a minimum greater than one or a bounded maximum cause the -relevant portions of the compiled pattern to be replicated. -

    -

    -The options argument contains independent bits that affect the -compilation. It should be zero if no options are required. Some of the options, -in particular, those that are compatible with Perl, can also be set and unset -from within the pattern (see the detailed description of regular expressions -below). For these options, the contents of the options argument specifies -their initial settings at the start of compilation and execution. The -PCRE_ANCHORED option can be set at the time of matching as well as at compile -time. -

    -

    -If errptr is NULL, pcre_compile() returns NULL immediately. -Otherwise, if compilation of a pattern fails, pcre_compile() returns -NULL, and sets the variable pointed to by errptr to point to a textual -error message. The offset from the start of the pattern to the character where -the error was discovered is placed in the variable pointed to by -erroffset, which must not be NULL. If it is, an immediate error is given. -

    -

    -If the final argument, tableptr, is NULL, PCRE uses a default set of -character tables which are built when it is compiled, using the default C -locale. Otherwise, tableptr must be the result of a call to -pcre_maketables(). See the section on locale support below. -

    -

    -This code fragment shows a typical straightforward call to pcre_compile(): -

    -

    -

    -  pcre *re;
-  const char *error;
-  int erroffset;
-  re = pcre_compile(
-    "^A.*Z",          /* the pattern */
-    0,                /* default options */
-    &error,           /* for error message */
-    &erroffset,       /* for error offset */
-    NULL);            /* use default character tables */
-
    -

    -

    -The following option bits are defined in the header file: -

    -

    -

    -  PCRE_ANCHORED
-
    -

    -

    -If this bit is set, the pattern is forced to be "anchored", that is, it is -constrained to match only at the start of the string which is being searched -(the "subject string"). This effect can also be achieved by appropriate -constructs in the pattern itself, which is the only way to do it in Perl. -

    -

    -

    -  PCRE_CASELESS
-
    -

    -

    -If this bit is set, letters in the pattern match both upper and lower case -letters. It is equivalent to Perl's /i option. -

    -

    -

    -  PCRE_DOLLAR_ENDONLY
-
    -

    -

    -If this bit is set, a dollar metacharacter in the pattern matches only at the -end of the subject string. Without this option, a dollar also matches -immediately before the final character if it is a newline (but not before any -other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is -set. There is no equivalent to this option in Perl. -

    -

    -

    -  PCRE_DOTALL
-
    -

    -

    -If this bit is set, a dot metacharater in the pattern matches all characters, -including newlines. Without it, newlines are excluded. This option is -equivalent to Perl's /s option. A negative class such as [^a] always matches a -newline character, independent of the setting of this option. -

    -

    -

    -  PCRE_EXTENDED
-
    -

    -

    -If this bit is set, whitespace data characters in the pattern are totally -ignored except when escaped or inside a character class, and characters between -an unescaped # outside a character class and the next newline character, -inclusive, are also ignored. This is equivalent to Perl's /x option, and makes -it possible to include comments inside complicated patterns. Note, however, -that this applies only to data characters. Whitespace characters may never -appear within special character sequences in a pattern, for example within the -sequence (?( which introduces a conditional subpattern. -

    -

    -

    -  PCRE_EXTRA
-
    -

    -

    -This option was invented in order to turn on additional functionality of PCRE -that is incompatible with Perl, but it is currently of very little use. When -set, any backslash in a pattern that is followed by a letter that has no -special meaning causes an error, thus reserving these combinations for future -expansion. By default, as in Perl, a backslash followed by a letter with no -special meaning is treated as a literal. There are at present no other features -controlled by this option. It can also be set by a (?X) option setting within a -pattern. -

    -

    -

    -  PCRE_MULTILINE
-
    -

    -

    -By default, PCRE treats the subject string as consisting of a single "line" of -characters (even if it actually contains several newlines). The "start of line" -metacharacter (^) matches only at the start of the string, while the "end of -line" metacharacter ($) matches only at the end of the string, or before a -terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as -Perl. -

    -

    -When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs -match immediately following or immediately before any newline in the subject -string, respectively, as well as at the very start and end. This is equivalent -to Perl's /m option. If there are no "\n" characters in a subject string, or -no occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no -effect. -

    -

    -

    -  PCRE_UNGREEDY
-
    -

    -

    -This option inverts the "greediness" of the quantifiers so that they are not -greedy by default, but become greedy if followed by "?". It is not compatible -with Perl. It can also be set by a (?U) option setting within the pattern. -

    -

    -

    -  PCRE_UTF8
-
    -

    -

    -This option causes PCRE to regard both the pattern and the subject as strings -of UTF-8 characters instead of just byte strings. However, it is available only -if PCRE has been built to include UTF-8 support. If not, the use of this option -provokes an error. Support for UTF-8 is new, experimental, and incomplete. -Details of exactly what it entails are given below. -

    -
  • STUDYING A PATTERN -

    -When a pattern is going to be used several times, it is worth spending more -time analyzing it in order to speed up the time taken for matching. The -function pcre_study() takes a pointer to a compiled pattern as its first -argument, and returns a pointer to a pcre_extra block (another typedef -for a structure with hidden contents) containing additional information about -the pattern; this can be passed to pcre_exec(). If no additional -information is available, NULL is returned. -

    -

    -The second argument contains option bits. At present, no options are defined -for pcre_study(), and this argument should always be zero. -

    -

    -The third argument for pcre_study() is a pointer to an error message. If -studying succeeds (even if no data is returned), the variable it points to is -set to NULL. Otherwise it points to a textual error message. -

    -

    -This is a typical call to pcre_study(): -

    -

    -

    -  pcre_extra *pe;
-  pe = pcre_study(
-    re,             /* result of pcre_compile() */
-    0,              /* no options exist */
-    &error);        /* set to NULL or points to a message */
-
    -

    -

    -At present, studying a pattern is useful only for non-anchored patterns that do -not have a single fixed starting character. A bitmap of possible starting -characters is created. -

    -
  • LOCALE SUPPORT -

    -PCRE handles caseless matching, and determines whether characters are letters, -digits, or whatever, by reference to a set of tables. The library contains a -default set of tables which is created in the default C locale when PCRE is -compiled. This is used when the final argument of pcre_compile() is NULL, -and is sufficient for many applications. -

    -

    -An alternative set of tables can, however, be supplied. Such tables are built -by calling the pcre_maketables() function, which has no arguments, in the -relevant locale. The result can then be passed to pcre_compile() as often -as necessary. For example, to build and use tables that are appropriate for the -French locale (where accented characters with codes greater than 128 are -treated as letters), the following code could be used: -

    -

    -

    -  setlocale(LC_CTYPE, "fr");
-  tables = pcre_maketables();
-  re = pcre_compile(..., tables);
-
    -

    -

    -The tables are built in memory that is obtained via pcre_malloc. The -pointer that is passed to pcre_compile is saved with the compiled -pattern, and the same tables are used via this pointer by pcre_study() -and pcre_exec(). Thus for any single pattern, compilation, studying and -matching all happen in the same locale, but different patterns can be compiled -in different locales. It is the caller's responsibility to ensure that the -memory containing the tables remains available for as long as it is needed. -

    -
  • INFORMATION ABOUT A PATTERN -

    -The pcre_fullinfo() function returns information about a compiled -pattern. It replaces the obsolete pcre_info() function, which is -nevertheless retained for backwards compability (and is documented below). -

    -

    -The first argument for pcre_fullinfo() is a pointer to the compiled -pattern. The second argument is the result of pcre_study(), or NULL if -the pattern was not studied. The third argument specifies which piece of -information is required, while the fourth argument is a pointer to a variable -to receive the data. The yield of the function is zero for success, or one of -the following negative numbers: -

    -

    -

    -  PCRE_ERROR_NULL       the argument code was NULL
-                        the argument where was NULL
-  PCRE_ERROR_BADMAGIC   the "magic number" was not found
-  PCRE_ERROR_BADOPTION  the value of what was invalid
-
    -

    -

    -Here is a typical call of pcre_fullinfo(), to obtain the length of the -compiled pattern: -

    -

    -

    -  int rc;
-  unsigned long int length;
-  rc = pcre_fullinfo(
-    re,               /* result of pcre_compile() */
-    pe,               /* result of pcre_study(), or NULL */
-    PCRE_INFO_SIZE,   /* what is required */
-    &length);         /* where to put the data */
-
    -

    -

    -The possible values for the third argument are defined in pcre.h, and are -as follows: -

    -

    -

    -  PCRE_INFO_OPTIONS
-
    -

    -

    -Return a copy of the options with which the pattern was compiled. The fourth -argument should point to an unsigned long int variable. These option bits -are those specified in the call to pcre_compile(), modified by any -top-level option settings within the pattern itself, and with the PCRE_ANCHORED -bit forcibly set if the form of the pattern implies that it can match only at -the start of a subject string. -

    -

    -

    -  PCRE_INFO_SIZE
-
    -

    -

    -Return the size of the compiled pattern, that is, the value that was passed as -the argument to pcre_malloc() when PCRE was getting memory in which to -place the compiled data. The fourth argument should point to a size_t -variable. -

    -

    -

    -  PCRE_INFO_CAPTURECOUNT
-
    -

    -

    -Return the number of capturing subpatterns in the pattern. The fourth argument -should point to an \fbint\fR variable. -

    -

    -

    -  PCRE_INFO_BACKREFMAX
-
    -

    -

    -Return the number of the highest back reference in the pattern. The fourth -argument should point to an int variable. Zero is returned if there are -no back references. -

    -

    -

    -  PCRE_INFO_FIRSTCHAR
-
    -

    -

    -Return information about the first character of any matched string, for a -non-anchored pattern. If there is a fixed first character, e.g. from a pattern -such as (cat|cow|coyote), it is returned in the integer pointed to by -where. Otherwise, if either -

    -

    -(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch -starts with "^", or -

    -

    -(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set -(if it were set, the pattern would be anchored), -

    -

    --1 is returned, indicating that the pattern matches only at the start of a -subject string or after any "\n" within the string. Otherwise -2 is returned. -For anchored patterns, -2 is returned. -

    -

    -

    -  PCRE_INFO_FIRSTTABLE
-
    -

    -

    -If the pattern was studied, and this resulted in the construction of a 256-bit -table indicating a fixed set of characters for the first character in any -matching string, a pointer to the table is returned. Otherwise NULL is -returned. The fourth argument should point to an unsigned char * -variable. -

    -

    -

    -  PCRE_INFO_LASTLITERAL
-
    -

    -

    -For a non-anchored pattern, return the value of the rightmost literal character -which must exist in any matched string, other than at its start. The fourth -argument should point to an int variable. If there is no such character, -or if the pattern is anchored, -1 is returned. For example, for the pattern -/a\d+z\d+/ the returned value is 'z'. -

    -

    -The pcre_info() function is now obsolete because its interface is too -restrictive to return all the available data about a compiled pattern. New -programs should use pcre_fullinfo() instead. The yield of -pcre_info() is the number of capturing subpatterns, or one of the -following negative numbers: -

    -

    -

    -  PCRE_ERROR_NULL       the argument code was NULL
-  PCRE_ERROR_BADMAGIC   the "magic number" was not found
-
    -

    -

    -If the optptr argument is not NULL, a copy of the options with which the -pattern was compiled is placed in the integer it points to (see -PCRE_INFO_OPTIONS above). -

    -

    -If the pattern is not anchored and the firstcharptr argument is not NULL, -it is used to pass back information about the first character of any matched -string (see PCRE_INFO_FIRSTCHAR above). -

    -
  • MATCHING A PATTERN -

    -The function pcre_exec() is called to match a subject string against a -pre-compiled pattern, which is passed in the code argument. If the -pattern has been studied, the result of the study should be passed in the -extra argument. Otherwise this must be NULL. -

    -

    -Here is an example of a simple call to pcre_exec(): -

    -

    -

    -  int rc;
-  int ovector[30];
-  rc = pcre_exec(
-    re,             /* result of pcre_compile() */
-    NULL,           /* we didn't study the pattern */
-    "some string",  /* the subject string */
-    11,             /* the length of the subject string */
-    0,              /* start at offset 0 in the subject */
-    0,              /* default options */
-    ovector,        /* vector for substring information */
-    30);            /* number of elements in the vector */
-
    -

    -

    -The PCRE_ANCHORED option can be passed in the options argument, whose -unused bits must be zero. However, if a pattern was compiled with -PCRE_ANCHORED, or turned out to be anchored by virtue of its contents, it -cannot be made unachored at matching time. -

    -

    -There are also three further options that can be set only at matching time: -

    -

    -

    -  PCRE_NOTBOL
-
    -

    -

    -The first character of the string is not the beginning of a line, so the -circumflex metacharacter should not match before it. Setting this without -PCRE_MULTILINE (at compile time) causes circumflex never to match. -

    -

    -

    -  PCRE_NOTEOL
-
    -

    -

    -The end of the string is not the end of a line, so the dollar metacharacter -should not match it nor (except in multiline mode) a newline immediately before -it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never -to match. -

    -

    -

    -  PCRE_NOTEMPTY
-
    -

    -

    -An empty string is not considered to be a valid match if this option is set. If -there are alternatives in the pattern, they are tried. If all the alternatives -match the empty string, the entire match fails. For example, if the pattern -

    -

    -

    -  a?b?
-
    -

    -

    -is applied to a string not beginning with "a" or "b", it matches the empty -string at the start of the subject. With PCRE_NOTEMPTY set, this match is not -valid, so PCRE searches further into the string for occurrences of "a" or "b". -

    -

    -Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case -of a pattern match of the empty string within its split() function, and -when using the /g modifier. It is possible to emulate Perl's behaviour after -matching a null string by first trying the match again at the same offset with -PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see -below) and trying an ordinary match again. -

    -

    -The subject string is passed as a pointer in subject, a length in -length, and a starting offset in startoffset. Unlike the pattern -string, the subject may contain binary zero characters. When the starting -offset is zero, the search for a match starts at the beginning of the subject, -and this is by far the most common case. -

    -

    -A non-zero starting offset is useful when searching for another match in the -same subject by calling pcre_exec() again after a previous success. -Setting startoffset differs from just passing over a shortened string and -setting PCRE_NOTBOL in the case of a pattern that begins with any kind of -lookbehind. For example, consider the pattern -

    -

    -

    -  \Biss\B
-
    -

    -

    -which finds occurrences of "iss" in the middle of words. (\B matches only if -the current position in the subject is not a word boundary.) When applied to -the string "Mississipi" the first call to pcre_exec() finds the first -occurrence. If pcre_exec() is called again with just the remainder of the -subject, namely "issipi", it does not match, because \B is always false at the -start of the subject, which is deemed to be a word boundary. However, if -pcre_exec() is passed the entire string again, but with startoffset -set to 4, it finds the second occurrence of "iss" because it is able to look -behind the starting point to discover that it is preceded by a letter. -

    -

    -If a non-zero starting offset is passed when the pattern is anchored, one -attempt to match at the given offset is tried. This can only succeed if the -pattern does not require the match to be at the start of the subject. -

    -

    -In general, a pattern matches a certain portion of the subject, and in -addition, further substrings from the subject may be picked out by parts of the -pattern. Following the usage in Jeffrey Friedl's book, this is called -"capturing" in what follows, and the phrase "capturing subpattern" is used for -a fragment of a pattern that picks out a substring. PCRE supports several other -kinds of parenthesized subpattern that do not cause substrings to be captured. -

    -

    -Captured substrings are returned to the caller via a vector of integer offsets -whose address is passed in ovector. The number of elements in the vector -is passed in ovecsize. The first two-thirds of the vector is used to pass -back captured substrings, each substring using a pair of integers. The -remaining third of the vector is used as workspace by pcre_exec() while -matching capturing subpatterns, and is not available for passing back -information. The length passed in ovecsize should always be a multiple of -three. If it is not, it is rounded down. -

    -

    -When a match has been successful, information about captured substrings is -returned in pairs of integers, starting at the beginning of ovector, and -continuing up to two-thirds of its length at the most. The first element of a -pair is set to the offset of the first character in a substring, and the second -is set to the offset of the first character after the end of a substring. The -first pair, ovector[0] and ovector[1], identify the portion of the -subject string matched by the entire pattern. The next pair is used for the -first capturing subpattern, and so on. The value returned by pcre_exec() -is the number of pairs that have been set. If there are no capturing -subpatterns, the return value from a successful match is 1, indicating that -just the first pair of offsets has been set. -

    -

    -Some convenience functions are provided for extracting the captured substrings -as separate strings. These are described in the following section. -

    -

    -It is possible for an capturing subpattern number n+1 to match some -part of the subject when subpattern n has not been used at all. For -example, if the string "abc" is matched against the pattern (a|(z))(bc) -subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset -values corresponding to the unused subpattern are set to -1. -

    -

    -If a capturing subpattern is matched repeatedly, it is the last portion of the -string that it matched that gets returned. -

    -

    -If the vector is too small to hold all the captured substrings, it is used as -far as possible (up to two-thirds of its length), and the function returns a -value of zero. In particular, if the substring offsets are not of interest, -pcre_exec() may be called with ovector passed as NULL and -ovecsize as zero. However, if the pattern contains back references and -the ovector isn't big enough to remember the related substrings, PCRE has -to get additional memory for use during matching. Thus it is usually advisable -to supply an ovector. -

    -

    -Note that pcre_info() can be used to find out how many capturing -subpatterns there are in a compiled pattern. The smallest size for -ovector that will allow for n captured substrings in addition to -the offsets of the substring matched by the whole pattern is (n+1)*3. -

    -

    -If pcre_exec() fails, it returns a negative number. The following are -defined in the header file: -

    -

    -

    -  PCRE_ERROR_NOMATCH        (-1)
-
    -

    -

    -The subject string did not match the pattern. -

    -

    -

    -  PCRE_ERROR_NULL           (-2)
-
    -

    -

    -Either code or subject was passed as NULL, or ovector was -NULL and ovecsize was not zero. -

    -

    -

    -  PCRE_ERROR_BADOPTION      (-3)
-
    -

    -

    -An unrecognized bit was set in the options argument. -

    -

    -

    -  PCRE_ERROR_BADMAGIC       (-4)
-
    -

    -

    -PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch -the case when it is passed a junk pointer. This is the error it gives when the -magic number isn't present. -

    -

    -

    -  PCRE_ERROR_UNKNOWN_NODE   (-5)
-
    -

    -

    -While running the pattern match, an unknown item was encountered in the -compiled pattern. This error could be caused by a bug in PCRE or by overwriting -of the compiled pattern. -

    -

    -

    -  PCRE_ERROR_NOMEMORY       (-6)
-
    -

    -

    -If a pattern contains back references, but the ovector that is passed to -pcre_exec() is not big enough to remember the referenced substrings, PCRE -gets a block of memory at the start of matching to use for this purpose. If the -call via pcre_malloc() fails, this error is given. The memory is freed at -the end of matching. -

    -
  • EXTRACTING CAPTURED SUBSTRINGS -

    -Captured substrings can be accessed directly by using the offsets returned by -pcre_exec() in ovector. For convenience, the functions -pcre_copy_substring(), pcre_get_substring(), and -pcre_get_substring_list() are provided for extracting captured substrings -as new, separate, zero-terminated strings. A substring that contains a binary -zero is correctly extracted and has a further zero added on the end, but the -result does not, of course, function as a C string. -

    -

    -The first three arguments are the same for all three functions: subject -is the subject string which has just been successfully matched, ovector -is a pointer to the vector of integer offsets that was passed to -pcre_exec(), and stringcount is the number of substrings that -were captured by the match, including the substring that matched the entire -regular expression. This is the value returned by pcre_exec if it -is greater than zero. If pcre_exec() returned zero, indicating that it -ran out of space in ovector, the value passed as stringcount should -be the size of the vector divided by three. -

    -

    -The functions pcre_copy_substring() and pcre_get_substring() -extract a single substring, whose number is given as stringnumber. A -value of zero extracts the substring that matched the entire pattern, while -higher values extract the captured substrings. For pcre_copy_substring(), -the string is placed in buffer, whose length is given by -buffersize, while for pcre_get_substring() a new block of memory is -obtained via pcre_malloc, and its address is returned via -stringptr. The yield of the function is the length of the string, not -including the terminating zero, or one of -

    -

    -

    -  PCRE_ERROR_NOMEMORY       (-6)
-
    -

    -

    -The buffer was too small for pcre_copy_substring(), or the attempt to get -memory failed for pcre_get_substring(). -

    -

    -

    -  PCRE_ERROR_NOSUBSTRING    (-7)
-
    -

    -

    -There is no substring whose number is stringnumber. -

    -

    -The pcre_get_substring_list() function extracts all available substrings -and builds a list of pointers to them. All this is done in a single block of -memory which is obtained via pcre_malloc. The address of the memory block -is returned via listptr, which is also the start of the list of string -pointers. The end of the list is marked by a NULL pointer. The yield of the -function is zero if all went well, or -

    -

    -

    -  PCRE_ERROR_NOMEMORY       (-6)
-
    -

    -

    -if the attempt to get the memory block failed. -

    -

    -When any of these functions encounter a substring that is unset, which can -happen when capturing subpattern number n+1 matches some part of the -subject, but subpattern n has not been used at all, they return an empty -string. This can be distinguished from a genuine zero-length substring by -inspecting the appropriate offset in ovector, which is negative for unset -substrings. -

    -

    -The two convenience functions pcre_free_substring() and -pcre_free_substring_list() can be used to free the memory returned by -a previous call of pcre_get_substring() or -pcre_get_substring_list(), respectively. They do nothing more than call -the function pointed to by pcre_free, which of course could be called -directly from a C program. However, PCRE is used in some situations where it is -linked via a special interface to another programming language which cannot use -pcre_free directly; it is for these cases that the functions are -provided. -

    -
  • LIMITATIONS -

    -There are some size limitations in PCRE but it is hoped that they will never in -practice be relevant. -The maximum length of a compiled pattern is 65539 (sic) bytes. -All values in repeating quantifiers must be less than 65536. -There maximum number of capturing subpatterns is 65535. -There is no limit to the number of non-capturing subpatterns, but the maximum -depth of nesting of all kinds of parenthesized subpattern, including capturing -subpatterns, assertions, and other types of subpattern, is 200. -

    -

    -The maximum length of a subject string is the largest positive number that an -integer variable can hold. However, PCRE uses recursion to handle subpatterns -and indefinite repetition. This means that the available stack space may limit -the size of a subject string that can be processed by certain patterns. -

    -
  • DIFFERENCES FROM PERL -

    -The differences described here are with respect to Perl 5.005. -

    -

    -1. By default, a whitespace character is any character that the C library -function isspace() recognizes, though it is possible to compile PCRE with -alternative character type tables. Normally isspace() matches space, -formfeed, newline, carriage return, horizontal tab, and vertical tab. Perl 5 -no longer includes vertical tab in its set of whitespace characters. The \v -escape that was in the Perl documentation for a long time was never in fact -recognized. However, the character itself was treated as whitespace at least -up to 5.002. In 5.004 and 5.005 it does not match \s. -

    -

    -2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits -them, but they do not mean what you might think. For example, (?!a){3} does -not assert that the next three characters are not "a". It just asserts that the -next character is not "a" three times. -

    -

    -3. Capturing subpatterns that occur inside negative lookahead assertions are -counted, but their entries in the offsets vector are never set. Perl sets its -numerical variables from any such patterns that are matched before the -assertion fails to match something (thereby succeeding), but only if the -negative lookahead assertion contains just one branch. -

    -

    -4. Though binary zero characters are supported in the subject string, they are -not allowed in a pattern string because it is passed as a normal C string, -terminated by zero. The escape sequence "\0" can be used in the pattern to -represent a binary zero. -

    -

    -5. The following Perl escape sequences are not supported: \l, \u, \L, \U, -\E, \Q. In fact these are implemented by Perl's general string-handling and -are not part of its pattern matching engine. -

    -

    -6. The Perl \G assertion is not supported as it is not relevant to single -pattern matches. -

    -

    -7. Fairly obviously, PCRE does not support the (?{code}) and (?p{code}) -constructions. However, there is some experimental support for recursive -patterns using the non-Perl item (?R). -

    -

    -8. There are at the time of writing some oddities in Perl 5.005_02 concerned -with the settings of captured strings when part of a pattern is repeated. For -example, matching "aba" against the pattern /^(a(b)?)+$/ sets $2 to the value -"b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves $2 unset. However, if -the pattern is changed to /^(aa(b(b))?)+$/ then $2 (and $3) are set. -

    -

    -In Perl 5.004 $2 is set in both cases, and that is also true of PCRE. If in the -future Perl changes to a consistent state that is different, PCRE may change to -follow. -

    -

    -9. Another as yet unresolved discrepancy is that in Perl 5.005_02 the pattern -/^(a)?(?(1)a|b)+$/ matches the string "a", whereas in PCRE it does not. -However, in both Perl and PCRE /^(a)?a/ matched against "a" leaves $1 unset. -

    -

    -10. PCRE provides some extensions to the Perl regular expression facilities: -

    -

    -(a) Although lookbehind assertions must match fixed length strings, each -alternative branch of a lookbehind assertion can match a different length of -string. Perl 5.005 requires them all to have the same length. -

    -

    -(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ meta- -character matches only at the very end of the string. -

    -

    -(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special -meaning is faulted. -

    -

    -(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is -inverted, that is, by default they are not greedy, but if followed by a -question mark they are. -

    -

    -(e) PCRE_ANCHORED can be used to force a pattern to be tried only at the start -of the subject. -

    -

    -(f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options for -pcre_exec() have no Perl equivalents. -

    -

    -(g) The (?R) construct allows for recursive pattern matching (Perl 5.6 can do -this using the (?p{code}) construct, which PCRE cannot of course support.) -

    -
  • REGULAR EXPRESSION DETAILS -

    -The syntax and semantics of the regular expressions supported by PCRE are -described below. Regular expressions are also described in the Perl -documentation and in a number of other books, some of which have copious -examples. Jeffrey Friedl's "Mastering Regular Expressions", published by -O'Reilly (ISBN 1-56592-257), covers them in great detail. -

    -

    -The description here is intended as reference documentation. The basic -operation of PCRE is on strings of bytes. However, there is the beginnings of -some support for UTF-8 character strings. To use this support you must -configure PCRE to include it, and then call pcre_compile() with the -PCRE_UTF8 option. How this affects the pattern matching is described in the -final section of this document. -

    -

    -A regular expression is a pattern that is matched against a subject string from -left to right. Most characters stand for themselves in a pattern, and match the -corresponding characters in the subject. As a trivial example, the pattern -

    -

    -

    -  The quick brown fox
-
    -

    -

    -matches a portion of a subject string that is identical to itself. The power of -regular expressions comes from the ability to include alternatives and -repetitions in the pattern. These are encoded in the pattern by the use of -meta-characters, which do not stand for themselves but instead are -interpreted in some special way. -

    -

    -There are two different sets of meta-characters: those that are recognized -anywhere in the pattern except within square brackets, and those that are -recognized in square brackets. Outside square brackets, the meta-characters are -as follows: -

    -

    -

    -  \      general escape character with several uses
-  ^      assert start of subject (or line, in multiline mode)
-  $      assert end of subject (or line, in multiline mode)
-  .      match any character except newline (by default)
-  [      start character class definition
-  |      start of alternative branch
-  (      start subpattern
-  )      end subpattern
-  ?      extends the meaning of (
-         also 0 or 1 quantifier
-         also quantifier minimizer
-  *      0 or more quantifier
-  +      1 or more quantifier
-  {      start min/max quantifier
-
    -

    -

    -Part of a pattern that is in square brackets is called a "character class". In -a character class the only meta-characters are: -

    -

    -

    -  \      general escape character
-  ^      negate the class, but only if the first character
-  -      indicates character range
-  ]      terminates the character class
-
    -

    -

    -The following sections describe the use of each of the meta-characters. -

    -
  • BACKSLASH -

    -The backslash character has several uses. Firstly, if it is followed by a -non-alphameric character, it takes away any special meaning that character may -have. This use of backslash as an escape character applies both inside and -outside character classes. -

    -

    -For example, if you want to match a "*" character, you write "\*" in the -pattern. This applies whether or not the following character would otherwise be -interpreted as a meta-character, so it is always safe to precede a -non-alphameric with "\" to specify that it stands for itself. In particular, -if you want to match a backslash, you write "\\". -

    -

    -If a pattern is compiled with the PCRE_EXTENDED option, whitespace in the -pattern (other than in a character class) and characters between a "#" outside -a character class and the next newline character are ignored. An escaping -backslash can be used to include a whitespace or "#" character as part of the -pattern. -

    -

    -A second use of backslash provides a way of encoding non-printing characters -in patterns in a visible manner. There is no restriction on the appearance of -non-printing characters, apart from the binary zero that terminates a pattern, -but when a pattern is being prepared by text editing, it is usually easier to -use one of the following escape sequences than the binary character it -represents: -

    -

    -

    -  \a     alarm, that is, the BEL character (hex 07)
-  \cx    "control-x", where x is any character
-  \e     escape (hex 1B)
-  \f     formfeed (hex 0C)
-  \n     newline (hex 0A)
-  \r     carriage return (hex 0D)
-  \t     tab (hex 09)
-  \xhh   character with hex code hh
-  \ddd   character with octal code ddd, or backreference
-
    -

    -

    -The precise effect of "\cx" is as follows: if "x" is a lower case letter, it -is converted to upper case. Then bit 6 of the character (hex 40) is inverted. -Thus "\cz" becomes hex 1A, but "\c{" becomes hex 3B, while "\c;" becomes hex -7B. -

    -

    -After "\x", up to two hexadecimal digits are read (letters can be in upper or -lower case). -

    -

    -After "\0" up to two further octal digits are read. In both cases, if there -are fewer than two digits, just those that are present are used. Thus the -sequence "\0\x\07" specifies two binary zeros followed by a BEL character. -Make sure you supply two digits after the initial zero if the character that -follows is itself an octal digit. -

    -

    -The handling of a backslash followed by a digit other than 0 is complicated. -Outside a character class, PCRE reads it and any following digits as a decimal -number. If the number is less than 10, or if there have been at least that many -previous capturing left parentheses in the expression, the entire sequence is -taken as a back reference. A description of how this works is given -later, following the discussion of parenthesized subpatterns. -

    -

    -Inside a character class, or if the decimal number is greater than 9 and there -have not been that many capturing subpatterns, PCRE re-reads up to three octal -digits following the backslash, and generates a single byte from the least -significant 8 bits of the value. Any subsequent digits stand for themselves. -For example: -

    -

    -

    -  \040   is another way of writing a space
-  \40    is the same, provided there are fewer than 40
-            previous capturing subpatterns
-  \7     is always a back reference
-  \11    might be a back reference, or another way of
-            writing a tab
-  \011   is always a tab
-  \0113  is a tab followed by the character "3"
-  \113   is the character with octal code 113 (since there
-            can be no more than 99 back references)
-  \377   is a byte consisting entirely of 1 bits
-  \81    is either a back reference, or a binary zero
-            followed by the two characters "8" and "1"
-
    -

    -

    -Note that octal values of 100 or greater must not be introduced by a leading -zero, because no more than three octal digits are ever read. -

    -

    -All the sequences that define a single byte value can be used both inside and -outside character classes. In addition, inside a character class, the sequence -"\b" is interpreted as the backspace character (hex 08). Outside a character -class it has a different meaning (see below). -

    -

    -The third use of backslash is for specifying generic character types: -

    -

    -

    -  \d     any decimal digit
-  \D     any character that is not a decimal digit
-  \s     any whitespace character
-  \S     any character that is not a whitespace character
-  \w     any "word" character
-  \W     any "non-word" character
-
    -

    -

    -Each pair of escape sequences partitions the complete set of characters into -two disjoint sets. Any given character matches one, and only one, of each pair. -

    -

    -A "word" character is any letter or digit or the underscore character, that is, -any character which can be part of a Perl "word". The definition of letters and -digits is controlled by PCRE's character tables, and may vary if locale- -specific matching is taking place (see "Locale support" above). For example, in -the "fr" (French) locale, some character codes greater than 128 are used for -accented letters, and these are matched by \w. -

    -

    -These character type sequences can appear both inside and outside character -classes. They each match one character of the appropriate type. If the current -matching point is at the end of the subject string, all of them fail, since -there is no character to match. -

    -

    -The fourth use of backslash is for certain simple assertions. An assertion -specifies a condition that has to be met at a particular point in a match, -without consuming any characters from the subject string. The use of -subpatterns for more complicated assertions is described below. The backslashed -assertions are -

    -

    -

    -  \b     word boundary
-  \B     not a word boundary
-  \A     start of subject (independent of multiline mode)
-  \Z     end of subject or newline at end (independent of multiline mode)
-  \z     end of subject (independent of multiline mode)
-
    -

    -

    -These assertions may not appear in character classes (but note that "\b" has a -different meaning, namely the backspace character, inside a character class). -

    -

    -A word boundary is a position in the subject string where the current character -and the previous character do not both match \w or \W (i.e. one matches -\w and the other matches \W), or the start or end of the string if the -first or last character matches \w, respectively. -

    -

    -The \A, \Z, and \z assertions differ from the traditional circumflex and -dollar (described below) in that they only ever match at the very start and end -of the subject string, whatever options are set. They are not affected by the -PCRE_NOTBOL or PCRE_NOTEOL options. If the startoffset argument of -pcre_exec() is non-zero, \A can never match. The difference between \Z -and \z is that \Z matches before a newline that is the last character of the -string as well as at the end of the string, whereas \z matches only at the -end. -

    -
  • CIRCUMFLEX AND DOLLAR -

    -Outside a character class, in the default matching mode, the circumflex -character is an assertion which is true only if the current matching point is -at the start of the subject string. If the startoffset argument of -pcre_exec() is non-zero, circumflex can never match. Inside a character -class, circumflex has an entirely different meaning (see below). -

    -

    -Circumflex need not be the first character of the pattern if a number of -alternatives are involved, but it should be the first thing in each alternative -in which it appears if the pattern is ever to match that branch. If all -possible alternatives start with a circumflex, that is, if the pattern is -constrained to match only at the start of the subject, it is said to be an -"anchored" pattern. (There are also other constructs that can cause a pattern -to be anchored.) -

    -

    -A dollar character is an assertion which is true only if the current matching -point is at the end of the subject string, or immediately before a newline -character that is the last character in the string (by default). Dollar need -not be the last character of the pattern if a number of alternatives are -involved, but it should be the last item in any branch in which it appears. -Dollar has no special meaning in a character class. -

    -

    -The meaning of dollar can be changed so that it matches only at the very end of -the string, by setting the PCRE_DOLLAR_ENDONLY option at compile or matching -time. This does not affect the \Z assertion. -

    -

    -The meanings of the circumflex and dollar characters are changed if the -PCRE_MULTILINE option is set. When this is the case, they match immediately -after and immediately before an internal "\n" character, respectively, in -addition to matching at the start and end of the subject string. For example, -the pattern /^abc$/ matches the subject string "def\nabc" in multiline mode, -but not otherwise. Consequently, patterns that are anchored in single line mode -because all branches start with "^" are not anchored in multiline mode, and a -match for circumflex is possible when the startoffset argument of -pcre_exec() is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if -PCRE_MULTILINE is set. -

    -

    -Note that the sequences \A, \Z, and \z can be used to match the start and -end of the subject in both modes, and if all branches of a pattern start with -\A it is always anchored, whether PCRE_MULTILINE is set or not. -

    -
  • FULL STOP (PERIOD, DOT) -

    -Outside a character class, a dot in the pattern matches any one character in -the subject, including a non-printing character, but not (by default) newline. -If the PCRE_DOTALL option is set, dots match newlines as well. The handling of -dot is entirely independent of the handling of circumflex and dollar, the only -relationship being that they both involve newline characters. Dot has no -special meaning in a character class. -

    -
  • SQUARE BRACKETS -

    -An opening square bracket introduces a character class, terminated by a closing -square bracket. A closing square bracket on its own is not special. If a -closing square bracket is required as a member of the class, it should be the -first data character in the class (after an initial circumflex, if present) or -escaped with a backslash. -

    -

    -A character class matches a single character in the subject; the character must -be in the set of characters defined by the class, unless the first character in -the class is a circumflex, in which case the subject character must not be in -the set defined by the class. If a circumflex is actually required as a member -of the class, ensure it is not the first character, or escape it with a -backslash. -

    -

    -For example, the character class [aeiou] matches any lower case vowel, while -[^aeiou] matches any character that is not a lower case vowel. Note that a -circumflex is just a convenient notation for specifying the characters which -are in the class by enumerating those that are not. It is not an assertion: it -still consumes a character from the subject string, and fails if the current -pointer is at the end of the string. -

    -

    -When caseless matching is set, any letters in a class represent both their -upper case and lower case versions, so for example, a caseless [aeiou] matches -"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a -caseful version would. -

    -

    -The newline character is never treated in any special way in character classes, -whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE options is. A class -such as [^a] will always match a newline. -

    -

    -The minus (hyphen) character can be used to specify a range of characters in a -character class. For example, [d-m] matches any letter between d and m, -inclusive. If a minus character is required in a class, it must be escaped with -a backslash or appear in a position where it cannot be interpreted as -indicating a range, typically as the first or last character in the class. -

    -

    -It is not possible to have the literal character "]" as the end character of a -range. A pattern such as [W-]46] is interpreted as a class of two characters -("W" and "-") followed by a literal string "46]", so it would match "W46]" or -"-46]". However, if the "]" is escaped with a backslash it is interpreted as -the end of range, so [W-\]46] is interpreted as a single class containing a -range followed by two separate characters. The octal or hexadecimal -representation of "]" can also be used to end a range. -

    -

    -Ranges operate in ASCII collating sequence. They can also be used for -characters specified numerically, for example [\000-\037]. If a range that -includes letters is used when caseless matching is set, it matches the letters -in either case. For example, [W-c] is equivalent to [][\^_`wxyzabc], matched -caselessly, and if character tables for the "fr" locale are in use, -[\xc8-\xcb] matches accented E characters in both cases. -

    -

    -The character types \d, \D, \s, \S, \w, and \W may also appear in a -character class, and add the characters that they match to the class. For -example, [\dABCDEF] matches any hexadecimal digit. A circumflex can -conveniently be used with the upper case character types to specify a more -restricted set of characters than the matching lower case type. For example, -the class [^\W_] matches any letter or digit, but not underscore. -

    -

    -All non-alphameric characters other than \, -, ^ (at the start) and the -terminating ] are non-special in character classes, but it does no harm if they -are escaped. -

    -
  • POSIX CHARACTER CLASSES -

    -Perl 5.6 (not yet released at the time of writing) is going to support the -POSIX notation for character classes, which uses names enclosed by [: and :] -within the enclosing square brackets. PCRE supports this notation. For example, -

    -

    -

    -  [01[:alpha:]%]
-
    -

    -

    -matches "0", "1", any alphabetic character, or "%". The supported class names -are -

    -

    -

    -  alnum    letters and digits
-  alpha    letters
-  ascii    character codes 0 - 127
-  cntrl    control characters
-  digit    decimal digits (same as \d)
-  graph    printing characters, excluding space
-  lower    lower case letters
-  print    printing characters, including space
-  punct    printing characters, excluding letters and digits
-  space    white space (same as \s)
-  upper    upper case letters
-  word     "word" characters (same as \w)
-  xdigit   hexadecimal digits
-
    -

    -

    -The names "ascii" and "word" are Perl extensions. Another Perl extension is -negation, which is indicated by a ^ character after the colon. For example, -

    -

    -

    -  [12[:^digit:]]
-
    -

    -

    -matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the POSIX -syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not -supported, and an error is given if they are encountered. -

    -
  • VERTICAL BAR -

    -Vertical bar characters are used to separate alternative patterns. For example, -the pattern -

    -

    -

    -  gilbert|sullivan
-
    -

    -

    -matches either "gilbert" or "sullivan". Any number of alternatives may appear, -and an empty alternative is permitted (matching the empty string). -The matching process tries each alternative in turn, from left to right, -and the first one that succeeds is used. If the alternatives are within a -subpattern (defined below), "succeeds" means matching the rest of the main -pattern as well as the alternative in the subpattern. -

    -
  • INTERNAL OPTION SETTING -

    -The settings of PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and PCRE_EXTENDED -can be changed from within the pattern by a sequence of Perl option letters -enclosed between "(?" and ")". The option letters are -

    -

    -

    -  i  for PCRE_CASELESS
-  m  for PCRE_MULTILINE
-  s  for PCRE_DOTALL
-  x  for PCRE_EXTENDED
-
    -

    -

    -For example, (?im) sets caseless, multiline matching. It is also possible to -unset these options by preceding the letter with a hyphen, and a combined -setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and -PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also -permitted. If a letter appears both before and after the hyphen, the option is -unset. -

    -

    -The scope of these option changes depends on where in the pattern the setting -occurs. For settings that are outside any subpattern (defined below), the -effect is the same as if the options were set or unset at the start of -matching. The following patterns all behave in exactly the same way: -

    -

    -

    -  (?i)abc
-  a(?i)bc
-  ab(?i)c
-  abc(?i)
-
    -

    -

    -which in turn is the same as compiling the pattern abc with PCRE_CASELESS set. -In other words, such "top level" settings apply to the whole pattern (unless -there are other changes inside subpatterns). If there is more than one setting -of the same option at top level, the rightmost setting is used. -

    -

    -If an option change occurs inside a subpattern, the effect is different. This -is a change of behaviour in Perl 5.005. An option change inside a subpattern -affects only that part of the subpattern that follows it, so -

    -

    -

    -  (a(?i)b)c
-
    -

    -

    -matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used). -By this means, options can be made to have different settings in different -parts of the pattern. Any changes made in one alternative do carry on -into subsequent branches within the same subpattern. For example, -

    -

    -

    -  (a(?i)b|c)
-
    -

    -

    -matches "ab", "aB", "c", and "C", even though when matching "C" the first -branch is abandoned before the option setting. This is because the effects of -option settings happen at compile time. There would be some very weird -behaviour otherwise. -

    -

    -The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed in the -same way as the Perl-compatible options by using the characters U and X -respectively. The (?X) flag setting is special in that it must always occur -earlier in the pattern than any of the additional features it turns on, even -when it is at top level. It is best put at the start. -

    -
  • SUBPATTERNS -

    -Subpatterns are delimited by parentheses (round brackets), which can be nested. -Marking part of a pattern as a subpattern does two things: -

    -

    -1. It localizes a set of alternatives. For example, the pattern -

    -

    -

    -  cat(aract|erpillar|)
-
    -

    -

    -matches one of the words "cat", "cataract", or "caterpillar". Without the -parentheses, it would match "cataract", "erpillar" or the empty string. -

    -

    -2. It sets up the subpattern as a capturing subpattern (as defined above). -When the whole pattern matches, that portion of the subject string that matched -the subpattern is passed back to the caller via the ovector argument of -pcre_exec(). Opening parentheses are counted from left to right (starting -from 1) to obtain the numbers of the capturing subpatterns. -

    -

    -For example, if the string "the red king" is matched against the pattern -

    -

    -

    -  the ((red|white) (king|queen))
-
    -

    -

    -the captured substrings are "red king", "red", and "king", and are numbered 1, -2, and 3, respectively. -

    -

    -The fact that plain parentheses fulfil two functions is not always helpful. -There are often times when a grouping subpattern is required without a -capturing requirement. If an opening parenthesis is followed by "?:", the -subpattern does not do any capturing, and is not counted when computing the -number of any subsequent capturing subpatterns. For example, if the string "the -white queen" is matched against the pattern -

    -

    -

    -  the ((?:red|white) (king|queen))
-
    -

    -

    -the captured substrings are "white queen" and "queen", and are numbered 1 and -2. The maximum number of captured substrings is 99, and the maximum number of -all subpatterns, both capturing and non-capturing, is 200. -

    -

    -As a convenient shorthand, if any option settings are required at the start of -a non-capturing subpattern, the option letters may appear between the "?" and -the ":". Thus the two patterns -

    -

    -

    -  (?i:saturday|sunday)
-  (?:(?i)saturday|sunday)
-
    -

    -

    -match exactly the same set of strings. Because alternative branches are tried -from left to right, and options are not reset until the end of the subpattern -is reached, an option setting in one branch does affect subsequent branches, so -the above patterns match "SUNDAY" as well as "Saturday". -

    -
  • REPETITION -

    -Repetition is specified by quantifiers, which can follow any of the following -items: -

    -

    -

    -  a single character, possibly escaped
-  the . metacharacter
-  a character class
-  a back reference (see next section)
-  a parenthesized subpattern (unless it is an assertion - see below)
-
    -

    -

    -The general repetition quantifier specifies a minimum and maximum number of -permitted matches, by giving the two numbers in curly brackets (braces), -separated by a comma. The numbers must be less than 65536, and the first must -be less than or equal to the second. For example: -

    -

    -

    -  z{2,4}
-
    -

    -

    -matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special -character. If the second number is omitted, but the comma is present, there is -no upper limit; if the second number and the comma are both omitted, the -quantifier specifies an exact number of required matches. Thus -

    -

    -

    -  [aeiou]{3,}
-
    -

    -

    -matches at least 3 successive vowels, but may match many more, while -

    -

    -

    -  \d{8}
-
    -

    -

    -matches exactly 8 digits. An opening curly bracket that appears in a position -where a quantifier is not allowed, or one that does not match the syntax of a -quantifier, is taken as a literal character. For example, {,6} is not a -quantifier, but a literal string of four characters. -

    -

    -The quantifier {0} is permitted, causing the expression to behave as if the -previous item and the quantifier were not present. -

    -

    -For convenience (and historical compatibility) the three most common -quantifiers have single-character abbreviations: -

    -

    -

    -  *    is equivalent to {0,}
-  +    is equivalent to {1,}
-  ?    is equivalent to {0,1}
-
    -

    -

    -It is possible to construct infinite loops by following a subpattern that can -match no characters with a quantifier that has no upper limit, for example: -

    -

    -

    -  (a?)*
-
    -

    -

    -Earlier versions of Perl and PCRE used to give an error at compile time for -such patterns. However, because there are cases where this can be useful, such -patterns are now accepted, but if any repetition of the subpattern does in fact -match no characters, the loop is forcibly broken. -

    -

    -By default, the quantifiers are "greedy", that is, they match as much as -possible (up to the maximum number of permitted times), without causing the -rest of the pattern to fail. The classic example of where this gives problems -is in trying to match comments in C programs. These appear between the -sequences /* and */ and within the sequence, individual * and / characters may -appear. An attempt to match C comments by applying the pattern -

    -

    -

    -  /\*.*\*/
-
    -

    -

    -to the string -

    -

    -

    -  /* first command */  not comment  /* second comment */
-
    -

    -

    -fails, because it matches the entire string owing to the greediness of the .* -item. -

    -

    -However, if a quantifier is followed by a question mark, it ceases to be -greedy, and instead matches the minimum number of times possible, so the -pattern -

    -

    -

    -  /\*.*?\*/
-
    -

    -

    -does the right thing with the C comments. The meaning of the various -quantifiers is not otherwise changed, just the preferred number of matches. -Do not confuse this use of question mark with its use as a quantifier in its -own right. Because it has two uses, it can sometimes appear doubled, as in -

    -

    -

    -  \d??\d
-
    -

    -

    -which matches one digit by preference, but can match two if that is the only -way the rest of the pattern matches. -

    -

    -If the PCRE_UNGREEDY option is set (an option which is not available in Perl), -the quantifiers are not greedy by default, but individual ones can be made -greedy by following them with a question mark. In other words, it inverts the -default behaviour. -

    -

    -When a parenthesized subpattern is quantified with a minimum repeat count that -is greater than 1 or with a limited maximum, more store is required for the -compiled pattern, in proportion to the size of the minimum or maximum. -

    -

    -If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent -to Perl's /s) is set, thus allowing the . to match newlines, the pattern is -implicitly anchored, because whatever follows will be tried against every -character position in the subject string, so there is no point in retrying the -overall match at any position after the first. PCRE treats such a pattern as -though it were preceded by \A. In cases where it is known that the subject -string contains no newlines, it is worth setting PCRE_DOTALL when the pattern -begins with .* in order to obtain this optimization, or alternatively using ^ -to indicate anchoring explicitly. -

    -

    -When a capturing subpattern is repeated, the value captured is the substring -that matched the final iteration. For example, after -

    -

    -

    -  (tweedle[dume]{3}\s*)+
-
    -

    -

    -has matched "tweedledum tweedledee" the value of the captured substring is -"tweedledee". However, if there are nested capturing subpatterns, the -corresponding captured values may have been set in previous iterations. For -example, after -

    -

    -

    -  /(a|(b))+/
-
    -

    -

    -matches "aba" the value of the second captured substring is "b". -

    -
  • BACK REFERENCES -

    -Outside a character class, a backslash followed by a digit greater than 0 (and -possibly further digits) is a back reference to a capturing subpattern earlier -(i.e. to its left) in the pattern, provided there have been that many previous -capturing left parentheses. -

    -

    -However, if the decimal number following the backslash is less than 10, it is -always taken as a back reference, and causes an error only if there are not -that many capturing left parentheses in the entire pattern. In other words, the -parentheses that are referenced need not be to the left of the reference for -numbers less than 10. See the section entitled "Backslash" above for further -details of the handling of digits following a backslash. -

    -

    -A back reference matches whatever actually matched the capturing subpattern in -the current subject string, rather than anything matching the subpattern -itself. So the pattern -

    -

    -

    -  (sens|respons)e and \1ibility
-
    -

    -

    -matches "sense and sensibility" and "response and responsibility", but not -"sense and responsibility". If caseful matching is in force at the time of the -back reference, the case of letters is relevant. For example, -

    -

    -

    -  ((?i)rah)\s+\1
-
    -

    -

    -matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original -capturing subpattern is matched caselessly. -

    -

    -There may be more than one back reference to the same subpattern. If a -subpattern has not actually been used in a particular match, any back -references to it always fail. For example, the pattern -

    -

    -

    -  (a|(bc))\2
-
    -

    -

    -always fails if it starts to match "a" rather than "bc". Because there may be -up to 99 back references, all digits following the backslash are taken -as part of a potential back reference number. If the pattern continues with a -digit character, some delimiter must be used to terminate the back reference. -If the PCRE_EXTENDED option is set, this can be whitespace. Otherwise an empty -comment can be used. -

    -

    -A back reference that occurs inside the parentheses to which it refers fails -when the subpattern is first used, so, for example, (a\1) never matches. -However, such references can be useful inside repeated subpatterns. For -example, the pattern -

    -

    -

    -  (a|b\1)+
-
    -

    -

    -matches any number of "a"s and also "aba", "ababbaa" etc. At each iteration of -the subpattern, the back reference matches the character string corresponding -to the previous iteration. In order for this to work, the pattern must be such -that the first iteration does not need to match the back reference. This can be -done using alternation, as in the example above, or by a quantifier with a -minimum of zero. -

    -
  • ASSERTIONS -

    -An assertion is a test on the characters following or preceding the current -matching point that does not actually consume any characters. The simple -assertions coded as \b, \B, \A, \Z, \z, ^ and $ are described above. More -complicated assertions are coded as subpatterns. There are two kinds: those -that look ahead of the current position in the subject string, and those that -look behind it. -

    -

    -An assertion subpattern is matched in the normal way, except that it does not -cause the current matching position to be changed. Lookahead assertions start -with (?= for positive assertions and (?! for negative assertions. For example, -

    -

    -

    -  \w+(?=;)
-
    -

    -

    -matches a word followed by a semicolon, but does not include the semicolon in -the match, and -

    -

    -

    -  foo(?!bar)
-
    -

    -

    -matches any occurrence of "foo" that is not followed by "bar". Note that the -apparently similar pattern -

    -

    -

    -  (?!foo)bar
-
    -

    -

    -does not find an occurrence of "bar" that is preceded by something other than -"foo"; it finds any occurrence of "bar" whatsoever, because the assertion -(?!foo) is always true when the next three characters are "bar". A -lookbehind assertion is needed to achieve this effect. -

    -

    -Lookbehind assertions start with (?<= for positive assertions and (?<! for -negative assertions. For example, -

    -

    -

    -  (?<!foo)bar
-
    -

    -

    -does find an occurrence of "bar" that is not preceded by "foo". The contents of -a lookbehind assertion are restricted such that all the strings it matches must -have a fixed length. However, if there are several alternatives, they do not -all have to have the same fixed length. Thus -

    -

    -

    -  (?<=bullock|donkey)
-
    -

    -

    -is permitted, but -

    -

    -

    -  (?<!dogs?|cats?)
-
    -

    -

    -causes an error at compile time. Branches that match different length strings -are permitted only at the top level of a lookbehind assertion. This is an -extension compared with Perl 5.005, which requires all branches to match the -same length of string. An assertion such as -

    -

    -

    -  (?<=ab(c|de))
-
    -

    -

    -is not permitted, because its single top-level branch can match two different -lengths, but it is acceptable if rewritten to use two top-level branches: -

    -

    -

    -  (?<=abc|abde)
-
    -

    -

    -The implementation of lookbehind assertions is, for each alternative, to -temporarily move the current position back by the fixed width and then try to -match. If there are insufficient characters before the current position, the -match is deemed to fail. Lookbehinds in conjunction with once-only subpatterns -can be particularly useful for matching at the ends of strings; an example is -given at the end of the section on once-only subpatterns. -

    -

    -Several assertions (of any sort) may occur in succession. For example, -

    -

    -

    -  (?<=\d{3})(?<!999)foo
-
    -

    -

    -matches "foo" preceded by three digits that are not "999". Notice that each of -the assertions is applied independently at the same point in the subject -string. First there is a check that the previous three characters are all -digits, and then there is a check that the same three characters are not "999". -This pattern does not match "foo" preceded by six characters, the first -of which are digits and the last three of which are not "999". For example, it -doesn't match "123abcfoo". A pattern to do that is -

    -

    -

    -  (?<=\d{3}...)(?<!999)foo
-
    -

    -

    -This time the first assertion looks at the preceding six characters, checking -that the first three are digits, and then the second assertion checks that the -preceding three characters are not "999". -

    -

    -Assertions can be nested in any combination. For example, -

    -

    -

    -  (?<=(?<!foo)bar)baz
-
    -

    -

    -matches an occurrence of "baz" that is preceded by "bar" which in turn is not -preceded by "foo", while -

    -

    -

    -  (?<=\d{3}(?!999)...)foo
-
    -

    -

    -is another pattern which matches "foo" preceded by three digits and any three -characters that are not "999". -

    -

    -Assertion subpatterns are not capturing subpatterns, and may not be repeated, -because it makes no sense to assert the same thing several times. If any kind -of assertion contains capturing subpatterns within it, these are counted for -the purposes of numbering the capturing subpatterns in the whole pattern. -However, substring capturing is carried out only for positive assertions, -because it does not make sense for negative assertions. -

    -

    -Assertions count towards the maximum of 200 parenthesized subpatterns. -

    -
  • ONCE-ONLY SUBPATTERNS -

    -With both maximizing and minimizing repetition, failure of what follows -normally causes the repeated item to be re-evaluated to see if a different -number of repeats allows the rest of the pattern to match. Sometimes it is -useful to prevent this, either to change the nature of the match, or to cause -it fail earlier than it otherwise might, when the author of the pattern knows -there is no point in carrying on. -

    -

    -Consider, for example, the pattern \d+foo when applied to the subject line -

    -

    -

    -  123456bar
-
    -

    -

    -After matching all 6 digits and then failing to match "foo", the normal -action of the matcher is to try again with only 5 digits matching the \d+ -item, and then with 4, and so on, before ultimately failing. Once-only -subpatterns provide the means for specifying that once a portion of the pattern -has matched, it is not to be re-evaluated in this way, so the matcher would -give up immediately on failing to match "foo" the first time. The notation is -another kind of special parenthesis, starting with (?> as in this example: -

    -

    -

    -  (?>\d+)bar
-
    -

    -

    -This kind of parenthesis "locks up" the part of the pattern it contains once -it has matched, and a failure further into the pattern is prevented from -backtracking into it. Backtracking past it to previous items, however, works as -normal. -

    -

    -An alternative description is that a subpattern of this type matches the string -of characters that an identical standalone pattern would match, if anchored at -the current point in the subject string. -

    -

    -Once-only subpatterns are not capturing subpatterns. Simple cases such as the -above example can be thought of as a maximizing repeat that must swallow -everything it can. So, while both \d+ and \d+? are prepared to adjust the -number of digits they match in order to make the rest of the pattern match, -(?>\d+) can only match an entire sequence of digits. -

    -

    -This construction can of course contain arbitrarily complicated subpatterns, -and it can be nested. -

    -

    -Once-only subpatterns can be used in conjunction with lookbehind assertions to -specify efficient matching at the end of the subject string. Consider a simple -pattern such as -

    -

    -

    -  abcd$
-
    -

    -

    -when applied to a long string which does not match. Because matching proceeds -from left to right, PCRE will look for each "a" in the subject and then see if -what follows matches the rest of the pattern. If the pattern is specified as -

    -

    -

    -  ^.*abcd$
-
    -

    -

    -the initial .* matches the entire string at first, but when this fails (because -there is no following "a"), it backtracks to match all but the last character, -then all but the last two characters, and so on. Once again the search for "a" -covers the entire string, from right to left, so we are no better off. However, -if the pattern is written as -

    -

    -

    -  ^(?>.*)(?<=abcd)
-
    -

    -

    -there can be no backtracking for the .* item; it can match only the entire -string. The subsequent lookbehind assertion does a single test on the last four -characters. If it fails, the match fails immediately. For long strings, this -approach makes a significant difference to the processing time. -

    -

    -When a pattern contains an unlimited repeat inside a subpattern that can itself -be repeated an unlimited number of times, the use of a once-only subpattern is -the only way to avoid some failing matches taking a very long time indeed. -The pattern -

    -

    -

    -  (\D+|<\d+>)*[!?]
-
    -

    -

    -matches an unlimited number of substrings that either consist of non-digits, or -digits enclosed in <>, followed by either ! or ?. When it matches, it runs -quickly. However, if it is applied to -

    -

    -

    -  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-
    -

    -

    -it takes a long time before reporting failure. This is because the string can -be divided between the two repeats in a large number of ways, and all have to -be tried. (The example used [!?] rather than a single character at the end, -because both PCRE and Perl have an optimization that allows for fast failure -when a single character is used. They remember the last single character that -is required for a match, and fail early if it is not present in the string.) -If the pattern is changed to -

    -

    -

    -  ((?>\D+)|<\d+>)*[!?]
-
    -

    -

    -sequences of non-digits cannot be broken, and failure happens quickly. -

    -
  • CONDITIONAL SUBPATTERNS -

    -It is possible to cause the matching process to obey a subpattern -conditionally or to choose between two alternative subpatterns, depending on -the result of an assertion, or whether a previous capturing subpattern matched -or not. The two possible forms of conditional subpattern are -

    -

    -

    -  (?(condition)yes-pattern)
-  (?(condition)yes-pattern|no-pattern)
-
    -

    -

    -If the condition is satisfied, the yes-pattern is used; otherwise the -no-pattern (if present) is used. If there are more than two alternatives in the -subpattern, a compile-time error occurs. -

    -

    -There are two kinds of condition. If the text between the parentheses consists -of a sequence of digits, the condition is satisfied if the capturing subpattern -of that number has previously matched. The number must be greater than zero. -Consider the following pattern, which contains non-significant white space to -make it more readable (assume the PCRE_EXTENDED option) and to divide it into -three parts for ease of discussion: -

    -

    -

    -  ( \( )?    [^()]+    (?(1) \) )
-
    -

    -

    -The first part matches an optional opening parenthesis, and if that -character is present, sets it as the first captured substring. The second part -matches one or more characters that are not parentheses. The third part is a -conditional subpattern that tests whether the first set of parentheses matched -or not. If they did, that is, if subject started with an opening parenthesis, -the condition is true, and so the yes-pattern is executed and a closing -parenthesis is required. Otherwise, since no-pattern is not present, the -subpattern matches nothing. In other words, this pattern matches a sequence of -non-parentheses, optionally enclosed in parentheses. -

    -

    -If the condition is not a sequence of digits, it must be an assertion. This may -be a positive or negative lookahead or lookbehind assertion. Consider this -pattern, again containing non-significant white space, and with the two -alternatives on the second line: -

    -

    -

    -  (?(?=[^a-z]*[a-z])
-  \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
-
    -

    -

    -The condition is a positive lookahead assertion that matches an optional -sequence of non-letters followed by a letter. In other words, it tests for the -presence of at least one letter in the subject. If a letter is found, the -subject is matched against the first alternative; otherwise it is matched -against the second. This pattern matches strings in one of the two forms -dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits. -

    -
  • COMMENTS -

    -The sequence (?# marks the start of a comment which continues up to the next -closing parenthesis. Nested parentheses are not permitted. The characters -that make up a comment play no part in the pattern matching at all. -

    -

    -If the PCRE_EXTENDED option is set, an unescaped # character outside a -character class introduces a comment that continues up to the next newline -character in the pattern. -

    -
  • RECURSIVE PATTERNS -

    -Consider the problem of matching a string in parentheses, allowing for -unlimited nested parentheses. Without the use of recursion, the best that can -be done is to use a pattern that matches up to some fixed depth of nesting. It -is not possible to handle an arbitrary nesting depth. Perl 5.6 has provided an -experimental facility that allows regular expressions to recurse (amongst other -things). It does this by interpolating Perl code in the expression at run time, -and the code can refer to the expression itself. A Perl pattern to solve the -parentheses problem can be created like this: -

    -

    -

    -  $re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
-
    -

    -

    -The (?p{...}) item interpolates Perl code at run time, and in this case refers -recursively to the pattern in which it appears. Obviously, PCRE cannot support -the interpolation of Perl code. Instead, the special item (?R) is provided for -the specific case of recursion. This PCRE pattern solves the parentheses -problem (assume the PCRE_EXTENDED option is set so that white space is -ignored): -

    -

    -

    -  \( ( (?>[^()]+) | (?R) )* \)
-
    -

    -

    -First it matches an opening parenthesis. Then it matches any number of -substrings which can either be a sequence of non-parentheses, or a recursive -match of the pattern itself (i.e. a correctly parenthesized substring). Finally -there is a closing parenthesis. -

    -

    -This particular example pattern contains nested unlimited repeats, and so the -use of a once-only subpattern for matching strings of non-parentheses is -important when applying the pattern to strings that do not match. For example, -when it is applied to -

    -

    -

    -  (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
-
    -

    -

    -it yields "no match" quickly. However, if a once-only subpattern is not used, -the match runs for a very long time indeed because there are so many different -ways the + and * repeats can carve up the subject, and all have to be tested -before failure can be reported. -

    -

    -The values set for any capturing subpatterns are those from the outermost level -of the recursion at which the subpattern value is set. If the pattern above is -matched against -

    -

    -

    -  (ab(cd)ef)
-
    -

    -

    -the value for the capturing parentheses is "ef", which is the last value taken -on at the top level. If additional parentheses are added, giving -

    -

    -

    -  \( ( ( (?>[^()]+) | (?R) )* ) \)
-     ^                        ^
-     ^                        ^
-
    -the string they capture is "ab(cd)ef", the contents of the top level -parentheses. If there are more than 15 capturing parentheses in a pattern, PCRE -has to obtain extra memory to store data during a recursion, which it does by -using pcre_malloc, freeing it via pcre_free afterwards. If no -memory can be obtained, it saves data for the first 15 capturing parentheses -only, as there is no way to give an out-of-memory error from within a -recursion. -

    -
  • PERFORMANCE -

    -Certain items that may appear in patterns are more efficient than others. It is -more efficient to use a character class like [aeiou] than a set of alternatives -such as (a|e|i|o|u). In general, the simplest construction that provides the -required behaviour is usually the most efficient. Jeffrey Friedl's book -contains a lot of discussion about optimizing regular expressions for efficient -performance. -

    -

    -When a pattern begins with .* and the PCRE_DOTALL option is set, the pattern is -implicitly anchored by PCRE, since it can match only at the start of a subject -string. However, if PCRE_DOTALL is not set, PCRE cannot make this optimization, -because the . metacharacter does not then match a newline, and if the subject -string contains newlines, the pattern may match from the character immediately -following one of them instead of from the very start. For example, the pattern -

    -

    -

    -  (.*) second
-
    -

    -

    -matches the subject "first\nand second" (where \n stands for a newline -character) with the first captured substring being "and". In order to do this, -PCRE has to retry the match starting after every newline in the subject. -

    -

    -If you are using such a pattern with subject strings that do not contain -newlines, the best performance is obtained by setting PCRE_DOTALL, or starting -the pattern with ^.* to indicate explicit anchoring. That saves PCRE from -having to scan along the subject looking for a newline to restart at. -

    -

    -Beware of patterns that contain nested indefinite repeats. These can take a -long time to run when applied to a string that does not match. Consider the -pattern fragment -

    -

    -

    -  (a+)*
-
    -

    -

    -This can match "aaaa" in 33 different ways, and this number increases very -rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4 -times, and for each of those cases other than 0, the + repeats can match -different numbers of times.) When the remainder of the pattern is such that the -entire match is going to fail, PCRE has in principle to try every possible -variation, and this can take an extremely long time. -

    -

    -An optimization catches some of the more simple cases such as -

    -

    -

    -  (a+)*b
-
    -

    -

    -where a literal character follows. Before embarking on the standard matching -procedure, PCRE checks that there is a "b" later in the subject string, and if -there is not, it fails the match immediately. However, when there is no -following literal this optimization cannot be used. You can see the difference -by comparing the behaviour of -

    -

    -

    -  (a+)*\d
-
    -

    -

    -with the pattern above. The former gives a failure almost instantly when -applied to a whole line of "a" characters, whereas the latter takes an -appreciable time with strings longer than about 20 characters. -

    -
  • UTF-8 SUPPORT -

    -Starting at release 3.3, PCRE has some support for character strings encoded -in the UTF-8 format. This is incomplete, and is regarded as experimental. In -order to use it, you must configure PCRE to include UTF-8 support in the code, -and, in addition, you must call pcre_compile() with the PCRE_UTF8 option -flag. When you do this, both the pattern and any subject strings that are -matched against it are treated as UTF-8 strings instead of just strings of -bytes, but only in the cases that are mentioned below. -

    -

    -If you compile PCRE with UTF-8 support, but do not use it at run time, the -library will be a bit bigger, but the additional run time overhead is limited -to testing the PCRE_UTF8 flag in several places, so should not be very large. -

    -

    -PCRE assumes that the strings it is given contain valid UTF-8 codes. It does -not diagnose invalid UTF-8 strings. If you pass invalid UTF-8 strings to PCRE, -the results are undefined. -

    -

    -Running with PCRE_UTF8 set causes these changes in the way PCRE works: -

    -

    -1. In a pattern, the escape sequence \x{...}, where the contents of the braces -is a string of hexadecimal digits, is interpreted as a UTF-8 character whose -code number is the given hexadecimal number, for example: \x{1234}. This -inserts from one to six literal bytes into the pattern, using the UTF-8 -encoding. If a non-hexadecimal digit appears between the braces, the item is -not recognized. -

    -

    -2. The original hexadecimal escape sequence, \xhh, generates a two-byte UTF-8 -character if its value is greater than 127. -

    -

    -3. Repeat quantifiers are NOT correctly handled if they follow a multibyte -character. For example, \x{100}* and \xc3+ do not work. If you want to -repeat such characters, you must enclose them in non-capturing parentheses, -for example (?:\x{100}), at present. -

    -

    -4. The dot metacharacter matches one UTF-8 character instead of a single byte. -

    -

    -5. Unlike literal UTF-8 characters, the dot metacharacter followed by a -repeat quantifier does operate correctly on UTF-8 characters instead of -single bytes. -

    -

    -4. Although the \x{...} escape is permitted in a character class, characters -whose values are greater than 255 cannot be included in a class. -

    -

    -5. A class is matched against a UTF-8 character instead of just a single byte, -but it can match only characters whose values are less than 256. Characters -with greater values always fail to match a class. -

    -

    -6. Repeated classes work correctly on multiple characters. -

    -

    -7. Classes containing just a single character whose value is greater than 127 -(but less than 256), for example, [\x80] or [^\x{93}], do not work because -these are optimized into single byte matches. In the first case, of course, -the class brackets are just redundant. -

    -

    -8. Lookbehind assertions move backwards in the subject by a fixed number of -characters instead of a fixed number of bytes. Simple cases have been tested -to work correctly, but there may be hidden gotchas herein. -

    -

    -9. The character types such as \d and \w do not work correctly with UTF-8 -characters. They continue to test a single byte. -

    -

    -10. Anything not explicitly mentioned here continues to work in bytes rather -than in characters. -

    -

    -The following UTF-8 features of Perl 5.6 are not implemented: -

    -

    -1. The escape sequence \C to match a single byte. -

    -

    -2. The use of Unicode tables and properties and escapes \p, \P, and \X. -

    -
  • SAMPLE PROGRAM -

    -The code below is a simple, complete demonstration program, to get you started -with using PCRE. This code is also supplied in the file pcredemo.c in the -PCRE distribution. -

    -

    -The program compiles the regular expression that is its first argument, and -matches it against the subject string in its second argument. No options are -set, and default character tables are used. If matching succeeds, the program -outputs the portion of the subject that matched, together with the contents of -any captured substrings. -

    -

    -On a Unix system that has PCRE installed in /usr/local, you can compile -the demonstration program using a command like this: -

    -

    -

    -  gcc -o pcredemo pcredemo.c -I/usr/local/include -L/usr/local/lib -lpcre
-
    -

    -

    -Then you can run simple tests like this: -

    -

    -

    -  ./pcredemo 'cat|dog' 'the cat sat on the mat'
-
    -

    -

    -Note that there is a much more comprehensive test program, called -pcretest, which supports many more facilities for testing regular -expressions. The pcredemo program is provided as a simple coding example. -

    -

    -On some operating systems (e.g. Solaris) you may get an error like this when -you try to run pcredemo: -

    -

    -

    -  ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
-
    -

    -

    -This is caused by the way shared library support works on those systems. You -need to add -

    -

    -

    -  -R/usr/local/lib
-
    -

    -

    -to the compile command to get round this problem. Here's the code: -

    -

    -

    -  #include <stdio.h>
-  #include <string.h>
-  #include <pcre.h>
-
    -

    -

    -

    -  #define OVECCOUNT 30    /* should be a multiple of 3 */
-
    -

    -

    -

    -  int main(int argc, char **argv)
-  {
-  pcre *re;
-  const char *error;
-  int erroffset;
-  int ovector[OVECCOUNT];
-  int rc, i;
-
    -

    -

    -

    -  if (argc != 3)
-    {
-    printf("Two arguments required: a regex and a "
-      "subject string\n");
-    return 1;
-    }
-
    -

    -

    -

    -  /* Compile the regular expression in the first argument */
-
    -

    -

    -

    -  re = pcre_compile(
-    argv[1],     /* the pattern */
-    0,           /* default options */
-    &error,      /* for error message */
-    &erroffset,  /* for error offset */
-    NULL);       /* use default character tables */
-
    -

    -

    -

    -  /* Compilation failed: print the error message and exit */
-
    -

    -

    -

    -  if (re == NULL)
-    {
-    printf("PCRE compilation failed at offset %d: %s\n",
-      erroffset, error);
-    return 1;
-    }
-
    -

    -

    -

    -  /* Compilation succeeded: match the subject in the second
-     argument */
-
    -

    -

    -

    -  rc = pcre_exec(
-    re,          /* the compiled pattern */
-    NULL,        /* we didn't study the pattern */
-    argv[2],     /* the subject string */
-    (int)strlen(argv[2]), /* the length of the subject */
-    0,           /* start at offset 0 in the subject */
-    0,           /* default options */
-    ovector,     /* vector for substring information */
-    OVECCOUNT);  /* number of elements in the vector */
-
    -

    -

    -

    -  /* Matching failed: handle error cases */
-
    -

    -

    -

    -  if (rc < 0)
-    {
-    switch(rc)
-      {
-      case PCRE_ERROR_NOMATCH: printf("No match\n"); break;
-      /*
-      Handle other special cases if you like
-      */
-      default: printf("Matching error %d\n", rc); break;
-      }
-    return 1;
-    }
-
    -

    -

    -

    -  /* Match succeded */
-
    -

    -

    -

    -  printf("Match succeeded\n");
-
    -

    -

    -

    -  /* The output vector wasn't big enough */
-
    -

    -

    -

    -  if (rc == 0)
-    {
-    rc = OVECCOUNT/3;
-    printf("ovector only has room for %d captured "
-      substrings\n", rc - 1);
-    }
-
    -

    -

    -

    -  /* Show substrings stored in the output vector */
-
    -

    -

    -

    -  for (i = 0; i < rc; i++)
-    {
-    char *substring_start = argv[2] + ovector[2*i];
-    int substring_length = ovector[2*i+1] - ovector[2*i];
-    printf("%2d: %.*s\n", i, substring_length,
-      substring_start);
-    }
-
    -

    -

    -

    -  return 0;
-  }
-
    -

    -
  • AUTHOR -

    -Philip Hazel <ph10@cam.ac.uk> -
    -University Computing Service, -
    -New Museums Site, -
    -Cambridge CB2 3QG, England. -
    -Phone: +44 1223 334714 -

    -

    -Last updated: 15 August 2001 -
    -Copyright (c) 1997-2001 University of Cambridge. diff --git a/srclib/pcre/doc/pcre.txt b/srclib/pcre/doc/pcre.txt deleted file mode 100644 index fdf0d6ff67..0000000000 --- a/srclib/pcre/doc/pcre.txt +++ /dev/null @@ -1,3769 +0,0 @@ ------------------------------------------------------------------------------ -This file contains a concatenation of the PCRE man pages, converted to plain -text format for ease of searching with a text editor, or for use on systems -that do not have a man page processor. The small individual files that give -synopses of each function in the library have not been included. There are -separate text files for the pcregrep and pcretest commands. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -INTRODUCTION - - The PCRE library is a set of functions that implement regular expres- - sion pattern matching using the same syntax and semantics as Perl, with - just a few differences. The current implementation of PCRE (release - 5.x) corresponds approximately with Perl 5.8, including support for - UTF-8 encoded strings and Unicode general category properties. However, - this support has to be explicitly enabled; it is not the default. - - PCRE is written in C and released as a C library. A number of people - have written wrappers and interfaces of various kinds. A C++ class is - included in these contributions, which can be found in the Contrib - directory at the primary FTP site, which is: - - ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre - - Details of exactly which Perl regular expression features are and are - not supported by PCRE are given in separate documents. See the pcrepat- - tern and pcrecompat pages. - - Some features of PCRE can be included, excluded, or changed when the - library is built. The pcre_config() function makes it possible for a - client to discover which features are available. The features them- - selves are described in the pcrebuild page. Documentation about build- - ing PCRE for various operating systems can be found in the README file - in the source distribution. - - -USER DOCUMENTATION - - The user documentation for PCRE comprises a number of different sec- - tions. In the "man" format, each of these is a separate "man page". In - the HTML format, each is a separate page, linked from the index page. - In the plain text format, all the sections are concatenated, for ease - of searching. The sections are as follows: - - pcre this document - pcreapi details of PCRE's native API - pcrebuild options for building PCRE - pcrecallout details of the callout feature - pcrecompat discussion of Perl compatibility - pcregrep description of the pcregrep command - pcrepartial details of the partial matching facility - pcrepattern syntax and semantics of supported - regular expressions - pcreperform discussion of performance issues - pcreposix the POSIX-compatible API - pcreprecompile details of saving and re-using precompiled patterns - pcresample discussion of the sample program - pcretest description of the pcretest testing command - - In addition, in the "man" and HTML formats, there is a short page for - each library function, listing its arguments and results. - - -LIMITATIONS - - There are some size limitations in PCRE but it is hoped that they will - never in practice be relevant. - - The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE - is compiled with the default internal linkage size of 2. If you want to - process regular expressions that are truly enormous, you can compile - PCRE with an internal linkage size of 3 or 4 (see the README file in - the source distribution and the pcrebuild documentation for details). - In these cases the limit is substantially larger. However, the speed - of execution will be slower. - - All values in repeating quantifiers must be less than 65536. The maxi- - mum number of capturing subpatterns is 65535. - - There is no limit to the number of non-capturing subpatterns, but the - maximum depth of nesting of all kinds of parenthesized subpattern, - including capturing subpatterns, assertions, and other types of subpat- - tern, is 200. - - The maximum length of a subject string is the largest positive number - that an integer variable can hold. However, PCRE uses recursion to han- - dle subpatterns and indefinite repetition. This means that the avail- - able stack space may limit the size of a subject string that can be - processed by certain patterns. - - -UTF-8 AND UNICODE PROPERTY SUPPORT - - From release 3.3, PCRE has had some support for character strings - encoded in the UTF-8 format. For release 4.0 this was greatly extended - to cover most common requirements, and in release 5.0 additional sup- - port for Unicode general category properties was added. - - In order process UTF-8 strings, you must build PCRE to include UTF-8 - support in the code, and, in addition, you must call pcre_compile() - with the PCRE_UTF8 option flag. When you do this, both the pattern and - any subject strings that are matched against it are treated as UTF-8 - strings instead of just strings of bytes. - - If you compile PCRE with UTF-8 support, but do not use it at run time, - the library will be a bit bigger, but the additional run time overhead - is limited to testing the PCRE_UTF8 flag in several places, so should - not be very large. - - If PCRE is built with Unicode character property support (which implies - UTF-8 support), the escape sequences \p{..}, \P{..}, and \X are sup- - ported. The available properties that can be tested are limited to the - general category properties such as Lu for an upper case letter or Nd - for a decimal number. A full list is given in the pcrepattern documen- - tation. The PCRE library is increased in size by about 90K when Unicode - property support is included. - - The following comments apply when PCRE is running in UTF-8 mode: - - 1. When you set the PCRE_UTF8 flag, the strings passed as patterns and - subjects are checked for validity on entry to the relevant functions. - If an invalid UTF-8 string is passed, an error return is given. In some - situations, you may already know that your strings are valid, and - therefore want to skip these checks in order to improve performance. If - you set the PCRE_NO_UTF8_CHECK flag at compile time or at run time, - PCRE assumes that the pattern or subject it is given (respectively) - contains only valid UTF-8 codes. In this case, it does not diagnose an - invalid UTF-8 string. If you pass an invalid UTF-8 string to PCRE when - PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program may - crash. - - 2. In a pattern, the escape sequence \x{...}, where the contents of the - braces is a string of hexadecimal digits, is interpreted as a UTF-8 - character whose code number is the given hexadecimal number, for exam- - ple: \x{1234}. If a non-hexadecimal digit appears between the braces, - the item is not recognized. This escape sequence can be used either as - a literal, or within a character class. - - 3. The original hexadecimal escape sequence, \xhh, matches a two-byte - UTF-8 character if the value is greater than 127. - - 4. Repeat quantifiers apply to complete UTF-8 characters, not to indi- - vidual bytes, for example: \x{100}{3}. - - 5. The dot metacharacter matches one UTF-8 character instead of a sin- - gle byte. - - 6. The escape sequence \C can be used to match a single byte in UTF-8 - mode, but its use can lead to some strange effects. - - 7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly - test characters of any code value, but the characters that PCRE recog- - nizes as digits, spaces, or word characters remain the same set as - before, all with values less than 256. This remains true even when PCRE - includes Unicode property support, because to do otherwise would slow - down PCRE in many common cases. If you really want to test for a wider - sense of, say, "digit", you must use Unicode property tests such as - \p{Nd}. - - 8. Similarly, characters that match the POSIX named character classes - are all low-valued characters. - - 9. Case-insensitive matching applies only to characters whose values - are less than 128, unless PCRE is built with Unicode property support. - Even when Unicode property support is available, PCRE still uses its - own character tables when checking the case of low-valued characters, - so as not to degrade performance. The Unicode property information is - used only for characters with higher values. - - -AUTHOR - - Philip Hazel - University Computing Service, - Cambridge CB2 3QG, England. - Phone: +44 1223 334714 - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PCRE BUILD-TIME OPTIONS - - This document describes the optional features of PCRE that can be - selected when the library is compiled. They are all selected, or dese- - lected, by providing options to the configure script that is run before - the make command. The complete list of options for configure (which - includes the standard ones such as the selection of the installation - directory) can be obtained by running - - ./configure --help - - The following sections describe certain options whose names begin with - --enable or --disable. These settings specify changes to the defaults - for the configure command. Because of the way that configure works, - --enable and --disable always come in pairs, so the complementary - option always exists as well, but as it specifies the default, it is - not described. - - -UTF-8 SUPPORT - - To build PCRE with support for UTF-8 character strings, add - - --enable-utf8 - - to the configure command. Of itself, this does not make PCRE treat - strings as UTF-8. As well as compiling PCRE with this option, you also - have have to set the PCRE_UTF8 option when you call the pcre_compile() - function. - - -UNICODE CHARACTER PROPERTY SUPPORT - - UTF-8 support allows PCRE to process character values greater than 255 - in the strings that it handles. On its own, however, it does not pro- - vide any facilities for accessing the properties of such characters. If - you want to be able to use the pattern escapes \P, \p, and \X, which - refer to Unicode character properties, you must add - - --enable-unicode-properties - - to the configure command. This implies UTF-8 support, even if you have - not explicitly requested it. - - Including Unicode property support adds around 90K of tables to the - PCRE library, approximately doubling its size. Only the general cate- - gory properties such as Lu and Nd are supported. Details are given in - the pcrepattern documentation. - - -CODE VALUE OF NEWLINE - - By default, PCRE treats character 10 (linefeed) as the newline charac- - ter. This is the normal newline character on Unix-like systems. You can - compile PCRE to use character 13 (carriage return) instead by adding - - --enable-newline-is-cr - - to the configure command. For completeness there is also a --enable- - newline-is-lf option, which explicitly specifies linefeed as the new- - line character. - - -BUILDING SHARED AND STATIC LIBRARIES - - The PCRE building process uses libtool to build both shared and static - Unix libraries by default. You can suppress one of these by adding one - of - - --disable-shared - --disable-static - - to the configure command, as required. - - -POSIX MALLOC USAGE - - When PCRE is called through the POSIX interface (see the pcreposix doc- - umentation), additional working storage is required for holding the - pointers to capturing substrings, because PCRE requires three integers - per substring, whereas the POSIX interface provides only two. If the - number of expected substrings is small, the wrapper function uses space - on the stack, because this is faster than using malloc() for each call. - The default threshold above which the stack is no longer used is 10; it - can be changed by adding a setting such as - - --with-posix-malloc-threshold=20 - - to the configure command. - - -LIMITING PCRE RESOURCE USAGE - - Internally, PCRE has a function called match(), which it calls repeat- - edly (possibly recursively) when matching a pattern. By controlling the - maximum number of times this function may be called during a single - matching operation, a limit can be placed on the resources used by a - single call to pcre_exec(). The limit can be changed at run time, as - described in the pcreapi documentation. The default is 10 million, but - this can be changed by adding a setting such as - - --with-match-limit=500000 - - to the configure command. - - -HANDLING VERY LARGE PATTERNS - - Within a compiled pattern, offset values are used to point from one - part to another (for example, from an opening parenthesis to an alter- - nation metacharacter). By default, two-byte values are used for these - offsets, leading to a maximum size for a compiled pattern of around - 64K. This is sufficient to handle all but the most gigantic patterns. - Nevertheless, some people do want to process enormous patterns, so it - is possible to compile PCRE to use three-byte or four-byte offsets by - adding a setting such as - - --with-link-size=3 - - to the configure command. The value given must be 2, 3, or 4. Using - longer offsets slows down the operation of PCRE because it has to load - additional bytes when handling them. - - If you build PCRE with an increased link size, test 2 (and test 5 if - you are using UTF-8) will fail. Part of the output of these tests is a - representation of the compiled pattern, and this changes with the link - size. - - -AVOIDING EXCESSIVE STACK USAGE - - PCRE implements backtracking while matching by making recursive calls - to an internal function called match(). In environments where the size - of the stack is limited, this can severely limit PCRE's operation. (The - Unix environment does not usually suffer from this problem.) An alter- - native approach that uses memory from the heap to remember data, - instead of using recursive function calls, has been implemented to work - round this problem. If you want to build a version of PCRE that works - this way, add - - --disable-stack-for-recursion - - to the configure command. With this configuration, PCRE will use the - pcre_stack_malloc and pcre_stack_free variables to call memory manage- - ment functions. Separate functions are provided because the usage is - very predictable: the block sizes requested are always the same, and - the blocks are always freed in reverse order. A calling program might - be able to implement optimized functions that perform better than the - standard malloc() and free() functions. PCRE runs noticeably more - slowly when built in this way. - - -USING EBCDIC CODE - - PCRE assumes by default that it will run in an environment where the - character code is ASCII (or Unicode, which is a superset of ASCII). - PCRE can, however, be compiled to run in an EBCDIC environment by - adding - - --enable-ebcdic - - to the configure command. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PCRE NATIVE API - - #include - - pcre *pcre_compile(const char *pattern, int options, - const char **errptr, int *erroffset, - const unsigned char *tableptr); - - pcre_extra *pcre_study(const pcre *code, int options, - const char **errptr); - - int pcre_exec(const pcre *code, const pcre_extra *extra, - const char *subject, int length, int startoffset, - int options, int *ovector, int ovecsize); - - int pcre_copy_named_substring(const pcre *code, - const char *subject, int *ovector, - int stringcount, const char *stringname, - char *buffer, int buffersize); - - int pcre_copy_substring(const char *subject, int *ovector, - int stringcount, int stringnumber, char *buffer, - int buffersize); - - int pcre_get_named_substring(const pcre *code, - const char *subject, int *ovector, - int stringcount, const char *stringname, - const char **stringptr); - - int pcre_get_stringnumber(const pcre *code, - const char *name); - - int pcre_get_substring(const char *subject, int *ovector, - int stringcount, int stringnumber, - const char **stringptr); - - int pcre_get_substring_list(const char *subject, - int *ovector, int stringcount, const char ***listptr); - - void pcre_free_substring(const char *stringptr); - - void pcre_free_substring_list(const char **stringptr); - - const unsigned char *pcre_maketables(void); - - int pcre_fullinfo(const pcre *code, const pcre_extra *extra, - int what, void *where); - - int pcre_info(const pcre *code, int *optptr, int *firstcharptr); - - int pcre_config(int what, void *where); - - char *pcre_version(void); - - void *(*pcre_malloc)(size_t); - - void (*pcre_free)(void *); - - void *(*pcre_stack_malloc)(size_t); - - void (*pcre_stack_free)(void *); - - int (*pcre_callout)(pcre_callout_block *); - - -PCRE API OVERVIEW - - PCRE has its own native API, which is described in this document. There - is also a set of wrapper functions that correspond to the POSIX regular - expression API. These are described in the pcreposix documentation. - - The native API function prototypes are defined in the header file - pcre.h, and on Unix systems the library itself is called libpcre. It - can normally be accessed by adding -lpcre to the command for linking an - application that uses PCRE. The header file defines the macros - PCRE_MAJOR and PCRE_MINOR to contain the major and minor release num- - bers for the library. Applications can use these to include support - for different releases of PCRE. - - The functions pcre_compile(), pcre_study(), and pcre_exec() are used - for compiling and matching regular expressions. A sample program that - demonstrates the simplest way of using them is provided in the file - called pcredemo.c in the source distribution. The pcresample documenta- - tion describes how to run it. - - In addition to the main compiling and matching functions, there are - convenience functions for extracting captured substrings from a matched - subject string. They are: - - pcre_copy_substring() - pcre_copy_named_substring() - pcre_get_substring() - pcre_get_named_substring() - pcre_get_substring_list() - pcre_get_stringnumber() - - pcre_free_substring() and pcre_free_substring_list() are also provided, - to free the memory used for extracted strings. - - The function pcre_maketables() is used to build a set of character - tables in the current locale for passing to pcre_compile() or - pcre_exec(). This is an optional facility that is provided for spe- - cialist use. Most commonly, no special tables are passed, in which case - internal tables that are generated when PCRE is built are used. - - The function pcre_fullinfo() is used to find out information about a - compiled pattern; pcre_info() is an obsolete version that returns only - some of the available information, but is retained for backwards com- - patibility. The function pcre_version() returns a pointer to a string - containing the version of PCRE and its date of release. - - The global variables pcre_malloc and pcre_free initially contain the - entry points of the standard malloc() and free() functions, respec- - tively. PCRE calls the memory management functions via these variables, - so a calling program can replace them if it wishes to intercept the - calls. This should be done before calling any PCRE functions. - - The global variables pcre_stack_malloc and pcre_stack_free are also - indirections to memory management functions. These special functions - are used only when PCRE is compiled to use the heap for remembering - data, instead of recursive function calls. This is a non-standard way - of building PCRE, for use in environments that have limited stacks. - Because of the greater use of memory management, it runs more slowly. - Separate functions are provided so that special-purpose external code - can be used for this case. When used, these functions are always called - in a stack-like manner (last obtained, first freed), and always for - memory blocks of the same size. - - The global variable pcre_callout initially contains NULL. It can be set - by the caller to a "callout" function, which PCRE will then call at - specified points during a matching operation. Details are given in the - pcrecallout documentation. - - -MULTITHREADING - - The PCRE functions can be used in multi-threading applications, with - the proviso that the memory management functions pointed to by - pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the - callout function pointed to by pcre_callout, are shared by all threads. - - The compiled form of a regular expression is not altered during match- - ing, so the same compiled pattern can safely be used by several threads - at once. - - -SAVING PRECOMPILED PATTERNS FOR LATER USE - - The compiled form of a regular expression can be saved and re-used at a - later time, possibly by a different program, and even on a host other - than the one on which it was compiled. Details are given in the - pcreprecompile documentation. - - -CHECKING BUILD-TIME OPTIONS - - int pcre_config(int what, void *where); - - The function pcre_config() makes it possible for a PCRE client to dis- - cover which optional features have been compiled into the PCRE library. - The pcrebuild documentation has more details about these optional fea- - tures. - - The first argument for pcre_config() is an integer, specifying which - information is required; the second argument is a pointer to a variable - into which the information is placed. The following information is - available: - - PCRE_CONFIG_UTF8 - - The output is an integer that is set to one if UTF-8 support is avail- - able; otherwise it is set to zero. - - PCRE_CONFIG_UNICODE_PROPERTIES - - The output is an integer that is set to one if support for Unicode - character properties is available; otherwise it is set to zero. - - PCRE_CONFIG_NEWLINE - - The output is an integer that is set to the value of the code that is - used for the newline character. It is either linefeed (10) or carriage - return (13), and should normally be the standard character for your - operating system. - - PCRE_CONFIG_LINK_SIZE - - The output is an integer that contains the number of bytes used for - internal linkage in compiled regular expressions. The value is 2, 3, or - 4. Larger values allow larger regular expressions to be compiled, at - the expense of slower matching. The default value of 2 is sufficient - for all but the most massive patterns, since it allows the compiled - pattern to be up to 64K in size. - - PCRE_CONFIG_POSIX_MALLOC_THRESHOLD - - The output is an integer that contains the threshold above which the - POSIX interface uses malloc() for output vectors. Further details are - given in the pcreposix documentation. - - PCRE_CONFIG_MATCH_LIMIT - - The output is an integer that gives the default limit for the number of - internal matching function calls in a pcre_exec() execution. Further - details are given with pcre_exec() below. - - PCRE_CONFIG_STACKRECURSE - - The output is an integer that is set to one if internal recursion is - implemented by recursive function calls that use the stack to remember - their state. This is the usual way that PCRE is compiled. The output is - zero if PCRE was compiled to use blocks of data on the heap instead of - recursive function calls. In this case, pcre_stack_malloc and - pcre_stack_free are called to manage memory blocks on the heap, thus - avoiding the use of the stack. - - -COMPILING A PATTERN - - pcre *pcre_compile(const char *pattern, int options, - const char **errptr, int *erroffset, - const unsigned char *tableptr); - - The function pcre_compile() is called to compile a pattern into an - internal form. The pattern is a C string terminated by a binary zero, - and is passed in the pattern argument. A pointer to a single block of - memory that is obtained via pcre_malloc is returned. This contains the - compiled code and related data. The pcre type is defined for the - returned block; this is a typedef for a structure whose contents are - not externally defined. It is up to the caller to free the memory when - it is no longer required. - - Although the compiled code of a PCRE regex is relocatable, that is, it - does not depend on memory location, the complete pcre data block is not - fully relocatable, because it may contain a copy of the tableptr argu- - ment, which is an address (see below). - - The options argument contains independent bits that affect the compila- - tion. It should be zero if no options are required. The available - options are described below. Some of them, in particular, those that - are compatible with Perl, can also be set and unset from within the - pattern (see the detailed description in the pcrepattern documenta- - tion). For these options, the contents of the options argument speci- - fies their initial settings at the start of compilation and execution. - The PCRE_ANCHORED option can be set at the time of matching as well as - at compile time. - - If errptr is NULL, pcre_compile() returns NULL immediately. Otherwise, - if compilation of a pattern fails, pcre_compile() returns NULL, and - sets the variable pointed to by errptr to point to a textual error mes- - sage. The offset from the start of the pattern to the character where - the error was discovered is placed in the variable pointed to by - erroffset, which must not be NULL. If it is, an immediate error is - given. - - If the final argument, tableptr, is NULL, PCRE uses a default set of - character tables that are built when PCRE is compiled, using the - default C locale. Otherwise, tableptr must be an address that is the - result of a call to pcre_maketables(). This value is stored with the - compiled pattern, and used again by pcre_exec(), unless another table - pointer is passed to it. For more discussion, see the section on locale - support below. - - This code fragment shows a typical straightforward call to pcre_com- - pile(): - - pcre *re; - const char *error; - int erroffset; - re = pcre_compile( - "^A.*Z", /* the pattern */ - 0, /* default options */ - &error, /* for error message */ - &erroffset, /* for error offset */ - NULL); /* use default character tables */ - - The following names for option bits are defined in the pcre.h header - file: - - PCRE_ANCHORED - - If this bit is set, the pattern is forced to be "anchored", that is, it - is constrained to match only at the first matching point in the string - that is being searched (the "subject string"). This effect can also be - achieved by appropriate constructs in the pattern itself, which is the - only way to do it in Perl. - - PCRE_AUTO_CALLOUT - - If this bit is set, pcre_compile() automatically inserts callout items, - all with number 255, before each pattern item. For discussion of the - callout facility, see the pcrecallout documentation. - - PCRE_CASELESS - - If this bit is set, letters in the pattern match both upper and lower - case letters. It is equivalent to Perl's /i option, and it can be - changed within a pattern by a (?i) option setting. When running in - UTF-8 mode, case support for high-valued characters is available only - when PCRE is built with Unicode character property support. - - PCRE_DOLLAR_ENDONLY - - If this bit is set, a dollar metacharacter in the pattern matches only - at the end of the subject string. Without this option, a dollar also - matches immediately before the final character if it is a newline (but - not before any other newlines). The PCRE_DOLLAR_ENDONLY option is - ignored if PCRE_MULTILINE is set. There is no equivalent to this option - in Perl, and no way to set it within a pattern. - - PCRE_DOTALL - - If this bit is set, a dot metacharater in the pattern matches all char- - acters, including newlines. Without it, newlines are excluded. This - option is equivalent to Perl's /s option, and it can be changed within - a pattern by a (?s) option setting. A negative class such as [^a] - always matches a newline character, independent of the setting of this - option. - - PCRE_EXTENDED - - If this bit is set, whitespace data characters in the pattern are - totally ignored except when escaped or inside a character class. - Whitespace does not include the VT character (code 11). In addition, - characters between an unescaped # outside a character class and the - next newline character, inclusive, are also ignored. This is equivalent - to Perl's /x option, and it can be changed within a pattern by a (?x) - option setting. - - This option makes it possible to include comments inside complicated - patterns. Note, however, that this applies only to data characters. - Whitespace characters may never appear within special character - sequences in a pattern, for example within the sequence (?( which - introduces a conditional subpattern. - - PCRE_EXTRA - - This option was invented in order to turn on additional functionality - of PCRE that is incompatible with Perl, but it is currently of very - little use. When set, any backslash in a pattern that is followed by a - letter that has no special meaning causes an error, thus reserving - these combinations for future expansion. By default, as in Perl, a - backslash followed by a letter with no special meaning is treated as a - literal. There are at present no other features controlled by this - option. It can also be set by a (?X) option setting within a pattern. - - PCRE_MULTILINE - - By default, PCRE treats the subject string as consisting of a single - line of characters (even if it actually contains newlines). The "start - of line" metacharacter (^) matches only at the start of the string, - while the "end of line" metacharacter ($) matches only at the end of - the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY - is set). This is the same as Perl. - - When PCRE_MULTILINE it is set, the "start of line" and "end of line" - constructs match immediately following or immediately before any new- - line in the subject string, respectively, as well as at the very start - and end. This is equivalent to Perl's /m option, and it can be changed - within a pattern by a (?m) option setting. If there are no "\n" charac- - ters in a subject string, or no occurrences of ^ or $ in a pattern, - setting PCRE_MULTILINE has no effect. - - PCRE_NO_AUTO_CAPTURE - - If this option is set, it disables the use of numbered capturing paren- - theses in the pattern. Any opening parenthesis that is not followed by - ? behaves as if it were followed by ?: but named parentheses can still - be used for capturing (and they acquire numbers in the usual way). - There is no equivalent of this option in Perl. - - PCRE_UNGREEDY - - This option inverts the "greediness" of the quantifiers so that they - are not greedy by default, but become greedy if followed by "?". It is - not compatible with Perl. It can also be set by a (?U) option setting - within the pattern. - - PCRE_UTF8 - - This option causes PCRE to regard both the pattern and the subject as - strings of UTF-8 characters instead of single-byte character strings. - However, it is available only when PCRE is built to include UTF-8 sup- - port. If not, the use of this option provokes an error. Details of how - this option changes the behaviour of PCRE are given in the section on - UTF-8 support in the main pcre page. - - PCRE_NO_UTF8_CHECK - - When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is - automatically checked. If an invalid UTF-8 sequence of bytes is found, - pcre_compile() returns an error. If you already know that your pattern - is valid, and you want to skip this check for performance reasons, you - can set the PCRE_NO_UTF8_CHECK option. When it is set, the effect of - passing an invalid UTF-8 string as a pattern is undefined. It may cause - your program to crash. Note that this option can also be passed to - pcre_exec(), to suppress the UTF-8 validity checking of subject - strings. - - -STUDYING A PATTERN - - pcre_extra *pcre_study(const pcre *code, int options, - const char **errptr); - - If a compiled pattern is going to be used several times, it is worth - spending more time analyzing it in order to speed up the time taken for - matching. The function pcre_study() takes a pointer to a compiled pat- - tern as its first argument. If studying the pattern produces additional - information that will help speed up matching, pcre_study() returns a - pointer to a pcre_extra block, in which the study_data field points to - the results of the study. - - The returned value from pcre_study() can be passed directly to - pcre_exec(). However, a pcre_extra block also contains other fields - that can be set by the caller before the block is passed; these are - described below in the section on matching a pattern. - - If studying the pattern does not produce any additional information, - pcre_study() returns NULL. In that circumstance, if the calling program - wants to pass any of the other fields to pcre_exec(), it must set up - its own pcre_extra block. - - The second argument of pcre_study() contains option bits. At present, - no options are defined, and this argument should always be zero. - - The third argument for pcre_study() is a pointer for an error message. - If studying succeeds (even if no data is returned), the variable it - points to is set to NULL. Otherwise it points to a textual error mes- - sage. You should therefore test the error pointer for NULL after call- - ing pcre_study(), to be sure that it has run successfully. - - This is a typical call to pcre_study(): - - pcre_extra *pe; - pe = pcre_study( - re, /* result of pcre_compile() */ - 0, /* no options exist */ - &error); /* set to NULL or points to a message */ - - At present, studying a pattern is useful only for non-anchored patterns - that do not have a single fixed starting character. A bitmap of possi- - ble starting bytes is created. - - -LOCALE SUPPORT - - PCRE handles caseless matching, and determines whether characters are - letters, digits, or whatever, by reference to a set of tables, indexed - by character value. (When running in UTF-8 mode, this applies only to - characters with codes less than 128. Higher-valued codes never match - escapes such as \w or \d, but can be tested with \p if PCRE is built - with Unicode character property support.) - - An internal set of tables is created in the default C locale when PCRE - is built. This is used when the final argument of pcre_compile() is - NULL, and is sufficient for many applications. An alternative set of - tables can, however, be supplied. These may be created in a different - locale from the default. As more and more applications change to using - Unicode, the need for this locale support is expected to die away. - - External tables are built by calling the pcre_maketables() function, - which has no arguments, in the relevant locale. The result can then be - passed to pcre_compile() or pcre_exec() as often as necessary. For - example, to build and use tables that are appropriate for the French - locale (where accented characters with values greater than 128 are - treated as letters), the following code could be used: - - setlocale(LC_CTYPE, "fr_FR"); - tables = pcre_maketables(); - re = pcre_compile(..., tables); - - When pcre_maketables() runs, the tables are built in memory that is - obtained via pcre_malloc. It is the caller's responsibility to ensure - that the memory containing the tables remains available for as long as - it is needed. - - The pointer that is passed to pcre_compile() is saved with the compiled - pattern, and the same tables are used via this pointer by pcre_study() - and normally also by pcre_exec(). Thus, by default, for any single pat- - tern, compilation, studying and matching all happen in the same locale, - but different patterns can be compiled in different locales. - - It is possible to pass a table pointer or NULL (indicating the use of - the internal tables) to pcre_exec(). Although not intended for this - purpose, this facility could be used to match a pattern in a different - locale from the one in which it was compiled. Passing table pointers at - run time is discussed below in the section on matching a pattern. - - -INFORMATION ABOUT A PATTERN - - int pcre_fullinfo(const pcre *code, const pcre_extra *extra, - int what, void *where); - - The pcre_fullinfo() function returns information about a compiled pat- - tern. It replaces the obsolete pcre_info() function, which is neverthe- - less retained for backwards compability (and is documented below). - - The first argument for pcre_fullinfo() is a pointer to the compiled - pattern. The second argument is the result of pcre_study(), or NULL if - the pattern was not studied. The third argument specifies which piece - of information is required, and the fourth argument is a pointer to a - variable to receive the data. The yield of the function is zero for - success, or one of the following negative numbers: - - PCRE_ERROR_NULL the argument code was NULL - the argument where was NULL - PCRE_ERROR_BADMAGIC the "magic number" was not found - PCRE_ERROR_BADOPTION the value of what was invalid - - The "magic number" is placed at the start of each compiled pattern as - an simple check against passing an arbitrary memory pointer. Here is a - typical call of pcre_fullinfo(), to obtain the length of the compiled - pattern: - - int rc; - unsigned long int length; - rc = pcre_fullinfo( - re, /* result of pcre_compile() */ - pe, /* result of pcre_study(), or NULL */ - PCRE_INFO_SIZE, /* what is required */ - &length); /* where to put the data */ - - The possible values for the third argument are defined in pcre.h, and - are as follows: - - PCRE_INFO_BACKREFMAX - - Return the number of the highest back reference in the pattern. The - fourth argument should point to an int variable. Zero is returned if - there are no back references. - - PCRE_INFO_CAPTURECOUNT - - Return the number of capturing subpatterns in the pattern. The fourth - argument should point to an int variable. - - PCRE_INFO_DEFAULTTABLES - - Return a pointer to the internal default character tables within PCRE. - The fourth argument should point to an unsigned char * variable. This - information call is provided for internal use by the pcre_study() func- - tion. External callers can cause PCRE to use its internal tables by - passing a NULL table pointer. - - PCRE_INFO_FIRSTBYTE - - Return information about the first byte of any matched string, for a - non-anchored pattern. (This option used to be called - PCRE_INFO_FIRSTCHAR; the old name is still recognized for backwards - compatibility.) - - If there is a fixed first byte, for example, from a pattern such as - (cat|cow|coyote), it is returned in the integer pointed to by where. - Otherwise, if either - - (a) the pattern was compiled with the PCRE_MULTILINE option, and every - branch starts with "^", or - - (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not - set (if it were set, the pattern would be anchored), - - -1 is returned, indicating that the pattern matches only at the start - of a subject string or after any newline within the string. Otherwise - -2 is returned. For anchored patterns, -2 is returned. - - PCRE_INFO_FIRSTTABLE - - If the pattern was studied, and this resulted in the construction of a - 256-bit table indicating a fixed set of bytes for the first byte in any - matching string, a pointer to the table is returned. Otherwise NULL is - returned. The fourth argument should point to an unsigned char * vari- - able. - - PCRE_INFO_LASTLITERAL - - Return the value of the rightmost literal byte that must exist in any - matched string, other than at its start, if such a byte has been - recorded. The fourth argument should point to an int variable. If there - is no such byte, -1 is returned. For anchored patterns, a last literal - byte is recorded only if it follows something of variable length. For - example, for the pattern /^a\d+z\d+/ the returned value is "z", but for - /^a\dz\d/ the returned value is -1. - - PCRE_INFO_NAMECOUNT - PCRE_INFO_NAMEENTRYSIZE - PCRE_INFO_NAMETABLE - - PCRE supports the use of named as well as numbered capturing parenthe- - ses. The names are just an additional way of identifying the parenthe- - ses, which still acquire numbers. A convenience function called - pcre_get_named_substring() is provided for extracting an individual - captured substring by name. It is also possible to extract the data - directly, by first converting the name to a number in order to access - the correct pointers in the output vector (described with pcre_exec() - below). To do the conversion, you need to use the name-to-number map, - which is described by these three values. - - The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT - gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size - of each entry; both of these return an int value. The entry size - depends on the length of the longest name. PCRE_INFO_NAMETABLE returns - a pointer to the first entry of the table (a pointer to char). The - first two bytes of each entry are the number of the capturing parenthe- - sis, most significant byte first. The rest of the entry is the corre- - sponding name, zero terminated. The names are in alphabetical order. - For example, consider the following pattern (assume PCRE_EXTENDED is - set, so white space - including newlines - is ignored): - - (?P (?P(\d\d)?\d\d) - - (?P\d\d) - (?P\d\d) ) - - There are four named subpatterns, so the table has four entries, and - each entry in the table is eight bytes long. The table is as follows, - with non-printing bytes shows in hexadecimal, and undefined bytes shown - as ??: - - 00 01 d a t e 00 ?? - 00 05 d a y 00 ?? ?? - 00 04 m o n t h 00 - 00 02 y e a r 00 ?? - - When writing code to extract data from named subpatterns using the - name-to-number map, remember that the length of each entry is likely to - be different for each compiled pattern. - - PCRE_INFO_OPTIONS - - Return a copy of the options with which the pattern was compiled. The - fourth argument should point to an unsigned long int variable. These - option bits are those specified in the call to pcre_compile(), modified - by any top-level option settings within the pattern itself. - - A pattern is automatically anchored by PCRE if all of its top-level - alternatives begin with one of the following: - - ^ unless PCRE_MULTILINE is set - \A always - \G always - .* if PCRE_DOTALL is set and there are no back - references to the subpattern in which .* appears - - For such patterns, the PCRE_ANCHORED bit is set in the options returned - by pcre_fullinfo(). - - PCRE_INFO_SIZE - - Return the size of the compiled pattern, that is, the value that was - passed as the argument to pcre_malloc() when PCRE was getting memory in - which to place the compiled data. The fourth argument should point to a - size_t variable. - - PCRE_INFO_STUDYSIZE - - Return the size of the data block pointed to by the study_data field in - a pcre_extra block. That is, it is the value that was passed to - pcre_malloc() when PCRE was getting memory into which to place the data - created by pcre_study(). The fourth argument should point to a size_t - variable. - - -OBSOLETE INFO FUNCTION - - int pcre_info(const pcre *code, int *optptr, int *firstcharptr); - - The pcre_info() function is now obsolete because its interface is too - restrictive to return all the available data about a compiled pattern. - New programs should use pcre_fullinfo() instead. The yield of - pcre_info() is the number of capturing subpatterns, or one of the fol- - lowing negative numbers: - - PCRE_ERROR_NULL the argument code was NULL - PCRE_ERROR_BADMAGIC the "magic number" was not found - - If the optptr argument is not NULL, a copy of the options with which - the pattern was compiled is placed in the integer it points to (see - PCRE_INFO_OPTIONS above). - - If the pattern is not anchored and the firstcharptr argument is not - NULL, it is used to pass back information about the first character of - any matched string (see PCRE_INFO_FIRSTBYTE above). - - -MATCHING A PATTERN - - int pcre_exec(const pcre *code, const pcre_extra *extra, - const char *subject, int length, int startoffset, - int options, int *ovector, int ovecsize); - - The function pcre_exec() is called to match a subject string against a - compiled pattern, which is passed in the code argument. If the pattern - has been studied, the result of the study should be passed in the extra - argument. - - In most applications, the pattern will have been compiled (and option- - ally studied) in the same process that calls pcre_exec(). However, it - is possible to save compiled patterns and study data, and then use them - later in different processes, possibly even on different hosts. For a - discussion about this, see the pcreprecompile documentation. - - Here is an example of a simple call to pcre_exec(): - - int rc; - int ovector[30]; - rc = pcre_exec( - re, /* result of pcre_compile() */ - NULL, /* we didn't study the pattern */ - "some string", /* the subject string */ - 11, /* the length of the subject string */ - 0, /* start at offset 0 in the subject */ - 0, /* default options */ - ovector, /* vector of integers for substring information */ - 30); /* number of elements in the vector (NOT size in - bytes) */ - - Extra data for pcre_exec() - - If the extra argument is not NULL, it must point to a pcre_extra data - block. The pcre_study() function returns such a block (when it doesn't - return NULL), but you can also create one for yourself, and pass addi- - tional information in it. The fields in a pcre_extra block are as fol- - lows: - - unsigned long int flags; - void *study_data; - unsigned long int match_limit; - void *callout_data; - const unsigned char *tables; - - The flags field is a bitmap that specifies which of the other fields - are set. The flag bits are: - - PCRE_EXTRA_STUDY_DATA - PCRE_EXTRA_MATCH_LIMIT - PCRE_EXTRA_CALLOUT_DATA - PCRE_EXTRA_TABLES - - Other flag bits should be set to zero. The study_data field is set in - the pcre_extra block that is returned by pcre_study(), together with - the appropriate flag bit. You should not set this yourself, but you may - add to the block by setting the other fields and their corresponding - flag bits. - - The match_limit field provides a means of preventing PCRE from using up - a vast amount of resources when running patterns that are not going to - match, but which have a very large number of possibilities in their - search trees. The classic example is the use of nested unlimited - repeats. - - Internally, PCRE uses a function called match() which it calls repeat- - edly (sometimes recursively). The limit is imposed on the number of - times this function is called during a match, which has the effect of - limiting the amount of recursion and backtracking that can take place. - For patterns that are not anchored, the count starts from zero for each - position in the subject string. - - The default limit for the library can be set when PCRE is built; the - default default is 10 million, which handles all but the most extreme - cases. You can reduce the default by suppling pcre_exec() with a - pcre_extra block in which match_limit is set to a smaller value, and - PCRE_EXTRA_MATCH_LIMIT is set in the flags field. If the limit is - exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT. - - The pcre_callout field is used in conjunction with the "callout" fea- - ture, which is described in the pcrecallout documentation. - - The tables field is used to pass a character tables pointer to - pcre_exec(); this overrides the value that is stored with the compiled - pattern. A non-NULL value is stored with the compiled pattern only if - custom tables were supplied to pcre_compile() via its tableptr argu- - ment. If NULL is passed to pcre_exec() using this mechanism, it forces - PCRE's internal tables to be used. This facility is helpful when re- - using patterns that have been saved after compiling with an external - set of tables, because the external tables might be at a different - address when pcre_exec() is called. See the pcreprecompile documenta- - tion for a discussion of saving compiled patterns for later use. - - Option bits for pcre_exec() - - The unused bits of the options argument for pcre_exec() must be zero. - The only bits that may be set are PCRE_ANCHORED, PCRE_NOTBOL, - PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL. - - PCRE_ANCHORED - - The PCRE_ANCHORED option limits pcre_exec() to matching at the first - matching position. If a pattern was compiled with PCRE_ANCHORED, or - turned out to be anchored by virtue of its contents, it cannot be made - unachored at matching time. - - PCRE_NOTBOL - - This option specifies that first character of the subject string is not - the beginning of a line, so the circumflex metacharacter should not - match before it. Setting this without PCRE_MULTILINE (at compile time) - causes circumflex never to match. This option affects only the - behaviour of the circumflex metacharacter. It does not affect \A. - - PCRE_NOTEOL - - This option specifies that the end of the subject string is not the end - of a line, so the dollar metacharacter should not match it nor (except - in multiline mode) a newline immediately before it. Setting this with- - out PCRE_MULTILINE (at compile time) causes dollar never to match. This - option affects only the behaviour of the dollar metacharacter. It does - not affect \Z or \z. - - PCRE_NOTEMPTY - - An empty string is not considered to be a valid match if this option is - set. If there are alternatives in the pattern, they are tried. If all - the alternatives match the empty string, the entire match fails. For - example, if the pattern - - a?b? - - is applied to a string not beginning with "a" or "b", it matches the - empty string at the start of the subject. With PCRE_NOTEMPTY set, this - match is not valid, so PCRE searches further into the string for occur- - rences of "a" or "b". - - Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe- - cial case of a pattern match of the empty string within its split() - function, and when using the /g modifier. It is possible to emulate - Perl's behaviour after matching a null string by first trying the match - again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then - if that fails by advancing the starting offset (see below) and trying - an ordinary match again. There is some code that demonstrates how to do - this in the pcredemo.c sample program. - - PCRE_NO_UTF8_CHECK - - When PCRE_UTF8 is set at compile time, the validity of the subject as a - UTF-8 string is automatically checked when pcre_exec() is subsequently - called. The value of startoffset is also checked to ensure that it - points to the start of a UTF-8 character. If an invalid UTF-8 sequence - of bytes is found, pcre_exec() returns the error PCRE_ERROR_BADUTF8. If - startoffset contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is - returned. - - If you already know that your subject is valid, and you want to skip - these checks for performance reasons, you can set the - PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might want to - do this for the second and subsequent calls to pcre_exec() if you are - making repeated calls to find all the matches in a single subject - string. However, you should be sure that the value of startoffset - points to the start of a UTF-8 character. When PCRE_NO_UTF8_CHECK is - set, the effect of passing an invalid UTF-8 string as a subject, or a - value of startoffset that does not point to the start of a UTF-8 char- - acter, is undefined. Your program may crash. - - PCRE_PARTIAL - - This option turns on the partial matching feature. If the subject - string fails to match the pattern, but at some point during the match- - ing process the end of the subject was reached (that is, the subject - partially matches the pattern and the failure to match occurred only - because there were not enough subject characters), pcre_exec() returns - PCRE_ERROR_PARTIAL instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is - used, there are restrictions on what may appear in the pattern. These - are discussed in the pcrepartial documentation. - - The string to be matched by pcre_exec() - - The subject string is passed to pcre_exec() as a pointer in subject, a - length in length, and a starting byte offset in startoffset. In UTF-8 - mode, the byte offset must point to the start of a UTF-8 character. - Unlike the pattern string, the subject may contain binary zero bytes. - When the starting offset is zero, the search for a match starts at the - beginning of the subject, and this is by far the most common case. - - A non-zero starting offset is useful when searching for another match - in the same subject by calling pcre_exec() again after a previous suc- - cess. Setting startoffset differs from just passing over a shortened - string and setting PCRE_NOTBOL in the case of a pattern that begins - with any kind of lookbehind. For example, consider the pattern - - \Biss\B - - which finds occurrences of "iss" in the middle of words. (\B matches - only if the current position in the subject is not a word boundary.) - When applied to the string "Mississipi" the first call to pcre_exec() - finds the first occurrence. If pcre_exec() is called again with just - the remainder of the subject, namely "issipi", it does not match, - because \B is always false at the start of the subject, which is deemed - to be a word boundary. However, if pcre_exec() is passed the entire - string again, but with startoffset set to 4, it finds the second occur- - rence of "iss" because it is able to look behind the starting point to - discover that it is preceded by a letter. - - If a non-zero starting offset is passed when the pattern is anchored, - one attempt to match at the given offset is made. This can only succeed - if the pattern does not require the match to be at the start of the - subject. - - How pcre_exec() returns captured substrings - - In general, a pattern matches a certain portion of the subject, and in - addition, further substrings from the subject may be picked out by - parts of the pattern. Following the usage in Jeffrey Friedl's book, - this is called "capturing" in what follows, and the phrase "capturing - subpattern" is used for a fragment of a pattern that picks out a sub- - string. PCRE supports several other kinds of parenthesized subpattern - that do not cause substrings to be captured. - - Captured substrings are returned to the caller via a vector of integer - offsets whose address is passed in ovector. The number of elements in - the vector is passed in ovecsize, which must be a non-negative number. - Note: this argument is NOT the size of ovector in bytes. - - The first two-thirds of the vector is used to pass back captured sub- - strings, each substring using a pair of integers. The remaining third - of the vector is used as workspace by pcre_exec() while matching cap- - turing subpatterns, and is not available for passing back information. - The length passed in ovecsize should always be a multiple of three. If - it is not, it is rounded down. - - When a match is successful, information about captured substrings is - returned in pairs of integers, starting at the beginning of ovector, - and continuing up to two-thirds of its length at the most. The first - element of a pair is set to the offset of the first character in a sub- - string, and the second is set to the offset of the first character - after the end of a substring. The first pair, ovector[0] and ovec- - tor[1], identify the portion of the subject string matched by the - entire pattern. The next pair is used for the first capturing subpat- - tern, and so on. The value returned by pcre_exec() is the number of - pairs that have been set. If there are no capturing subpatterns, the - return value from a successful match is 1, indicating that just the - first pair of offsets has been set. - - Some convenience functions are provided for extracting the captured - substrings as separate strings. These are described in the following - section. - - It is possible for an capturing subpattern number n+1 to match some - part of the subject when subpattern n has not been used at all. For - example, if the string "abc" is matched against the pattern (a|(z))(bc) - subpatterns 1 and 3 are matched, but 2 is not. When this happens, both - offset values corresponding to the unused subpattern are set to -1. - - If a capturing subpattern is matched repeatedly, it is the last portion - of the string that it matched that is returned. - - If the vector is too small to hold all the captured substring offsets, - it is used as far as possible (up to two-thirds of its length), and the - function returns a value of zero. In particular, if the substring off- - sets are not of interest, pcre_exec() may be called with ovector passed - as NULL and ovecsize as zero. However, if the pattern contains back - references and the ovector is not big enough to remember the related - substrings, PCRE has to get additional memory for use during matching. - Thus it is usually advisable to supply an ovector. - - Note that pcre_info() can be used to find out how many capturing sub- - patterns there are in a compiled pattern. The smallest size for ovector - that will allow for n captured substrings, in addition to the offsets - of the substring matched by the whole pattern, is (n+1)*3. - - Return values from pcre_exec() - - If pcre_exec() fails, it returns a negative number. The following are - defined in the header file: - - PCRE_ERROR_NOMATCH (-1) - - The subject string did not match the pattern. - - PCRE_ERROR_NULL (-2) - - Either code or subject was passed as NULL, or ovector was NULL and - ovecsize was not zero. - - PCRE_ERROR_BADOPTION (-3) - - An unrecognized bit was set in the options argument. - - PCRE_ERROR_BADMAGIC (-4) - - PCRE stores a 4-byte "magic number" at the start of the compiled code, - to catch the case when it is passed a junk pointer and to detect when a - pattern that was compiled in an environment of one endianness is run in - an environment with the other endianness. This is the error that PCRE - gives when the magic number is not present. - - PCRE_ERROR_UNKNOWN_NODE (-5) - - While running the pattern match, an unknown item was encountered in the - compiled pattern. This error could be caused by a bug in PCRE or by - overwriting of the compiled pattern. - - PCRE_ERROR_NOMEMORY (-6) - - If a pattern contains back references, but the ovector that is passed - to pcre_exec() is not big enough to remember the referenced substrings, - PCRE gets a block of memory at the start of matching to use for this - purpose. If the call via pcre_malloc() fails, this error is given. The - memory is automatically freed at the end of matching. - - PCRE_ERROR_NOSUBSTRING (-7) - - This error is used by the pcre_copy_substring(), pcre_get_substring(), - and pcre_get_substring_list() functions (see below). It is never - returned by pcre_exec(). - - PCRE_ERROR_MATCHLIMIT (-8) - - The recursion and backtracking limit, as specified by the match_limit - field in a pcre_extra structure (or defaulted) was reached. See the - description above. - - PCRE_ERROR_CALLOUT (-9) - - This error is never generated by pcre_exec() itself. It is provided for - use by callout functions that want to yield a distinctive error code. - See the pcrecallout documentation for details. - - PCRE_ERROR_BADUTF8 (-10) - - A string that contains an invalid UTF-8 byte sequence was passed as a - subject. - - PCRE_ERROR_BADUTF8_OFFSET (-11) - - The UTF-8 byte sequence that was passed as a subject was valid, but the - value of startoffset did not point to the beginning of a UTF-8 charac- - ter. - - PCRE_ERROR_PARTIAL (-12) - - The subject string did not match, but it did match partially. See the - pcrepartial documentation for details of partial matching. - - PCRE_ERROR_BAD_PARTIAL (-13) - - The PCRE_PARTIAL option was used with a compiled pattern containing - items that are not supported for partial matching. See the pcrepartial - documentation for details of partial matching. - - PCRE_ERROR_INTERNAL (-14) - - An unexpected internal error has occurred. This error could be caused - by a bug in PCRE or by overwriting of the compiled pattern. - - PCRE_ERROR_BADCOUNT (-15) - - This error is given if the value of the ovecsize argument is negative. - - -EXTRACTING CAPTURED SUBSTRINGS BY NUMBER - - int pcre_copy_substring(const char *subject, int *ovector, - int stringcount, int stringnumber, char *buffer, - int buffersize); - - int pcre_get_substring(const char *subject, int *ovector, - int stringcount, int stringnumber, - const char **stringptr); - - int pcre_get_substring_list(const char *subject, - int *ovector, int stringcount, const char ***listptr); - - Captured substrings can be accessed directly by using the offsets - returned by pcre_exec() in ovector. For convenience, the functions - pcre_copy_substring(), pcre_get_substring(), and pcre_get_sub- - string_list() are provided for extracting captured substrings as new, - separate, zero-terminated strings. These functions identify substrings - by number. The next section describes functions for extracting named - substrings. A substring that contains a binary zero is correctly - extracted and has a further zero added on the end, but the result is - not, of course, a C string. - - The first three arguments are the same for all three of these func- - tions: subject is the subject string that has just been successfully - matched, ovector is a pointer to the vector of integer offsets that was - passed to pcre_exec(), and stringcount is the number of substrings that - were captured by the match, including the substring that matched the - entire regular expression. This is the value returned by pcre_exec() if - it is greater than zero. If pcre_exec() returned zero, indicating that - it ran out of space in ovector, the value passed as stringcount should - be the number of elements in the vector divided by three. - - The functions pcre_copy_substring() and pcre_get_substring() extract a - single substring, whose number is given as stringnumber. A value of - zero extracts the substring that matched the entire pattern, whereas - higher values extract the captured substrings. For pcre_copy_sub- - string(), the string is placed in buffer, whose length is given by - buffersize, while for pcre_get_substring() a new block of memory is - obtained via pcre_malloc, and its address is returned via stringptr. - The yield of the function is the length of the string, not including - the terminating zero, or one of - - PCRE_ERROR_NOMEMORY (-6) - - The buffer was too small for pcre_copy_substring(), or the attempt to - get memory failed for pcre_get_substring(). - - PCRE_ERROR_NOSUBSTRING (-7) - - There is no substring whose number is stringnumber. - - The pcre_get_substring_list() function extracts all available sub- - strings and builds a list of pointers to them. All this is done in a - single block of memory that is obtained via pcre_malloc. The address of - the memory block is returned via listptr, which is also the start of - the list of string pointers. The end of the list is marked by a NULL - pointer. The yield of the function is zero if all went well, or - - PCRE_ERROR_NOMEMORY (-6) - - if the attempt to get the memory block failed. - - When any of these functions encounter a substring that is unset, which - can happen when capturing subpattern number n+1 matches some part of - the subject, but subpattern n has not been used at all, they return an - empty string. This can be distinguished from a genuine zero-length sub- - string by inspecting the appropriate offset in ovector, which is nega- - tive for unset substrings. - - The two convenience functions pcre_free_substring() and pcre_free_sub- - string_list() can be used to free the memory returned by a previous - call of pcre_get_substring() or pcre_get_substring_list(), respec- - tively. They do nothing more than call the function pointed to by - pcre_free, which of course could be called directly from a C program. - However, PCRE is used in some situations where it is linked via a spe- - cial interface to another programming language which cannot use - pcre_free directly; it is for these cases that the functions are - provided. - - -EXTRACTING CAPTURED SUBSTRINGS BY NAME - - int pcre_get_stringnumber(const pcre *code, - const char *name); - - int pcre_copy_named_substring(const pcre *code, - const char *subject, int *ovector, - int stringcount, const char *stringname, - char *buffer, int buffersize); - - int pcre_get_named_substring(const pcre *code, - const char *subject, int *ovector, - int stringcount, const char *stringname, - const char **stringptr); - - To extract a substring by name, you first have to find associated num- - ber. For example, for this pattern - - (a+)b(?\d+)... - - the number of the subpattern called "xxx" is 2. You can find the number - from the name by calling pcre_get_stringnumber(). The first argument is - the compiled pattern, and the second is the name. The yield of the - function is the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if - there is no subpattern of that name. - - Given the number, you can extract the substring directly, or use one of - the functions described in the previous section. For convenience, there - are also two functions that do the whole job. - - Most of the arguments of pcre_copy_named_substring() and - pcre_get_named_substring() are the same as those for the similarly - named functions that extract by number. As these are described in the - previous section, they are not re-described here. There are just two - differences: - - First, instead of a substring number, a substring name is given. Sec- - ond, there is an extra argument, given at the start, which is a pointer - to the compiled pattern. This is needed in order to gain access to the - name-to-number translation table. - - These functions call pcre_get_stringnumber(), and if it succeeds, they - then call pcre_copy_substring() or pcre_get_substring(), as appropri- - ate. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PCRE CALLOUTS - - int (*pcre_callout)(pcre_callout_block *); - - PCRE provides a feature called "callout", which is a means of temporar- - ily passing control to the caller of PCRE in the middle of pattern - matching. The caller of PCRE provides an external function by putting - its entry point in the global variable pcre_callout. By default, this - variable contains NULL, which disables all calling out. - - Within a regular expression, (?C) indicates the points at which the - external function is to be called. Different callout points can be - identified by putting a number less than 256 after the letter C. The - default value is zero. For example, this pattern has two callout - points: - - (?C1)eabc(?C2)def - - If the PCRE_AUTO_CALLOUT option bit is set when pcre_compile() is - called, PCRE automatically inserts callouts, all with number 255, - before each item in the pattern. For example, if PCRE_AUTO_CALLOUT is - used with the pattern - - A(\d{2}|--) - - it is processed as if it were - - (?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255) - - Notice that there is a callout before and after each parenthesis and - alternation bar. Automatic callouts can be used for tracking the - progress of pattern matching. The pcretest command has an option that - sets automatic callouts; when it is used, the output indicates how the - pattern is matched. This is useful information when you are trying to - optimize the performance of a particular pattern. - - -MISSING CALLOUTS - - You should be aware that, because of optimizations in the way PCRE - matches patterns, callouts sometimes do not happen. For example, if the - pattern is - - ab(?C4)cd - - PCRE knows that any matching string must contain the letter "d". If the - subject string is "abyz", the lack of "d" means that matching doesn't - ever start, and the callout is never reached. However, with "abyd", - though the result is still no match, the callout is obeyed. - - -THE CALLOUT INTERFACE - - During matching, when PCRE reaches a callout point, the external func- - tion defined by pcre_callout is called (if it is set). The only argu- - ment is a pointer to a pcre_callout block. This structure contains the - following fields: - - int version; - int callout_number; - int *offset_vector; - const char *subject; - int subject_length; - int start_match; - int current_position; - int capture_top; - int capture_last; - void *callout_data; - int pattern_position; - int next_item_length; - - The version field is an integer containing the version number of the - block format. The initial version was 0; the current version is 1. The - version number will change again in future if additional fields are - added, but the intention is never to remove any of the existing fields. - - The callout_number field contains the number of the callout, as com- - piled into the pattern (that is, the number after ?C for manual call- - outs, and 255 for automatically generated callouts). - - The offset_vector field is a pointer to the vector of offsets that was - passed by the caller to pcre_exec(). The contents can be inspected in - order to extract substrings that have been matched so far, in the same - way as for extracting substrings after a match has completed. - - The subject and subject_length fields contain copies of the values that - were passed to pcre_exec(). - - The start_match field contains the offset within the subject at which - the current match attempt started. If the pattern is not anchored, the - callout function may be called several times from the same point in the - pattern for different starting points in the subject. - - The current_position field contains the offset within the subject of - the current match pointer. - - The capture_top field contains one more than the number of the highest - numbered captured substring so far. If no substrings have been cap- - tured, the value of capture_top is one. - - The capture_last field contains the number of the most recently cap- - tured substring. If no substrings have been captured, its value is -1. - - The callout_data field contains a value that is passed to pcre_exec() - by the caller specifically so that it can be passed back in callouts. - It is passed in the pcre_callout field of the pcre_extra data struc- - ture. If no such data was passed, the value of callout_data in a - pcre_callout block is NULL. There is a description of the pcre_extra - structure in the pcreapi documentation. - - The pattern_position field is present from version 1 of the pcre_call- - out structure. It contains the offset to the next item to be matched in - the pattern string. - - The next_item_length field is present from version 1 of the pcre_call- - out structure. It contains the length of the next item to be matched in - the pattern string. When the callout immediately precedes an alterna- - tion bar, a closing parenthesis, or the end of the pattern, the length - is zero. When the callout precedes an opening parenthesis, the length - is that of the entire subpattern. - - The pattern_position and next_item_length fields are intended to help - in distinguishing between different automatic callouts, which all have - the same callout number. However, they are set for all callouts. - - -RETURN VALUES - - The external callout function returns an integer to PCRE. If the value - is zero, matching proceeds as normal. If the value is greater than - zero, matching fails at the current point, but backtracking to test - other matching possibilities goes ahead, just as if a lookahead asser- - tion had failed. If the value is less than zero, the match is aban- - doned, and pcre_exec() returns the negative value. - - Negative values should normally be chosen from the set of - PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan- - dard "no match" failure. The error number PCRE_ERROR_CALLOUT is - reserved for use by callout functions; it will never be used by PCRE - itself. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -DIFFERENCES BETWEEN PCRE AND PERL - - This document describes the differences in the ways that PCRE and Perl - handle regular expressions. The differences described here are with - respect to Perl 5.8. - - 1. PCRE does not have full UTF-8 support. Details of what it does have - are given in the section on UTF-8 support in the main pcre page. - - 2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl - permits them, but they do not mean what you might think. For example, - (?!a){3} does not assert that the next three characters are not "a". It - just asserts that the next character is not "a" three times. - - 3. Capturing subpatterns that occur inside negative lookahead asser- - tions are counted, but their entries in the offsets vector are never - set. Perl sets its numerical variables from any such patterns that are - matched before the assertion fails to match something (thereby succeed- - ing), but only if the negative lookahead assertion contains just one - branch. - - 4. Though binary zero characters are supported in the subject string, - they are not allowed in a pattern string because it is passed as a nor- - mal C string, terminated by zero. The escape sequence \0 can be used in - the pattern to represent a binary zero. - - 5. The following Perl escape sequences are not supported: \l, \u, \L, - \U, and \N. In fact these are implemented by Perl's general string-han- - dling and are not part of its pattern matching engine. If any of these - are encountered by PCRE, an error is generated. - - 6. The Perl escape sequences \p, \P, and \X are supported only if PCRE - is built with Unicode character property support. The properties that - can be tested with \p and \P are limited to the general category prop- - erties such as Lu and Nd. - - 7. PCRE does support the \Q...\E escape for quoting substrings. Charac- - ters in between are treated as literals. This is slightly different - from Perl in that $ and @ are also handled as literals inside the - quotes. In Perl, they cause variable interpolation (but of course PCRE - does not have variables). Note the following examples: - - Pattern PCRE matches Perl matches - - \Qabc$xyz\E abc$xyz abc followed by the - contents of $xyz - \Qabc\$xyz\E abc\$xyz abc\$xyz - \Qabc\E\$\Qxyz\E abc$xyz abc$xyz - - The \Q...\E sequence is recognized both inside and outside character - classes. - - 8. Fairly obviously, PCRE does not support the (?{code}) and (?p{code}) - constructions. However, there is support for recursive patterns using - the non-Perl items (?R), (?number), and (?P>name). Also, the PCRE - "callout" feature allows an external function to be called during pat- - tern matching. See the pcrecallout documentation for details. - - 9. There are some differences that are concerned with the settings of - captured strings when part of a pattern is repeated. For example, - matching "aba" against the pattern /^(a(b)?)+$/ in Perl leaves $2 - unset, but in PCRE it is set to "b". - - 10. PCRE provides some extensions to the Perl regular expression facil- - ities: - - (a) Although lookbehind assertions must match fixed length strings, - each alternative branch of a lookbehind assertion can match a different - length of string. Perl requires them all to have the same length. - - (b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ - meta-character matches only at the very end of the string. - - (c) If PCRE_EXTRA is set, a backslash followed by a letter with no spe- - cial meaning is faulted. - - (d) If PCRE_UNGREEDY is set, the greediness of the repetition quanti- - fiers is inverted, that is, by default they are not greedy, but if fol- - lowed by a question mark they are. - - (e) PCRE_ANCHORED can be used at matching time to force a pattern to be - tried only at the first matching position in the subject string. - - (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAP- - TURE options for pcre_exec() have no Perl equivalents. - - (g) The (?R), (?number), and (?P>name) constructs allows for recursive - pattern matching (Perl can do this using the (?p{code}) construct, - which PCRE cannot support.) - - (h) PCRE supports named capturing substrings, using the Python syntax. - - (i) PCRE supports the possessive quantifier "++" syntax, taken from - Sun's Java package. - - (j) The (R) condition, for testing recursion, is a PCRE extension. - - (k) The callout facility is PCRE-specific. - - (l) The partial matching facility is PCRE-specific. - - (m) Patterns compiled by PCRE can be saved and re-used at a later time, - even on different hosts that have the other endianness. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PCRE REGULAR EXPRESSION DETAILS - - The syntax and semantics of the regular expressions supported by PCRE - are described below. Regular expressions are also described in the Perl - documentation and in a number of books, some of which have copious - examples. Jeffrey Friedl's "Mastering Regular Expressions", published - by O'Reilly, covers regular expressions in great detail. This descrip- - tion of PCRE's regular expressions is intended as reference material. - - The original operation of PCRE was on strings of one-byte characters. - However, there is now also support for UTF-8 character strings. To use - this, you must build PCRE to include UTF-8 support, and then call - pcre_compile() with the PCRE_UTF8 option. How this affects pattern - matching is mentioned in several places below. There is also a summary - of UTF-8 features in the section on UTF-8 support in the main pcre - page. - - A regular expression is a pattern that is matched against a subject - string from left to right. Most characters stand for themselves in a - pattern, and match the corresponding characters in the subject. As a - trivial example, the pattern - - The quick brown fox - - matches a portion of a subject string that is identical to itself. The - power of regular expressions comes from the ability to include alterna- - tives and repetitions in the pattern. These are encoded in the pattern - by the use of metacharacters, which do not stand for themselves but - instead are interpreted in some special way. - - There are two different sets of metacharacters: those that are recog- - nized anywhere in the pattern except within square brackets, and those - that are recognized in square brackets. Outside square brackets, the - metacharacters are as follows: - - \ general escape character with several uses - ^ assert start of string (or line, in multiline mode) - $ assert end of string (or line, in multiline mode) - . match any character except newline (by default) - [ start character class definition - | start of alternative branch - ( start subpattern - ) end subpattern - ? extends the meaning of ( - also 0 or 1 quantifier - also quantifier minimizer - * 0 or more quantifier - + 1 or more quantifier - also "possessive quantifier" - { start min/max quantifier - - Part of a pattern that is in square brackets is called a "character - class". In a character class the only metacharacters are: - - \ general escape character - ^ negate the class, but only if the first character - - indicates character range - [ POSIX character class (only if followed by POSIX - syntax) - ] terminates the character class - - The following sections describe the use of each of the metacharacters. - - -BACKSLASH - - The backslash character has several uses. Firstly, if it is followed by - a non-alphanumeric character, it takes away any special meaning that - character may have. This use of backslash as an escape character - applies both inside and outside character classes. - - For example, if you want to match a * character, you write \* in the - pattern. This escaping action applies whether or not the following - character would otherwise be interpreted as a metacharacter, so it is - always safe to precede a non-alphanumeric with backslash to specify - that it stands for itself. In particular, if you want to match a back- - slash, you write \\. - - If a pattern is compiled with the PCRE_EXTENDED option, whitespace in - the pattern (other than in a character class) and characters between a - # outside a character class and the next newline character are ignored. - An escaping backslash can be used to include a whitespace or # charac- - ter as part of the pattern. - - If you want to remove the special meaning from a sequence of charac- - ters, you can do so by putting them between \Q and \E. This is differ- - ent from Perl in that $ and @ are handled as literals in \Q...\E - sequences in PCRE, whereas in Perl, $ and @ cause variable interpola- - tion. Note the following examples: - - Pattern PCRE matches Perl matches - - \Qabc$xyz\E abc$xyz abc followed by the - contents of $xyz - \Qabc\$xyz\E abc\$xyz abc\$xyz - \Qabc\E\$\Qxyz\E abc$xyz abc$xyz - - The \Q...\E sequence is recognized both inside and outside character - classes. - - Non-printing characters - - A second use of backslash provides a way of encoding non-printing char- - acters in patterns in a visible manner. There is no restriction on the - appearance of non-printing characters, apart from the binary zero that - terminates a pattern, but when a pattern is being prepared by text - editing, it is usually easier to use one of the following escape - sequences than the binary character it represents: - - \a alarm, that is, the BEL character (hex 07) - \cx "control-x", where x is any character - \e escape (hex 1B) - \f formfeed (hex 0C) - \n newline (hex 0A) - \r carriage return (hex 0D) - \t tab (hex 09) - \ddd character with octal code ddd, or backreference - \xhh character with hex code hh - \x{hhh..} character with hex code hhh... (UTF-8 mode only) - - The precise effect of \cx is as follows: if x is a lower case letter, - it is converted to upper case. Then bit 6 of the character (hex 40) is - inverted. Thus \cz becomes hex 1A, but \c{ becomes hex 3B, while \c; - becomes hex 7B. - - After \x, from zero to two hexadecimal digits are read (letters can be - in upper or lower case). In UTF-8 mode, any number of hexadecimal dig- - its may appear between \x{ and }, but the value of the character code - must be less than 2**31 (that is, the maximum hexadecimal value is - 7FFFFFFF). If characters other than hexadecimal digits appear between - \x{ and }, or if there is no terminating }, this form of escape is not - recognized. Instead, the initial \x will be interpreted as a basic hex- - adecimal escape, with no following digits, giving a character whose - value is zero. - - Characters whose value is less than 256 can be defined by either of the - two syntaxes for \x when PCRE is in UTF-8 mode. There is no difference - in the way they are handled. For example, \xdc is exactly the same as - \x{dc}. - - After \0 up to two further octal digits are read. In both cases, if - there are fewer than two digits, just those that are present are used. - Thus the sequence \0\x\07 specifies two binary zeros followed by a BEL - character (code value 7). Make sure you supply two digits after the - initial zero if the pattern character that follows is itself an octal - digit. - - The handling of a backslash followed by a digit other than 0 is compli- - cated. Outside a character class, PCRE reads it and any following dig- - its as a decimal number. If the number is less than 10, or if there - have been at least that many previous capturing left parentheses in the - expression, the entire sequence is taken as a back reference. A - description of how this works is given later, following the discussion - of parenthesized subpatterns. - - Inside a character class, or if the decimal number is greater than 9 - and there have not been that many capturing subpatterns, PCRE re-reads - up to three octal digits following the backslash, and generates a sin- - gle byte from the least significant 8 bits of the value. Any subsequent - digits stand for themselves. For example: - - \040 is another way of writing a space - \40 is the same, provided there are fewer than 40 - previous capturing subpatterns - \7 is always a back reference - \11 might be a back reference, or another way of - writing a tab - \011 is always a tab - \0113 is a tab followed by the character "3" - \113 might be a back reference, otherwise the - character with octal code 113 - \377 might be a back reference, otherwise - the byte consisting entirely of 1 bits - \81 is either a back reference, or a binary zero - followed by the two characters "8" and "1" - - Note that octal values of 100 or greater must not be introduced by a - leading zero, because no more than three octal digits are ever read. - - All the sequences that define a single byte value or a single UTF-8 - character (in UTF-8 mode) can be used both inside and outside character - classes. In addition, inside a character class, the sequence \b is - interpreted as the backspace character (hex 08), and the sequence \X is - interpreted as the character "X". Outside a character class, these - sequences have different meanings (see below). - - Generic character types - - The third use of backslash is for specifying generic character types. - The following are always recognized: - - \d any decimal digit - \D any character that is not a decimal digit - \s any whitespace character - \S any character that is not a whitespace character - \w any "word" character - \W any "non-word" character - - Each pair of escape sequences partitions the complete set of characters - into two disjoint sets. Any given character matches one, and only one, - of each pair. - - These character type sequences can appear both inside and outside char- - acter classes. They each match one character of the appropriate type. - If the current matching point is at the end of the subject string, all - of them fail, since there is no character to match. - - For compatibility with Perl, \s does not match the VT character (code - 11). This makes it different from the the POSIX "space" class. The \s - characters are HT (9), LF (10), FF (12), CR (13), and space (32). - - A "word" character is an underscore or any character less than 256 that - is a letter or digit. The definition of letters and digits is con- - trolled by PCRE's low-valued character tables, and may vary if locale- - specific matching is taking place (see "Locale support" in the pcreapi - page). For example, in the "fr_FR" (French) locale, some character - codes greater than 128 are used for accented letters, and these are - matched by \w. - - In UTF-8 mode, characters with values greater than 128 never match \d, - \s, or \w, and always match \D, \S, and \W. This is true even when Uni- - code character property support is available. - - Unicode character properties - - When PCRE is built with Unicode character property support, three addi- - tional escape sequences to match generic character types are available - when UTF-8 mode is selected. They are: - - \p{xx} a character with the xx property - \P{xx} a character without the xx property - \X an extended Unicode sequence - - The property names represented by xx above are limited to the Unicode - general category properties. Each character has exactly one such prop- - erty, specified by a two-letter abbreviation. For compatibility with - Perl, negation can be specified by including a circumflex between the - opening brace and the property name. For example, \p{^Lu} is the same - as \P{Lu}. - - If only one letter is specified with \p or \P, it includes all the - properties that start with that letter. In this case, in the absence of - negation, the curly brackets in the escape sequence are optional; these - two examples have the same effect: - - \p{L} - \pL - - The following property codes are supported: - - C Other - Cc Control - Cf Format - Cn Unassigned - Co Private use - Cs Surrogate - - L Letter - Ll Lower case letter - Lm Modifier letter - Lo Other letter - Lt Title case letter - Lu Upper case letter - - M Mark - Mc Spacing mark - Me Enclosing mark - Mn Non-spacing mark - - N Number - Nd Decimal number - Nl Letter number - No Other number - - P Punctuation - Pc Connector punctuation - Pd Dash punctuation - Pe Close punctuation - Pf Final punctuation - Pi Initial punctuation - Po Other punctuation - Ps Open punctuation - - S Symbol - Sc Currency symbol - Sk Modifier symbol - Sm Mathematical symbol - So Other symbol - - Z Separator - Zl Line separator - Zp Paragraph separator - Zs Space separator - - Extended properties such as "Greek" or "InMusicalSymbols" are not sup- - ported by PCRE. - - Specifying caseless matching does not affect these escape sequences. - For example, \p{Lu} always matches only upper case letters. - - The \X escape matches any number of Unicode characters that form an - extended Unicode sequence. \X is equivalent to - - (?>\PM\pM*) - - That is, it matches a character without the "mark" property, followed - by zero or more characters with the "mark" property, and treats the - sequence as an atomic group (see below). Characters with the "mark" - property are typically accents that affect the preceding character. - - Matching characters by Unicode property is not fast, because PCRE has - to search a structure that contains data for over fifteen thousand - characters. That is why the traditional escape sequences such as \d and - \w do not use Unicode properties in PCRE. - - Simple assertions - - The fourth use of backslash is for certain simple assertions. An asser- - tion specifies a condition that has to be met at a particular point in - a match, without consuming any characters from the subject string. The - use of subpatterns for more complicated assertions is described below. - The backslashed assertions are: - - \b matches at a word boundary - \B matches when not at a word boundary - \A matches at start of subject - \Z matches at end of subject or before newline at end - \z matches at end of subject - \G matches at first matching position in subject - - These assertions may not appear in character classes (but note that \b - has a different meaning, namely the backspace character, inside a char- - acter class). - - A word boundary is a position in the subject string where the current - character and the previous character do not both match \w or \W (i.e. - one matches \w and the other matches \W), or the start or end of the - string if the first or last character matches \w, respectively. - - The \A, \Z, and \z assertions differ from the traditional circumflex - and dollar (described in the next section) in that they only ever match - at the very start and end of the subject string, whatever options are - set. Thus, they are independent of multiline mode. These three asser- - tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which - affect only the behaviour of the circumflex and dollar metacharacters. - However, if the startoffset argument of pcre_exec() is non-zero, indi- - cating that matching is to start at a point other than the beginning of - the subject, \A can never match. The difference between \Z and \z is - that \Z matches before a newline that is the last character of the - string as well as at the end of the string, whereas \z matches only at - the end. - - The \G assertion is true only when the current matching position is at - the start point of the match, as specified by the startoffset argument - of pcre_exec(). It differs from \A when the value of startoffset is - non-zero. By calling pcre_exec() multiple times with appropriate argu- - ments, you can mimic Perl's /g option, and it is in this kind of imple- - mentation where \G can be useful. - - Note, however, that PCRE's interpretation of \G, as the start of the - current match, is subtly different from Perl's, which defines it as the - end of the previous match. In Perl, these can be different when the - previously matched string was empty. Because PCRE does just one match - at a time, it cannot reproduce this behaviour. - - If all the alternatives of a pattern begin with \G, the expression is - anchored to the starting match position, and the "anchored" flag is set - in the compiled regular expression. - - -CIRCUMFLEX AND DOLLAR - - Outside a character class, in the default matching mode, the circumflex - character is an assertion that is true only if the current matching - point is at the start of the subject string. If the startoffset argu- - ment of pcre_exec() is non-zero, circumflex can never match if the - PCRE_MULTILINE option is unset. Inside a character class, circumflex - has an entirely different meaning (see below). - - Circumflex need not be the first character of the pattern if a number - of alternatives are involved, but it should be the first thing in each - alternative in which it appears if the pattern is ever to match that - branch. If all possible alternatives start with a circumflex, that is, - if the pattern is constrained to match only at the start of the sub- - ject, it is said to be an "anchored" pattern. (There are also other - constructs that can cause a pattern to be anchored.) - - A dollar character is an assertion that is true only if the current - matching point is at the end of the subject string, or immediately - before a newline character that is the last character in the string (by - default). Dollar need not be the last character of the pattern if a - number of alternatives are involved, but it should be the last item in - any branch in which it appears. Dollar has no special meaning in a - character class. - - The meaning of dollar can be changed so that it matches only at the - very end of the string, by setting the PCRE_DOLLAR_ENDONLY option at - compile time. This does not affect the \Z assertion. - - The meanings of the circumflex and dollar characters are changed if the - PCRE_MULTILINE option is set. When this is the case, they match immedi- - ately after and immediately before an internal newline character, - respectively, in addition to matching at the start and end of the sub- - ject string. For example, the pattern /^abc$/ matches the subject - string "def\nabc" (where \n represents a newline character) in multi- - line mode, but not otherwise. Consequently, patterns that are anchored - in single line mode because all branches start with ^ are not anchored - in multiline mode, and a match for circumflex is possible when the - startoffset argument of pcre_exec() is non-zero. The PCRE_DOL- - LAR_ENDONLY option is ignored if PCRE_MULTILINE is set. - - Note that the sequences \A, \Z, and \z can be used to match the start - and end of the subject in both modes, and if all branches of a pattern - start with \A it is always anchored, whether PCRE_MULTILINE is set or - not. - - -FULL STOP (PERIOD, DOT) - - Outside a character class, a dot in the pattern matches any one charac- - ter in the subject, including a non-printing character, but not (by - default) newline. In UTF-8 mode, a dot matches any UTF-8 character, - which might be more than one byte long, except (by default) newline. If - the PCRE_DOTALL option is set, dots match newlines as well. The han- - dling of dot is entirely independent of the handling of circumflex and - dollar, the only relationship being that they both involve newline - characters. Dot has no special meaning in a character class. - - -MATCHING A SINGLE BYTE - - Outside a character class, the escape sequence \C matches any one byte, - both in and out of UTF-8 mode. Unlike a dot, it can match a newline. - The feature is provided in Perl in order to match individual bytes in - UTF-8 mode. Because it breaks up UTF-8 characters into individual - bytes, what remains in the string may be a malformed UTF-8 string. For - this reason, the \C escape sequence is best avoided. - - PCRE does not allow \C to appear in lookbehind assertions (described - below), because in UTF-8 mode this would make it impossible to calcu- - late the length of the lookbehind. - - -SQUARE BRACKETS AND CHARACTER CLASSES - - An opening square bracket introduces a character class, terminated by a - closing square bracket. A closing square bracket on its own is not spe- - cial. If a closing square bracket is required as a member of the class, - it should be the first data character in the class (after an initial - circumflex, if present) or escaped with a backslash. - - A character class matches a single character in the subject. In UTF-8 - mode, the character may occupy more than one byte. A matched character - must be in the set of characters defined by the class, unless the first - character in the class definition is a circumflex, in which case the - subject character must not be in the set defined by the class. If a - circumflex is actually required as a member of the class, ensure it is - not the first character, or escape it with a backslash. - - For example, the character class [aeiou] matches any lower case vowel, - while [^aeiou] matches any character that is not a lower case vowel. - Note that a circumflex is just a convenient notation for specifying the - characters that are in the class by enumerating those that are not. A - class that starts with a circumflex is not an assertion: it still con- - sumes a character from the subject string, and therefore it fails if - the current pointer is at the end of the string. - - In UTF-8 mode, characters with values greater than 255 can be included - in a class as a literal string of bytes, or by using the \x{ escaping - mechanism. - - When caseless matching is set, any letters in a class represent both - their upper case and lower case versions, so for example, a caseless - [aeiou] matches "A" as well as "a", and a caseless [^aeiou] does not - match "A", whereas a caseful version would. When running in UTF-8 mode, - PCRE supports the concept of case for characters with values greater - than 128 only when it is compiled with Unicode property support. - - The newline character is never treated in any special way in character - classes, whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE - options is. A class such as [^a] will always match a newline. - - The minus (hyphen) character can be used to specify a range of charac- - ters in a character class. For example, [d-m] matches any letter - between d and m, inclusive. If a minus character is required in a - class, it must be escaped with a backslash or appear in a position - where it cannot be interpreted as indicating a range, typically as the - first or last character in the class. - - It is not possible to have the literal character "]" as the end charac- - ter of a range. A pattern such as [W-]46] is interpreted as a class of - two characters ("W" and "-") followed by a literal string "46]", so it - would match "W46]" or "-46]". However, if the "]" is escaped with a - backslash it is interpreted as the end of range, so [W-\]46] is inter- - preted as a class containing a range followed by two other characters. - The octal or hexadecimal representation of "]" can also be used to end - a range. - - Ranges operate in the collating sequence of character values. They can - also be used for characters specified numerically, for example - [\000-\037]. In UTF-8 mode, ranges can include characters whose values - are greater than 255, for example [\x{100}-\x{2ff}]. - - If a range that includes letters is used when caseless matching is set, - it matches the letters in either case. For example, [W-c] is equivalent - to [][\\^_`wxyzabc], matched caselessly, and in non-UTF-8 mode, if - character tables for the "fr_FR" locale are in use, [\xc8-\xcb] matches - accented E characters in both cases. In UTF-8 mode, PCRE supports the - concept of case for characters with values greater than 128 only when - it is compiled with Unicode property support. - - The character types \d, \D, \p, \P, \s, \S, \w, and \W may also appear - in a character class, and add the characters that they match to the - class. For example, [\dABCDEF] matches any hexadecimal digit. A circum- - flex can conveniently be used with the upper case character types to - specify a more restricted set of characters than the matching lower - case type. For example, the class [^\W_] matches any letter or digit, - but not underscore. - - The only metacharacters that are recognized in character classes are - backslash, hyphen (only where it can be interpreted as specifying a - range), circumflex (only at the start), opening square bracket (only - when it can be interpreted as introducing a POSIX class name - see the - next section), and the terminating closing square bracket. However, - escaping other non-alphanumeric characters does no harm. - - -POSIX CHARACTER CLASSES - - Perl supports the POSIX notation for character classes. This uses names - enclosed by [: and :] within the enclosing square brackets. PCRE also - supports this notation. For example, - - [01[:alpha:]%] - - matches "0", "1", any alphabetic character, or "%". The supported class - names are - - alnum letters and digits - alpha letters - ascii character codes 0 - 127 - blank space or tab only - cntrl control characters - digit decimal digits (same as \d) - graph printing characters, excluding space - lower lower case letters - print printing characters, including space - punct printing characters, excluding letters and digits - space white space (not quite the same as \s) - upper upper case letters - word "word" characters (same as \w) - xdigit hexadecimal digits - - The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), - and space (32). Notice that this list includes the VT character (code - 11). This makes "space" different to \s, which does not include VT (for - Perl compatibility). - - The name "word" is a Perl extension, and "blank" is a GNU extension - from Perl 5.8. Another Perl extension is negation, which is indicated - by a ^ character after the colon. For example, - - [12[:^digit:]] - - matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the - POSIX syntax [.ch.] and [=ch=] where "ch" is a "collating element", but - these are not supported, and an error is given if they are encountered. - - In UTF-8 mode, characters with values greater than 128 do not match any - of the POSIX character classes. - - -VERTICAL BAR - - Vertical bar characters are used to separate alternative patterns. For - example, the pattern - - gilbert|sullivan - - matches either "gilbert" or "sullivan". Any number of alternatives may - appear, and an empty alternative is permitted (matching the empty - string). The matching process tries each alternative in turn, from - left to right, and the first one that succeeds is used. If the alterna- - tives are within a subpattern (defined below), "succeeds" means match- - ing the rest of the main pattern as well as the alternative in the sub- - pattern. - - -INTERNAL OPTION SETTING - - The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and - PCRE_EXTENDED options can be changed from within the pattern by a - sequence of Perl option letters enclosed between "(?" and ")". The - option letters are - - i for PCRE_CASELESS - m for PCRE_MULTILINE - s for PCRE_DOTALL - x for PCRE_EXTENDED - - For example, (?im) sets caseless, multiline matching. It is also possi- - ble to unset these options by preceding the letter with a hyphen, and a - combined setting and unsetting such as (?im-sx), which sets PCRE_CASE- - LESS and PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, - is also permitted. If a letter appears both before and after the - hyphen, the option is unset. - - When an option change occurs at top level (that is, not inside subpat- - tern parentheses), the change applies to the remainder of the pattern - that follows. If the change is placed right at the start of a pattern, - PCRE extracts it into the global options (and it will therefore show up - in data extracted by the pcre_fullinfo() function). - - An option change within a subpattern affects only that part of the cur- - rent pattern that follows it, so - - (a(?i)b)c - - matches abc and aBc and no other strings (assuming PCRE_CASELESS is not - used). By this means, options can be made to have different settings - in different parts of the pattern. Any changes made in one alternative - do carry on into subsequent branches within the same subpattern. For - example, - - (a(?i)b|c) - - matches "ab", "aB", "c", and "C", even though when matching "C" the - first branch is abandoned before the option setting. This is because - the effects of option settings happen at compile time. There would be - some very weird behaviour otherwise. - - The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed - in the same way as the Perl-compatible options by using the characters - U and X respectively. The (?X) flag setting is special in that it must - always occur earlier in the pattern than any of the additional features - it turns on, even when it is at top level. It is best to put it at the - start. - - -SUBPATTERNS - - Subpatterns are delimited by parentheses (round brackets), which can be - nested. Turning part of a pattern into a subpattern does two things: - - 1. It localizes a set of alternatives. For example, the pattern - - cat(aract|erpillar|) - - matches one of the words "cat", "cataract", or "caterpillar". Without - the parentheses, it would match "cataract", "erpillar" or the empty - string. - - 2. It sets up the subpattern as a capturing subpattern. This means - that, when the whole pattern matches, that portion of the subject - string that matched the subpattern is passed back to the caller via the - ovector argument of pcre_exec(). Opening parentheses are counted from - left to right (starting from 1) to obtain numbers for the capturing - subpatterns. - - For example, if the string "the red king" is matched against the pat- - tern - - the ((red|white) (king|queen)) - - the captured substrings are "red king", "red", and "king", and are num- - bered 1, 2, and 3, respectively. - - The fact that plain parentheses fulfil two functions is not always - helpful. There are often times when a grouping subpattern is required - without a capturing requirement. If an opening parenthesis is followed - by a question mark and a colon, the subpattern does not do any captur- - ing, and is not counted when computing the number of any subsequent - capturing subpatterns. For example, if the string "the white queen" is - matched against the pattern - - the ((?:red|white) (king|queen)) - - the captured substrings are "white queen" and "queen", and are numbered - 1 and 2. The maximum number of capturing subpatterns is 65535, and the - maximum depth of nesting of all subpatterns, both capturing and non- - capturing, is 200. - - As a convenient shorthand, if any option settings are required at the - start of a non-capturing subpattern, the option letters may appear - between the "?" and the ":". Thus the two patterns - - (?i:saturday|sunday) - (?:(?i)saturday|sunday) - - match exactly the same set of strings. Because alternative branches are - tried from left to right, and options are not reset until the end of - the subpattern is reached, an option setting in one branch does affect - subsequent branches, so the above patterns match "SUNDAY" as well as - "Saturday". - - -NAMED SUBPATTERNS - - Identifying capturing parentheses by number is simple, but it can be - very hard to keep track of the numbers in complicated regular expres- - sions. Furthermore, if an expression is modified, the numbers may - change. To help with this difficulty, PCRE supports the naming of sub- - patterns, something that Perl does not provide. The Python syntax - (?P...) is used. Names consist of alphanumeric characters and - underscores, and must be unique within a pattern. - - Named capturing parentheses are still allocated numbers as well as - names. The PCRE API provides function calls for extracting the name-to- - number translation table from a compiled pattern. There is also a con- - venience function for extracting a captured substring by name. For fur- - ther details see the pcreapi documentation. - - -REPETITION - - Repetition is specified by quantifiers, which can follow any of the - following items: - - a literal data character - the . metacharacter - the \C escape sequence - the \X escape sequence (in UTF-8 mode with Unicode properties) - an escape such as \d that matches a single character - a character class - a back reference (see next section) - a parenthesized subpattern (unless it is an assertion) - - The general repetition quantifier specifies a minimum and maximum num- - ber of permitted matches, by giving the two numbers in curly brackets - (braces), separated by a comma. The numbers must be less than 65536, - and the first must be less than or equal to the second. For example: - - z{2,4} - - matches "zz", "zzz", or "zzzz". A closing brace on its own is not a - special character. If the second number is omitted, but the comma is - present, there is no upper limit; if the second number and the comma - are both omitted, the quantifier specifies an exact number of required - matches. Thus - - [aeiou]{3,} - - matches at least 3 successive vowels, but may match many more, while - - \d{8} - - matches exactly 8 digits. An opening curly bracket that appears in a - position where a quantifier is not allowed, or one that does not match - the syntax of a quantifier, is taken as a literal character. For exam- - ple, {,6} is not a quantifier, but a literal string of four characters. - - In UTF-8 mode, quantifiers apply to UTF-8 characters rather than to - individual bytes. Thus, for example, \x{100}{2} matches two UTF-8 char- - acters, each of which is represented by a two-byte sequence. Similarly, - when Unicode property support is available, \X{3} matches three Unicode - extended sequences, each of which may be several bytes long (and they - may be of different lengths). - - The quantifier {0} is permitted, causing the expression to behave as if - the previous item and the quantifier were not present. - - For convenience (and historical compatibility) the three most common - quantifiers have single-character abbreviations: - - * is equivalent to {0,} - + is equivalent to {1,} - ? is equivalent to {0,1} - - It is possible to construct infinite loops by following a subpattern - that can match no characters with a quantifier that has no upper limit, - for example: - - (a?)* - - Earlier versions of Perl and PCRE used to give an error at compile time - for such patterns. However, because there are cases where this can be - useful, such patterns are now accepted, but if any repetition of the - subpattern does in fact match no characters, the loop is forcibly bro- - ken. - - By default, the quantifiers are "greedy", that is, they match as much - as possible (up to the maximum number of permitted times), without - causing the rest of the pattern to fail. The classic example of where - this gives problems is in trying to match comments in C programs. These - appear between /* and */ and within the comment, individual * and / - characters may appear. An attempt to match C comments by applying the - pattern - - /\*.*\*/ - - to the string - - /* first comment */ not comment /* second comment */ - - fails, because it matches the entire string owing to the greediness of - the .* item. - - However, if a quantifier is followed by a question mark, it ceases to - be greedy, and instead matches the minimum number of times possible, so - the pattern - - /\*.*?\*/ - - does the right thing with the C comments. The meaning of the various - quantifiers is not otherwise changed, just the preferred number of - matches. Do not confuse this use of question mark with its use as a - quantifier in its own right. Because it has two uses, it can sometimes - appear doubled, as in - - \d??\d - - which matches one digit by preference, but can match two if that is the - only way the rest of the pattern matches. - - If the PCRE_UNGREEDY option is set (an option which is not available in - Perl), the quantifiers are not greedy by default, but individual ones - can be made greedy by following them with a question mark. In other - words, it inverts the default behaviour. - - When a parenthesized subpattern is quantified with a minimum repeat - count that is greater than 1 or with a limited maximum, more memory is - required for the compiled pattern, in proportion to the size of the - minimum or maximum. - - If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equiv- - alent to Perl's /s) is set, thus allowing the . to match newlines, the - pattern is implicitly anchored, because whatever follows will be tried - against every character position in the subject string, so there is no - point in retrying the overall match at any position after the first. - PCRE normally treats such a pattern as though it were preceded by \A. - - In cases where it is known that the subject string contains no new- - lines, it is worth setting PCRE_DOTALL in order to obtain this opti- - mization, or alternatively using ^ to indicate anchoring explicitly. - - However, there is one situation where the optimization cannot be used. - When .* is inside capturing parentheses that are the subject of a - backreference elsewhere in the pattern, a match at the start may fail, - and a later one succeed. Consider, for example: - - (.*)abc\1 - - If the subject is "xyz123abc123" the match point is the fourth charac- - ter. For this reason, such a pattern is not implicitly anchored. - - When a capturing subpattern is repeated, the value captured is the sub- - string that matched the final iteration. For example, after - - (tweedle[dume]{3}\s*)+ - - has matched "tweedledum tweedledee" the value of the captured substring - is "tweedledee". However, if there are nested capturing subpatterns, - the corresponding captured values may have been set in previous itera- - tions. For example, after - - /(a|(b))+/ - - matches "aba" the value of the second captured substring is "b". - - -ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS - - With both maximizing and minimizing repetition, failure of what follows - normally causes the repeated item to be re-evaluated to see if a dif- - ferent number of repeats allows the rest of the pattern to match. Some- - times it is useful to prevent this, either to change the nature of the - match, or to cause it fail earlier than it otherwise might, when the - author of the pattern knows there is no point in carrying on. - - Consider, for example, the pattern \d+foo when applied to the subject - line - - 123456bar - - After matching all 6 digits and then failing to match "foo", the normal - action of the matcher is to try again with only 5 digits matching the - \d+ item, and then with 4, and so on, before ultimately failing. - "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides - the means for specifying that once a subpattern has matched, it is not - to be re-evaluated in this way. - - If we use atomic grouping for the previous example, the matcher would - give up immediately on failing to match "foo" the first time. The nota- - tion is a kind of special parenthesis, starting with (?> as in this - example: - - (?>\d+)foo - - This kind of parenthesis "locks up" the part of the pattern it con- - tains once it has matched, and a failure further into the pattern is - prevented from backtracking into it. Backtracking past it to previous - items, however, works as normal. - - An alternative description is that a subpattern of this type matches - the string of characters that an identical standalone pattern would - match, if anchored at the current point in the subject string. - - Atomic grouping subpatterns are not capturing subpatterns. Simple cases - such as the above example can be thought of as a maximizing repeat that - must swallow everything it can. So, while both \d+ and \d+? are pre- - pared to adjust the number of digits they match in order to make the - rest of the pattern match, (?>\d+) can only match an entire sequence of - digits. - - Atomic groups in general can of course contain arbitrarily complicated - subpatterns, and can be nested. However, when the subpattern for an - atomic group is just a single repeated item, as in the example above, a - simpler notation, called a "possessive quantifier" can be used. This - consists of an additional + character following a quantifier. Using - this notation, the previous example can be rewritten as - - \d++foo - - Possessive quantifiers are always greedy; the setting of the - PCRE_UNGREEDY option is ignored. They are a convenient notation for the - simpler forms of atomic group. However, there is no difference in the - meaning or processing of a possessive quantifier and the equivalent - atomic group. - - The possessive quantifier syntax is an extension to the Perl syntax. It - originates in Sun's Java package. - - When a pattern contains an unlimited repeat inside a subpattern that - can itself be repeated an unlimited number of times, the use of an - atomic group is the only way to avoid some failing matches taking a - very long time indeed. The pattern - - (\D+|<\d+>)*[!?] - - matches an unlimited number of substrings that either consist of non- - digits, or digits enclosed in <>, followed by either ! or ?. When it - matches, it runs quickly. However, if it is applied to - - aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa - - it takes a long time before reporting failure. This is because the - string can be divided between the internal \D+ repeat and the external - * repeat in a large number of ways, and all have to be tried. (The - example uses [!?] rather than a single character at the end, because - both PCRE and Perl have an optimization that allows for fast failure - when a single character is used. They remember the last single charac- - ter that is required for a match, and fail early if it is not present - in the string.) If the pattern is changed so that it uses an atomic - group, like this: - - ((?>\D+)|<\d+>)*[!?] - - sequences of non-digits cannot be broken, and failure happens quickly. - - -BACK REFERENCES - - Outside a character class, a backslash followed by a digit greater than - 0 (and possibly further digits) is a back reference to a capturing sub- - pattern earlier (that is, to its left) in the pattern, provided there - have been that many previous capturing left parentheses. - - However, if the decimal number following the backslash is less than 10, - it is always taken as a back reference, and causes an error only if - there are not that many capturing left parentheses in the entire pat- - tern. In other words, the parentheses that are referenced need not be - to the left of the reference for numbers less than 10. See the subsec- - tion entitled "Non-printing characters" above for further details of - the handling of digits following a backslash. - - A back reference matches whatever actually matched the capturing sub- - pattern in the current subject string, rather than anything matching - the subpattern itself (see "Subpatterns as subroutines" below for a way - of doing that). So the pattern - - (sens|respons)e and \1ibility - - matches "sense and sensibility" and "response and responsibility", but - not "sense and responsibility". If caseful matching is in force at the - time of the back reference, the case of letters is relevant. For exam- - ple, - - ((?i)rah)\s+\1 - - matches "rah rah" and "RAH RAH", but not "RAH rah", even though the - original capturing subpattern is matched caselessly. - - Back references to named subpatterns use the Python syntax (?P=name). - We could rewrite the above example as follows: - - (?(?i)rah)\s+(?P=p1) - - There may be more than one back reference to the same subpattern. If a - subpattern has not actually been used in a particular match, any back - references to it always fail. For example, the pattern - - (a|(bc))\2 - - always fails if it starts to match "a" rather than "bc". Because there - may be many capturing parentheses in a pattern, all digits following - the backslash are taken as part of a potential back reference number. - If the pattern continues with a digit character, some delimiter must be - used to terminate the back reference. If the PCRE_EXTENDED option is - set, this can be whitespace. Otherwise an empty comment (see "Com- - ments" below) can be used. - - A back reference that occurs inside the parentheses to which it refers - fails when the subpattern is first used, so, for example, (a\1) never - matches. However, such references can be useful inside repeated sub- - patterns. For example, the pattern - - (a|b\1)+ - - matches any number of "a"s and also "aba", "ababbaa" etc. At each iter- - ation of the subpattern, the back reference matches the character - string corresponding to the previous iteration. In order for this to - work, the pattern must be such that the first iteration does not need - to match the back reference. This can be done using alternation, as in - the example above, or by a quantifier with a minimum of zero. - - -ASSERTIONS - - An assertion is a test on the characters following or preceding the - current matching point that does not actually consume any characters. - The simple assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are - described above. - - More complicated assertions are coded as subpatterns. There are two - kinds: those that look ahead of the current position in the subject - string, and those that look behind it. An assertion subpattern is - matched in the normal way, except that it does not cause the current - matching position to be changed. - - Assertion subpatterns are not capturing subpatterns, and may not be - repeated, because it makes no sense to assert the same thing several - times. If any kind of assertion contains capturing subpatterns within - it, these are counted for the purposes of numbering the capturing sub- - patterns in the whole pattern. However, substring capturing is carried - out only for positive assertions, because it does not make sense for - negative assertions. - - Lookahead assertions - - Lookahead assertions start with (?= for positive assertions and (?! for - negative assertions. For example, - - \w+(?=;) - - matches a word followed by a semicolon, but does not include the semi- - colon in the match, and - - foo(?!bar) - - matches any occurrence of "foo" that is not followed by "bar". Note - that the apparently similar pattern - - (?!foo)bar - - does not find an occurrence of "bar" that is preceded by something - other than "foo"; it finds any occurrence of "bar" whatsoever, because - the assertion (?!foo) is always true when the next three characters are - "bar". A lookbehind assertion is needed to achieve the other effect. - - If you want to force a matching failure at some point in a pattern, the - most convenient way to do it is with (?!) because an empty string - always matches, so an assertion that requires there not to be an empty - string must always fail. - - Lookbehind assertions - - Lookbehind assertions start with (?<= for positive assertions and (?.*)(?<=abcd) - - or, equivalently, using the possessive quantifier syntax, - - ^.*+(?<=abcd) - - there can be no backtracking for the .* item; it can match only the - entire string. The subsequent lookbehind assertion does a single test - on the last four characters. If it fails, the match fails immediately. - For long strings, this approach makes a significant difference to the - processing time. - - Using multiple assertions - - Several assertions (of any sort) may occur in succession. For example, - - (?<=\d{3})(?[^()]+) | (?p{$re}) )* \)}x; - - The (?p{...}) item interpolates Perl code at run time, and in this case - refers recursively to the pattern in which it appears. Obviously, PCRE - cannot support the interpolation of Perl code. Instead, it supports - some special syntax for recursion of the entire pattern, and also for - individual subpattern recursion. - - The special item that consists of (? followed by a number greater than - zero and a closing parenthesis is a recursive call of the subpattern of - the given number, provided that it occurs inside that subpattern. (If - not, it is a "subroutine" call, which is described in the next sec- - tion.) The special item (?R) is a recursive call of the entire regular - expression. - - For example, this PCRE pattern solves the nested parentheses problem - (assume the PCRE_EXTENDED option is set so that white space is - ignored): - - \( ( (?>[^()]+) | (?R) )* \) - - First it matches an opening parenthesis. Then it matches any number of - substrings which can either be a sequence of non-parentheses, or a - recursive match of the pattern itself (that is a correctly parenthe- - sized substring). Finally there is a closing parenthesis. - - If this were part of a larger pattern, you would not want to recurse - the entire pattern, so instead you could use this: - - ( \( ( (?>[^()]+) | (?1) )* \) ) - - We have put the pattern into parentheses, and caused the recursion to - refer to them instead of the whole pattern. In a larger pattern, keep- - ing track of parenthesis numbers can be tricky. It may be more conve- - nient to use named parentheses instead. For this, PCRE uses (?P>name), - which is an extension to the Python syntax that PCRE uses for named - parentheses (Perl does not provide named parentheses). We could rewrite - the above example as follows: - - (?P \( ( (?>[^()]+) | (?P>pn) )* \) ) - - This particular example pattern contains nested unlimited repeats, and - so the use of atomic grouping for matching strings of non-parentheses - is important when applying the pattern to strings that do not match. - For example, when this pattern is applied to - - (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa() - - it yields "no match" quickly. However, if atomic grouping is not used, - the match runs for a very long time indeed because there are so many - different ways the + and * repeats can carve up the subject, and all - have to be tested before failure can be reported. - - At the end of a match, the values set for any capturing subpatterns are - those from the outermost level of the recursion at which the subpattern - value is set. If you want to obtain intermediate values, a callout - function can be used (see the next section and the pcrecallout documen- - tation). If the pattern above is matched against - - (ab(cd)ef) - - the value for the capturing parentheses is "ef", which is the last - value taken on at the top level. If additional parentheses are added, - giving - - \( ( ( (?>[^()]+) | (?R) )* ) \) - ^ ^ - ^ ^ - - the string they capture is "ab(cd)ef", the contents of the top level - parentheses. If there are more than 15 capturing parentheses in a pat- - tern, PCRE has to obtain extra memory to store data during a recursion, - which it does by using pcre_malloc, freeing it via pcre_free after- - wards. If no memory can be obtained, the match fails with the - PCRE_ERROR_NOMEMORY error. - - Do not confuse the (?R) item with the condition (R), which tests for - recursion. Consider this pattern, which matches text in angle brack- - ets, allowing for arbitrary nesting. Only digits are allowed in nested - brackets (that is, when recursing), whereas any characters are permit- - ted at the outer level. - - < (?: (?(R) \d++ | [^<>]*+) | (?R)) * > - - In this pattern, (?(R) is the start of a conditional subpattern, with - two different alternatives for the recursive and non-recursive cases. - The (?R) item is the actual recursive call. - - -SUBPATTERNS AS SUBROUTINES - - If the syntax for a recursive subpattern reference (either by number or - by name) is used outside the parentheses to which it refers, it oper- - ates like a subroutine in a programming language. An earlier example - pointed out that the pattern - - (sens|respons)e and \1ibility - - matches "sense and sensibility" and "response and responsibility", but - not "sense and responsibility". If instead the pattern - - (sens|respons)e and (?1)ibility - - is used, it does match "sense and responsibility" as well as the other - two strings. Such references must, however, follow the subpattern to - which they refer. - - -CALLOUTS - - Perl has a feature whereby using the sequence (?{...}) causes arbitrary - Perl code to be obeyed in the middle of matching a regular expression. - This makes it possible, amongst other things, to extract different sub- - strings that match the same pair of parentheses when there is a repeti- - tion. - - PCRE provides a similar feature, but of course it cannot obey arbitrary - Perl code. The feature is called "callout". The caller of PCRE provides - an external function by putting its entry point in the global variable - pcre_callout. By default, this variable contains NULL, which disables - all calling out. - - Within a regular expression, (?C) indicates the points at which the - external function is to be called. If you want to identify different - callout points, you can put a number less than 256 after the letter C. - The default value is zero. For example, this pattern has two callout - points: - - (?C1)abc(?C2)def - - If the PCRE_AUTO_CALLOUT flag is passed to pcre_compile(), callouts are - automatically installed before each item in the pattern. They are all - numbered 255. - - During matching, when PCRE reaches a callout point (and pcre_callout is - set), the external function is called. It is provided with the number - of the callout, the position in the pattern, and, optionally, one item - of data originally supplied by the caller of pcre_exec(). The callout - function may cause matching to proceed, to backtrack, or to fail alto- - gether. A complete description of the interface to the callout function - is given in the pcrecallout documentation. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PARTIAL MATCHING IN PCRE - - In normal use of PCRE, if the subject string that is passed to - pcre_exec() matches as far as it goes, but is too short to match the - entire pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances - where it might be helpful to distinguish this case from other cases in - which there is no match. - - Consider, for example, an application where a human is required to type - in data for a field with specific formatting requirements. An example - might be a date in the form ddmmmyy, defined by this pattern: - - ^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$ - - If the application sees the user's keystrokes one by one, and can check - that what has been typed so far is potentially valid, it is able to - raise an error as soon as a mistake is made, possibly beeping and not - reflecting the character that has been typed. This immediate feedback - is likely to be a better user interface than a check that is delayed - until the entire string has been entered. - - PCRE supports the concept of partial matching by means of the PCRE_PAR- - TIAL option, which can be set when calling pcre_exec(). When this is - done, the return code PCRE_ERROR_NOMATCH is converted into - PCRE_ERROR_PARTIAL if at any time during the matching process the - entire subject string matched part of the pattern. No captured data is - set when this occurs. - - Using PCRE_PARTIAL disables one of PCRE's optimizations. PCRE remembers - the last literal byte in a pattern, and abandons matching immediately - if such a byte is not present in the subject string. This optimization - cannot be used for a subject string that might match only partially. - - -RESTRICTED PATTERNS FOR PCRE_PARTIAL - - Because of the way certain internal optimizations are implemented in - PCRE, the PCRE_PARTIAL option cannot be used with all patterns. - Repeated single characters such as - - a{2,4} - - and repeated single metasequences such as - - \d+ - - are not permitted if the maximum number of occurrences is greater than - one. Optional items such as \d? (where the maximum is one) are permit- - ted. Quantifiers with any values are permitted after parentheses, so - the invalid examples above can be coded thus: - - (a){2,4} - (\d)+ - - These constructions run more slowly, but for the kinds of application - that are envisaged for this facility, this is not felt to be a major - restriction. - - If PCRE_PARTIAL is set for a pattern that does not conform to the - restrictions, pcre_exec() returns the error code PCRE_ERROR_BADPARTIAL - (-13). - - -EXAMPLE OF PARTIAL MATCHING USING PCRETEST - - If the escape sequence \P is present in a pcretest data line, the - PCRE_PARTIAL flag is used for the match. Here is a run of pcretest that - uses the date example quoted above: - - re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ - data> 25jun04P - 0: 25jun04 - 1: jun - data> 25dec3P - Partial match - data> 3juP - Partial match - data> 3jujP - No match - data> jP - No match - - The first data string is matched completely, so pcretest shows the - matched substrings. The remaining four strings do not match the com- - plete pattern, but the first two are partial matches. - -Last updated: 08 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -SAVING AND RE-USING PRECOMPILED PCRE PATTERNS - - If you are running an application that uses a large number of regular - expression patterns, it may be useful to store them in a precompiled - form instead of having to compile them every time the application is - run. If you are not using any private character tables (see the - pcre_maketables() documentation), this is relatively straightforward. - If you are using private tables, it is a little bit more complicated. - - If you save compiled patterns to a file, you can copy them to a differ- - ent host and run them there. This works even if the new host has the - opposite endianness to the one on which the patterns were compiled. - There may be a small performance penalty, but it should be insignifi- - cant. - - -SAVING A COMPILED PATTERN - The value returned by pcre_compile() points to a single block of memory - that holds the compiled pattern and associated data. You can find the - length of this block in bytes by calling pcre_fullinfo() with an argu- - ment of PCRE_INFO_SIZE. You can then save the data in any appropriate - manner. Here is sample code that compiles a pattern and writes it to a - file. It assumes that the variable fd refers to a file that is open for - output: - - int erroroffset, rc, size; - char *error; - pcre *re; - - re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL); - if (re == NULL) { ... handle errors ... } - rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size); - if (rc < 0) { ... handle errors ... } - rc = fwrite(re, 1, size, fd); - if (rc != size) { ... handle errors ... } - - In this example, the bytes that comprise the compiled pattern are - copied exactly. Note that this is binary data that may contain any of - the 256 possible byte values. On systems that make a distinction - between binary and non-binary data, be sure that the file is opened for - binary output. - - If you want to write more than one pattern to a file, you will have to - devise a way of separating them. For binary data, preceding each pat- - tern with its length is probably the most straightforward approach. - Another possibility is to write out the data in hexadecimal instead of - binary, one pattern to a line. - - Saving compiled patterns in a file is only one possible way of storing - them for later use. They could equally well be saved in a database, or - in the memory of some daemon process that passes them via sockets to - the processes that want them. - - If the pattern has been studied, it is also possible to save the study - data in a similar way to the compiled pattern itself. When studying - generates additional information, pcre_study() returns a pointer to a - pcre_extra data block. Its format is defined in the section on matching - a pattern in the pcreapi documentation. The study_data field points to - the binary study data, and this is what you must save (not the - pcre_extra block itself). The length of the study data can be obtained - by calling pcre_fullinfo() with an argument of PCRE_INFO_STUDYSIZE. - Remember to check that pcre_study() did return a non-NULL value before - trying to save the study data. - - -RE-USING A PRECOMPILED PATTERN - - Re-using a precompiled pattern is straightforward. Having reloaded it - into main memory, you pass its pointer to pcre_exec() in the usual way. - This should work even on another host, and even if that host has the - opposite endianness to the one where the pattern was compiled. - - However, if you passed a pointer to custom character tables when the - pattern was compiled (the tableptr argument of pcre_compile()), you - must now pass a similar pointer to pcre_exec(), because the value saved - with the compiled pattern will obviously be nonsense. A field in a - pcre_extra() block is used to pass this data, as described in the sec- - tion on matching a pattern in the pcreapi documentation. - - If you did not provide custom character tables when the pattern was - compiled, the pointer in the compiled pattern is NULL, which causes - pcre_exec() to use PCRE's internal tables. Thus, you do not need to - take any special action at run time in this case. - - If you saved study data with the compiled pattern, you need to create - your own pcre_extra data block and set the study_data field to point to - the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA - bit in the flags field to indicate that study data is present. Then - pass the pcre_extra block to pcre_exec() in the usual way. - - -COMPATIBILITY WITH DIFFERENT PCRE RELEASES - - The layout of the control block that is at the start of the data that - makes up a compiled pattern was changed for release 5.0. If you have - any saved patterns that were compiled with previous releases (not a - facility that was previously advertised), you will have to recompile - them for release 5.0. However, from now on, it should be possible to - make changes in a compabible manner. - -Last updated: 10 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PCRE PERFORMANCE - - Certain items that may appear in regular expression patterns are more - efficient than others. It is more efficient to use a character class - like [aeiou] than a set of alternatives such as (a|e|i|o|u). In gen- - eral, the simplest construction that provides the required behaviour is - usually the most efficient. Jeffrey Friedl's book contains a lot of - useful general discussion about optimizing regular expressions for - efficient performance. This document contains a few observations about - PCRE. - - Using Unicode character properties (the \p, \P, and \X escapes) is - slow, because PCRE has to scan a structure that contains data for over - fifteen thousand characters whenever it needs a character's property. - If you can find an alternative pattern that does not use character - properties, it will probably be faster. - - When a pattern begins with .* not in parentheses, or in parentheses - that are not the subject of a backreference, and the PCRE_DOTALL option - is set, the pattern is implicitly anchored by PCRE, since it can match - only at the start of a subject string. However, if PCRE_DOTALL is not - set, PCRE cannot make this optimization, because the . metacharacter - does not then match a newline, and if the subject string contains new- - lines, the pattern may match from the character immediately following - one of them instead of from the very start. For example, the pattern - - .*second - - matches the subject "first\nand second" (where \n stands for a newline - character), with the match starting at the seventh character. In order - to do this, PCRE has to retry the match starting after every newline in - the subject. - - If you are using such a pattern with subject strings that do not con- - tain newlines, the best performance is obtained by setting PCRE_DOTALL, - or starting the pattern with ^.* to indicate explicit anchoring. That - saves PCRE from having to scan along the subject looking for a newline - to restart at. - - Beware of patterns that contain nested indefinite repeats. These can - take a long time to run when applied to a string that does not match. - Consider the pattern fragment - - (a+)* - - This can match "aaaa" in 33 different ways, and this number increases - very rapidly as the string gets longer. (The * repeat can match 0, 1, - 2, 3, or 4 times, and for each of those cases other than 0, the + - repeats can match different numbers of times.) When the remainder of - the pattern is such that the entire match is going to fail, PCRE has in - principle to try every possible variation, and this can take an - extremely long time. - - An optimization catches some of the more simple cases such as - - (a+)*b - - where a literal character follows. Before embarking on the standard - matching procedure, PCRE checks that there is a "b" later in the - subject string, and if there is not, it fails the match immediately. - However, when there is no following literal this optimization cannot be - used. You can see the difference by comparing the behaviour of - - (a+)*\d - - with the pattern above. The former gives a failure almost instantly - when applied to a whole line of "a" characters, whereas the latter - takes an appreciable time with strings longer than about 20 characters. - - In many cases, the solution to this kind of performance issue is to use - an atomic group or a possessive quantifier. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions. - -SYNOPSIS OF POSIX API - - #include - - int regcomp(regex_t *preg, const char *pattern, - int cflags); - - int regexec(regex_t *preg, const char *string, - size_t nmatch, regmatch_t pmatch[], int eflags); - - size_t regerror(int errcode, const regex_t *preg, - char *errbuf, size_t errbuf_size); - - void regfree(regex_t *preg); - - -DESCRIPTION - - This set of functions provides a POSIX-style API to the PCRE regular - expression package. See the pcreapi documentation for a description of - PCRE's native API, which contains additional functionality. - - The functions described here are just wrapper functions that ultimately - call the PCRE native API. Their prototypes are defined in the - pcreposix.h header file, and on Unix systems the library itself is - called pcreposix.a, so can be accessed by adding -lpcreposix to the - command for linking an application that uses them. Because the POSIX - functions call the native ones, it is also necessary to add -lpcre. - - I have implemented only those option bits that can be reasonably mapped - to PCRE native options. In addition, the options REG_EXTENDED and - REG_NOSUB are defined with the value zero. They have no effect, but - since programs that are written to the POSIX interface often use them, - this makes it easier to slot in PCRE as a replacement library. Other - POSIX options are not even defined. - - When PCRE is called via these functions, it is only the API that is - POSIX-like in style. The syntax and semantics of the regular expres- - sions themselves are still those of Perl, subject to the setting of - various PCRE options, as described below. "POSIX-like in style" means - that the API approximates to the POSIX definition; it is not fully - POSIX-compatible, and in multi-byte encoding domains it is probably - even less compatible. - - The header for these functions is supplied as pcreposix.h to avoid any - potential clash with other POSIX libraries. It can, of course, be - renamed or aliased as regex.h, which is the "correct" name. It provides - two structure types, regex_t for compiled internal forms, and reg- - match_t for returning captured substrings. It also defines some con- - stants whose names start with "REG_"; these are used for setting - options and identifying error codes. - - -COMPILING A PATTERN - - The function regcomp() is called to compile a pattern into an internal - form. The pattern is a C string terminated by a binary zero, and is - passed in the argument pattern. The preg argument is a pointer to a - regex_t structure that is used as a base for storing information about - the compiled expression. - - The argument cflags is either zero, or contains one or more of the bits - defined by the following macros: - - REG_ICASE - - The PCRE_CASELESS option is set when the expression is passed for com- - pilation to the native function. - - REG_NEWLINE - - The PCRE_MULTILINE option is set when the expression is passed for com- - pilation to the native function. Note that this does not mimic the - defined POSIX behaviour for REG_NEWLINE (see the following section). - - In the absence of these flags, no options are passed to the native - function. This means the the regex is compiled with PCRE default - semantics. In particular, the way it handles newline characters in the - subject string is the Perl way, not the POSIX way. Note that setting - PCRE_MULTILINE has only some of the effects specified for REG_NEWLINE. - It does not affect the way newlines are matched by . (they aren't) or - by a negative class such as [^a] (they are). - - The yield of regcomp() is zero on success, and non-zero otherwise. The - preg structure is filled in on success, and one member of the structure - is public: re_nsub contains the number of capturing subpatterns in the - regular expression. Various error codes are defined in the header file. - - -MATCHING NEWLINE CHARACTERS - - This area is not simple, because POSIX and Perl take different views of - things. It is not possible to get PCRE to obey POSIX semantics, but - then PCRE was never intended to be a POSIX engine. The following table - lists the different possibilities for matching newline characters in - PCRE: - - Default Change with - - . matches newline no PCRE_DOTALL - newline matches [^a] yes not changeable - $ matches \n at end yes PCRE_DOLLARENDONLY - $ matches \n in middle no PCRE_MULTILINE - ^ matches \n in middle no PCRE_MULTILINE - - This is the equivalent table for POSIX: - - Default Change with - - . matches newline yes REG_NEWLINE - newline matches [^a] yes REG_NEWLINE - $ matches \n at end no REG_NEWLINE - $ matches \n in middle no REG_NEWLINE - ^ matches \n in middle no REG_NEWLINE - - PCRE's behaviour is the same as Perl's, except that there is no equiva- - lent for PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is - no way to stop newline from matching [^a]. - - The default POSIX newline handling can be obtained by setting - PCRE_DOTALL and PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE - behave exactly as for the REG_NEWLINE action. - - -MATCHING A PATTERN - - The function regexec() is called to match a compiled pattern preg - against a given string, which is terminated by a zero byte, subject to - the options in eflags. These can be: - - REG_NOTBOL - - The PCRE_NOTBOL option is set when calling the underlying PCRE matching - function. - - REG_NOTEOL - - The PCRE_NOTEOL option is set when calling the underlying PCRE matching - function. - - The portion of the string that was matched, and also any captured sub- - strings, are returned via the pmatch argument, which points to an array - of nmatch structures of type regmatch_t, containing the members rm_so - and rm_eo. These contain the offset to the first character of each sub- - string and the offset to the first character after the end of each sub- - string, respectively. The 0th element of the vector relates to the - entire portion of string that was matched; subsequent elements relate - to the capturing subpatterns of the regular expression. Unused entries - in the array have both structure members set to -1. - - A successful match yields a zero return; various error codes are - defined in the header file, of which REG_NOMATCH is the "expected" - failure code. - - -ERROR MESSAGES - - The regerror() function maps a non-zero errorcode from either regcomp() - or regexec() to a printable message. If preg is not NULL, the error - should have arisen from the use of that structure. A message terminated - by a binary zero is placed in errbuf. The length of the message, - including the zero, is limited to errbuf_size. The yield of the func- - tion is the size of buffer needed to hold the whole message. - - -MEMORY USAGE - - Compiling a regular expression causes memory to be allocated and asso- - ciated with the preg structure. The function regfree() frees all such - memory, after which preg may no longer be used as a compiled expres- - sion. - - -AUTHOR - - Philip Hazel - University Computing Service, - Cambridge CB2 3QG, England. - -Last updated: 07 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - -PCRE(3) PCRE(3) - - - -NAME - PCRE - Perl-compatible regular expressions - -PCRE SAMPLE PROGRAM - - A simple, complete demonstration program, to get you started with using - PCRE, is supplied in the file pcredemo.c in the PCRE distribution. - - The program compiles the regular expression that is its first argument, - and matches it against the subject string in its second argument. No - PCRE options are set, and default character tables are used. If match- - ing succeeds, the program outputs the portion of the subject that - matched, together with the contents of any captured substrings. - - If the -g option is given on the command line, the program then goes on - to check for further matches of the same regular expression in the same - subject string. The logic is a little bit tricky because of the possi- - bility of matching an empty string. Comments in the code explain what - is going on. - - If PCRE is installed in the standard include and library directories - for your system, you should be able to compile the demonstration pro- - gram using this command: - - gcc -o pcredemo pcredemo.c -lpcre - - If PCRE is installed elsewhere, you may need to add additional options - to the command line. For example, on a Unix-like system that has PCRE - installed in /usr/local, you can compile the demonstration program - using a command like this: - - gcc -o pcredemo -I/usr/local/include pcredemo.c \ - -L/usr/local/lib -lpcre - - Once you have compiled the demonstration program, you can run simple - tests like this: - - ./pcredemo 'cat|dog' 'the cat sat on the mat' - ./pcredemo -g 'cat|dog' 'the dog sat on the cat' - - Note that there is a much more comprehensive test program, called - pcretest, which supports many more facilities for testing regular - expressions and the PCRE library. The pcredemo program is provided as a - simple coding example. - - On some operating systems (e.g. Solaris), when PCRE is not installed in - the standard library directory, you may get an error like this when you - try to run pcredemo: - - ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or - directory - - This is caused by the way shared library support works on those sys- - tems. You need to add - - -R/usr/local/lib - - (for example) to the compile command to get round this problem. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. ------------------------------------------------------------------------------ - diff --git a/srclib/pcre/doc/pcre_compile.3 b/srclib/pcre/doc/pcre_compile.3 deleted file mode 100644 index 37a5f2d936..0000000000 --- a/srclib/pcre/doc/pcre_compile.3 +++ /dev/null @@ -1,64 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP, -.ti +5n -.B const char **\fIerrptr\fP, int *\fIerroffset\fP, -.ti +5n -.B const unsigned char *\fItableptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This function compiles a regular expression into an internal form. Its -arguments are: -.sp - \fIpattern\fR A zero-terminated string containing the - regular expression to be compiled - \fIoptions\fR Zero or more option bits - \fIerrptr\fR Where to put an error message - \fIerroffset\fR Offset in pattern where error was found - \fItableptr\fR Pointer to character tables, or NULL to - use the built-in default -.sp -The option bits are: -.sp - PCRE_ANCHORED Force pattern anchoring - PCRE_AUTO_CALLOUT Compile automatic callouts - PCRE_CASELESS Do caseless matching - PCRE_DOLLAR_ENDONLY $ not to match newline at end - PCRE_DOTALL . matches anything including NL - PCRE_EXTENDED Ignore whitespace and # comments - PCRE_EXTRA PCRE extra features - (not much use currently) - PCRE_MULTILINE ^ and $ match newlines within data - PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren- - theses (named ones available) - PCRE_UNGREEDY Invert greediness of quantifiers - PCRE_UTF8 Run in UTF-8 mode - PCRE_NO_UTF8_CHECK Do not check the pattern for UTF-8 - validity (only relevant if - PCRE_UTF8 is set) -.sp -PCRE must be built with UTF-8 support in order to use PCRE_UTF8 and -PCRE_NO_UTF8_CHECK. -.P -The yield of the function is a pointer to a private data structure that -contains the compiled pattern, or NULL if an error was detected. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fR -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fR -.\" -page. diff --git a/srclib/pcre/doc/pcre_config.3 b/srclib/pcre/doc/pcre_config.3 deleted file mode 100644 index 1ba934435a..0000000000 --- a/srclib/pcre/doc/pcre_config.3 +++ /dev/null @@ -1,48 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP); -. -.SH DESCRIPTION -.rs -.sp -This function makes it possible for a client program to find out which optional -features are available in the version of the PCRE library it is using. Its -arguments are as follows: -.sp - \fIwhat\fR A code specifying what information is required - \fIwhere\fR Points to where to put the data -.sp -The available codes are: -.sp - PCRE_CONFIG_LINK_SIZE Internal link size: 2, 3, or 4 - PCRE_CONFIG_MATCH_LIMIT Internal resource limit - PCRE_CONFIG_NEWLINE Value of the newline character - PCRE_CONFIG_POSIX_MALLOC_THRESHOLD - Threshold of return slots, above - which \fBmalloc()\fR is used by - the POSIX API - PCRE_CONFIG_STACKRECURSE Recursion implementation (1=stack 0=heap) - PCRE_CONFIG_UTF8 Availability of UTF-8 support (1=yes 0=no) - PCRE_CONFIG_UNICODE_PROPERTIES - Availability of Unicode property support - (1=yes 0=no) -.sp -The function yields 0 on success or PCRE_ERROR_BADOPTION otherwise. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fR -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fR -.\" -page. diff --git a/srclib/pcre/doc/pcre_copy_named_substring.3 b/srclib/pcre/doc/pcre_copy_named_substring.3 deleted file mode 100644 index 92e47bee20..0000000000 --- a/srclib/pcre/doc/pcre_copy_named_substring.3 +++ /dev/null @@ -1,44 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_copy_named_substring(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, const char *\fIstringname\fP, -.ti +5n -.B char *\fIbuffer\fP, int \fIbuffersize\fP); -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for extracting a captured substring, identified -by name, into a given buffer. The arguments are: -.sp - \fIcode\fP Pattern that was successfully matched - \fIsubject\fP Subject that has been successfully matched - \fIovector\fP Offset vector that \fBpcre_exec()\fP used - \fIstringcount\fP Value returned by \fBpcre_exec()\fP - \fIstringname\fP Name of the required substring - \fIbuffer\fP Buffer to receive the string - \fIbuffersize\fP Size of buffer -.sp -The yield is the length of the substring, PCRE_ERROR_NOMEMORY if the buffer was -too small, or PCRE_ERROR_NOSUBSTRING if the string name is invalid. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_copy_substring.3 b/srclib/pcre/doc/pcre_copy_substring.3 deleted file mode 100644 index c467b502d1..0000000000 --- a/srclib/pcre/doc/pcre_copy_substring.3 +++ /dev/null @@ -1,41 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP, -.ti +5n -.B int \fIbuffersize\fP); -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for extracting a captured substring into a given -buffer. The arguments are: -.sp - \fIsubject\fP Subject that has been successfully matched - \fIovector\fP Offset vector that \fBpcre_exec()\fP used - \fIstringcount\fP Value returned by \fBpcre_exec()\fP - \fIstringnumber\fP Number of the required substring - \fIbuffer\fP Buffer to receive the string - \fIbuffersize\fP Size of buffer -.sp -The yield is the legnth of the string, PCRE_ERROR_NOMEMORY if the buffer was -too small, or PCRE_ERROR_NOSUBSTRING if the string number is invalid. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_exec.3 b/srclib/pcre/doc/pcre_exec.3 deleted file mode 100644 index 7e071a9be6..0000000000 --- a/srclib/pcre/doc/pcre_exec.3 +++ /dev/null @@ -1,67 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP," -.ti +5n -.B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP, -.ti +5n -.B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP); -. -.SH DESCRIPTION -.rs -.sp -This function matches a compiled regular expression against a given subject -string, and returns offsets to capturing subexpressions. Its arguments are: -.sp - \fIcode\fP Points to the compiled pattern - \fIextra\fP Points to an associated \fBpcre_extra\fP structure, - or is NULL - \fIsubject\fP Points to the subject string - \fIlength\fP Length of the subject string, in bytes - \fIstartoffset\fP Offset in bytes in the subject at which to - start matching - \fIoptions\fP Option bits - \fIovector\fP Points to a vector of ints for result offsets - \fIovecsize\fP Number of elements in the vector (a multiple of 3) -.sp -The options are: -.sp - PCRE_ANCHORED Match only at the first position - PCRE_NOTBOL Subject is not the beginning of a line - PCRE_NOTEOL Subject is not the end of a line - PCRE_NOTEMPTY An empty string is not a valid match - PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8 - validity (only relevant if PCRE_UTF8 - was set at compile time) - PCRE_PARTIAL Return PCRE_ERROR_PARTIAL for a partial match -.sp -There are restrictions on what may appear in a pattern when partial matching is -requested. -.P -A \fBpcre_extra\fP structure contains the following fields: -.sp - \fIflags\fP Bits indicating which fields are set - \fIstudy_data\fP Opaque data from \fBpcre_study()\fP - \fImatch_limit\fP Limit on internal recursion - \fIcallout_data\fP Opaque data passed back to callouts - \fItables\fP Points to character tables or is NULL -.sp -The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, -PCRE_EXTRA_CALLOUT_DATA, and PCRE_EXTRA_TABLES. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_free_substring.3 b/srclib/pcre/doc/pcre_free_substring.3 deleted file mode 100644 index 1aafd877bf..0000000000 --- a/srclib/pcre/doc/pcre_free_substring.3 +++ /dev/null @@ -1,28 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B void pcre_free_substring(const char *\fIstringptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for freeing the store obtained by a previous -call to \fBpcre_get_substring()\fP or \fBpcre_get_named_substring()\fP. Its -only argument is a pointer to the string. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_free_substring_list.3 b/srclib/pcre/doc/pcre_free_substring_list.3 deleted file mode 100644 index d68c3a10bb..0000000000 --- a/srclib/pcre/doc/pcre_free_substring_list.3 +++ /dev/null @@ -1,28 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B void pcre_free_substring_list(const char **\fIstringptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for freeing the store obtained by a previous -call to \fBpcre_get_substring_list()\fP. Its only argument is a pointer to the -list of string pointers. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_fullinfo.3 b/srclib/pcre/doc/pcre_fullinfo.3 deleted file mode 100644 index 4738127df0..0000000000 --- a/srclib/pcre/doc/pcre_fullinfo.3 +++ /dev/null @@ -1,59 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP," -.ti +5n -.B int \fIwhat\fP, void *\fIwhere\fP); -. -.SH DESCRIPTION -.rs -.sp -This function returns information about a compiled pattern. Its arguments are: -.sp - \fIcode\fP Compiled regular expression - \fIextra\fP Result of \fBpcre_study()\fP or NULL - \fIwhat\fP What information is required - \fIwhere\fP Where to put the information -.sp -The following information is available: -.sp - PCRE_INFO_BACKREFMAX Number of highest back reference - PCRE_INFO_CAPTURECOUNT Number of capturing subpatterns - PCRE_INFO_DEFAULT_TABLES Pointer to default tables - PCRE_INFO_FIRSTBYTE Fixed first byte for a match, or - -1 for start of string - or after newline, or - -2 otherwise - PCRE_INFO_FIRSTTABLE Table of first bytes - (after studying) - PCRE_INFO_LASTLITERAL Literal last byte required - PCRE_INFO_NAMECOUNT Number of named subpatterns - PCRE_INFO_NAMEENTRYSIZE Size of name table entry - PCRE_INFO_NAMETABLE Pointer to name table - PCRE_INFO_OPTIONS Options used for compilation - PCRE_INFO_SIZE Size of compiled pattern - PCRE_INFO_STUDYSIZE Size of study data -.sp -The yield of the function is zero on success or: -.sp - PCRE_ERROR_NULL the argument \fIcode\fP was NULL - the argument \fIwhere\fP was NULL - PCRE_ERROR_BADMAGIC the "magic number" was not found - PCRE_ERROR_BADOPTION the value of \fIwhat\fP was invalid -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_get_named_substring.3 b/srclib/pcre/doc/pcre_get_named_substring.3 deleted file mode 100644 index 9ce27ba39e..0000000000 --- a/srclib/pcre/doc/pcre_get_named_substring.3 +++ /dev/null @@ -1,45 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_get_named_substring(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, const char *\fIstringname\fP, -.ti +5n -.B const char **\fIstringptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for extracting a captured substring by name. The -arguments are: -.sp - \fIcode\fP Compiled pattern - \fIsubject\fP Subject that has been successfully matched - \fIovector\fP Offset vector that \fBpcre_exec()\fP used - \fIstringcount\fP Value returned by \fBpcre_exec()\fP - \fIstringname\fP Name of the required substring - \fIstringptr\fP Where to put the string pointer -.sp -The memory in which the substring is placed is obtained by calling -\fBpcre_malloc()\fP. The yield of the function is the length of the extracted -substring, PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or -PCRE_ERROR_NOSUBSTRING if the string name is invalid. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_get_stringnumber.3 b/srclib/pcre/doc/pcre_get_stringnumber.3 deleted file mode 100644 index 8c7289474d..0000000000 --- a/srclib/pcre/doc/pcre_get_stringnumber.3 +++ /dev/null @@ -1,35 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_get_stringnumber(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIname\fP); -. -.SH DESCRIPTION -.rs -.sp -This convenience function finds the number of a named substring capturing -parenthesis in a compiled pattern. Its arguments are: -.sp - \fIcode\fP Compiled regular expression - \fIname\fP Name whose number is required -.sp -The yield of the function is the number of the parenthesis if the name is -found, or PCRE_ERROR_NOSUBSTRING otherwise. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_get_substring.3 b/srclib/pcre/doc/pcre_get_substring.3 deleted file mode 100644 index 9bef5d3abd..0000000000 --- a/srclib/pcre/doc/pcre_get_substring.3 +++ /dev/null @@ -1,42 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, int \fIstringnumber\fP, -.ti +5n -.B const char **\fIstringptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for extracting a captured substring. The -arguments are: -.sp - \fIsubject\fP Subject that has been successfully matched - \fIovector\fP Offset vector that \fBpcre_exec()\fP used - \fIstringcount\fP Value returned by \fBpcre_exec()\fP - \fIstringnumber\fP Number of the required substring - \fIstringptr\fP Where to put the string pointer -.sp -The memory in which the substring is placed is obtained by calling -\fBpcre_malloc()\fP. The yield of the function is the length of the substring, -PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or -PCRE_ERROR_NOSUBSTRING if the string number is invalid. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_get_substring_list.3 b/srclib/pcre/doc/pcre_get_substring_list.3 deleted file mode 100644 index 29ae4420f3..0000000000 --- a/srclib/pcre/doc/pcre_get_substring_list.3 +++ /dev/null @@ -1,40 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_get_substring_list(const char *\fIsubject\fP, -.ti +5n -.B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);" -. -.SH DESCRIPTION -.rs -.sp -This is a convenience function for extracting a list of all the captured -substrings. The arguments are: -.sp - \fIsubject\fP Subject that has been successfully matched - \fIovector\fP Offset vector that \fBpcre_exec\fP used - \fIstringcount\fP Value returned by \fBpcre_exec\fP - \fIlistptr\fP Where to put a pointer to the list -.sp -The memory in which the substrings and the list are placed is obtained by -calling \fBpcre_malloc()\fP. A pointer to a list of pointers is put in -the variable whose address is in \fIlistptr\fP. The list is terminated by a -NULL pointer. The yield of the function is zero on success or -PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_info.3 b/srclib/pcre/doc/pcre_info.3 deleted file mode 100644 index 540c152822..0000000000 --- a/srclib/pcre/doc/pcre_info.3 +++ /dev/null @@ -1,27 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int -.B *\fIfirstcharptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This function is obsolete. You should be using \fBpcre_fullinfo()\fP instead. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_maketables.3 b/srclib/pcre/doc/pcre_maketables.3 deleted file mode 100644 index fdc5914e5c..0000000000 --- a/srclib/pcre/doc/pcre_maketables.3 +++ /dev/null @@ -1,30 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B const unsigned char *pcre_maketables(void); -. -.SH DESCRIPTION -.rs -.sp -This function builds a set of character tables for character values less than -256. These can be passed to \fBpcre_compile()\fP to override PCRE's internal, -built-in tables (which were made by \fBpcre_maketables()\fP when PCRE was -compiled). You might want to do this if you are using a non-standard locale. -The function yields a pointer to the tables. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_study.3 b/srclib/pcre/doc/pcre_study.3 deleted file mode 100644 index df428d0afc..0000000000 --- a/srclib/pcre/doc/pcre_study.3 +++ /dev/null @@ -1,43 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP, -.ti +5n -.B const char **\fIerrptr\fP); -. -.SH DESCRIPTION -.rs -.sp -This function studies a compiled pattern, to see if additional information can -be extracted that might speed up matching. Its arguments are: -.sp - \fIcode\fP A compiled regular expression - \fIoptions\fP Options for \fBpcre_study()\fP - \fIerrptr\fP Where to put an error message -.sp -If the function succeeds, it returns a value that can be passed to -\fBpcre_exec()\fP via its \fIextra\fP argument. -.P -If the function returns NULL, either it could not find any additional -information, or there was an error. You can tell the difference by looking at -the error value. It is NULL in first case. -.P -There are currently no options defined; the value of the second argument should -always be zero. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcre_version.3 b/srclib/pcre/doc/pcre_version.3 deleted file mode 100644 index 9b07407a42..0000000000 --- a/srclib/pcre/doc/pcre_version.3 +++ /dev/null @@ -1,27 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH SYNOPSIS -.rs -.sp -.B #include -.PP -.SM -.br -.B char *pcre_version(void); -. -.SH DESCRIPTION -.rs -.sp -This function returns a character string that gives the version number of the -PCRE library and the date of its release. -.P -There is a complete description of the PCRE native API in the -.\" HREF -\fBpcreapi\fP -.\" -page and a description of the POSIX API in the -.\" HREF -\fBpcreposix\fP -.\" -page. diff --git a/srclib/pcre/doc/pcreapi.3 b/srclib/pcre/doc/pcreapi.3 deleted file mode 100644 index 42a4e59c96..0000000000 --- a/srclib/pcre/doc/pcreapi.3 +++ /dev/null @@ -1,1288 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PCRE NATIVE API" -.rs -.sp -.B #include -.PP -.SM -.br -.B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP, -.ti +5n -.B const char **\fIerrptr\fP, int *\fIerroffset\fP, -.ti +5n -.B const unsigned char *\fItableptr\fP); -.PP -.br -.B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP, -.ti +5n -.B const char **\fIerrptr\fP); -.PP -.br -.B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP," -.ti +5n -.B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP, -.ti +5n -.B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP); -.PP -.br -.B int pcre_copy_named_substring(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, const char *\fIstringname\fP, -.ti +5n -.B char *\fIbuffer\fP, int \fIbuffersize\fP); -.PP -.br -.B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP, -.ti +5n -.B int \fIbuffersize\fP); -.PP -.br -.B int pcre_get_named_substring(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, const char *\fIstringname\fP, -.ti +5n -.B const char **\fIstringptr\fP); -.PP -.br -.B int pcre_get_stringnumber(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIname\fP); -.PP -.br -.B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, int \fIstringnumber\fP, -.ti +5n -.B const char **\fIstringptr\fP); -.PP -.br -.B int pcre_get_substring_list(const char *\fIsubject\fP, -.ti +5n -.B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);" -.PP -.br -.B void pcre_free_substring(const char *\fIstringptr\fP); -.PP -.br -.B void pcre_free_substring_list(const char **\fIstringptr\fP); -.PP -.br -.B const unsigned char *pcre_maketables(void); -.PP -.br -.B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP," -.ti +5n -.B int \fIwhat\fP, void *\fIwhere\fP); -.PP -.br -.B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int -.B *\fIfirstcharptr\fP); -.PP -.br -.B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP); -.PP -.br -.B char *pcre_version(void); -.PP -.br -.B void *(*pcre_malloc)(size_t); -.PP -.br -.B void (*pcre_free)(void *); -.PP -.br -.B void *(*pcre_stack_malloc)(size_t); -.PP -.br -.B void (*pcre_stack_free)(void *); -.PP -.br -.B int (*pcre_callout)(pcre_callout_block *); -. -. -.SH "PCRE API OVERVIEW" -.rs -.sp -PCRE has its own native API, which is described in this document. There is also -a set of wrapper functions that correspond to the POSIX regular expression API. -These are described in the -.\" HREF -\fBpcreposix\fP -.\" -documentation. -.P -The native API function prototypes are defined in the header file \fBpcre.h\fP, -and on Unix systems the library itself is called \fBlibpcre\fP. It can -normally be accessed by adding \fB-lpcre\fP to the command for linking an -application that uses PCRE. The header file defines the macros PCRE_MAJOR and -PCRE_MINOR to contain the major and minor release numbers for the library. -Applications can use these to include support for different releases of PCRE. -.P -The functions \fBpcre_compile()\fP, \fBpcre_study()\fP, and \fBpcre_exec()\fP -are used for compiling and matching regular expressions. A sample program that -demonstrates the simplest way of using them is provided in the file called -\fIpcredemo.c\fP in the source distribution. The -.\" HREF -\fBpcresample\fP -.\" -documentation describes how to run it. -.P -In addition to the main compiling and matching functions, there are convenience -functions for extracting captured substrings from a matched subject string. -They are: -.sp - \fBpcre_copy_substring()\fP - \fBpcre_copy_named_substring()\fP - \fBpcre_get_substring()\fP - \fBpcre_get_named_substring()\fP - \fBpcre_get_substring_list()\fP - \fBpcre_get_stringnumber()\fP -.sp -\fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also -provided, to free the memory used for extracted strings. -.P -The function \fBpcre_maketables()\fP is used to build a set of character tables -in the current locale for passing to \fBpcre_compile()\fP or \fBpcre_exec()\fP. -This is an optional facility that is provided for specialist use. Most -commonly, no special tables are passed, in which case internal tables that are -generated when PCRE is built are used. -.P -The function \fBpcre_fullinfo()\fP is used to find out information about a -compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only -some of the available information, but is retained for backwards compatibility. -The function \fBpcre_version()\fP returns a pointer to a string containing the -version of PCRE and its date of release. -.P -The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain -the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions, -respectively. PCRE calls the memory management functions via these variables, -so a calling program can replace them if it wishes to intercept the calls. This -should be done before calling any PCRE functions. -.P -The global variables \fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP are also -indirections to memory management functions. These special functions are used -only when PCRE is compiled to use the heap for remembering data, instead of -recursive function calls. This is a non-standard way of building PCRE, for use -in environments that have limited stacks. Because of the greater use of memory -management, it runs more slowly. Separate functions are provided so that -special-purpose external code can be used for this case. When used, these -functions are always called in a stack-like manner (last obtained, first -freed), and always for memory blocks of the same size. -.P -The global variable \fBpcre_callout\fP initially contains NULL. It can be set -by the caller to a "callout" function, which PCRE will then call at specified -points during a matching operation. Details are given in the -.\" HREF -\fBpcrecallout\fP -.\" -documentation. -. -. -.SH MULTITHREADING -.rs -.sp -The PCRE functions can be used in multi-threading applications, with the -proviso that the memory management functions pointed to by \fBpcre_malloc\fP, -\fBpcre_free\fP, \fBpcre_stack_malloc\fP, and \fBpcre_stack_free\fP, and the -callout function pointed to by \fBpcre_callout\fP, are shared by all threads. -.P -The compiled form of a regular expression is not altered during matching, so -the same compiled pattern can safely be used by several threads at once. -. -. -.SH "SAVING PRECOMPILED PATTERNS FOR LATER USE" -.rs -.sp -The compiled form of a regular expression can be saved and re-used at a later -time, possibly by a different program, and even on a host other than the one on -which it was compiled. Details are given in the -.\" HREF -\fBpcreprecompile\fP -.\" -documentation. -. -. -.SH "CHECKING BUILD-TIME OPTIONS" -.rs -.sp -.B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP); -.PP -The function \fBpcre_config()\fP makes it possible for a PCRE client to -discover which optional features have been compiled into the PCRE library. The -.\" HREF -\fBpcrebuild\fP -.\" -documentation has more details about these optional features. -.P -The first argument for \fBpcre_config()\fP is an integer, specifying which -information is required; the second argument is a pointer to a variable into -which the information is placed. The following information is available: -.sp - PCRE_CONFIG_UTF8 -.sp -The output is an integer that is set to one if UTF-8 support is available; -otherwise it is set to zero. -.sp - PCRE_CONFIG_UNICODE_PROPERTIES -.sp -The output is an integer that is set to one if support for Unicode character -properties is available; otherwise it is set to zero. -.sp - PCRE_CONFIG_NEWLINE -.sp -The output is an integer that is set to the value of the code that is used for -the newline character. It is either linefeed (10) or carriage return (13), and -should normally be the standard character for your operating system. -.sp - PCRE_CONFIG_LINK_SIZE -.sp -The output is an integer that contains the number of bytes used for internal -linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values -allow larger regular expressions to be compiled, at the expense of slower -matching. The default value of 2 is sufficient for all but the most massive -patterns, since it allows the compiled pattern to be up to 64K in size. -.sp - PCRE_CONFIG_POSIX_MALLOC_THRESHOLD -.sp -The output is an integer that contains the threshold above which the POSIX -interface uses \fBmalloc()\fP for output vectors. Further details are given in -the -.\" HREF -\fBpcreposix\fP -.\" -documentation. -.sp - PCRE_CONFIG_MATCH_LIMIT -.sp -The output is an integer that gives the default limit for the number of -internal matching function calls in a \fBpcre_exec()\fP execution. Further -details are given with \fBpcre_exec()\fP below. -.sp - PCRE_CONFIG_STACKRECURSE -.sp -The output is an integer that is set to one if internal recursion is -implemented by recursive function calls that use the stack to remember their -state. This is the usual way that PCRE is compiled. The output is zero if PCRE -was compiled to use blocks of data on the heap instead of recursive function -calls. In this case, \fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP are -called to manage memory blocks on the heap, thus avoiding the use of the stack. -. -. -.SH "COMPILING A PATTERN" -.rs -.sp -.B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP, -.ti +5n -.B const char **\fIerrptr\fP, int *\fIerroffset\fP, -.ti +5n -.B const unsigned char *\fItableptr\fP); -.P -The function \fBpcre_compile()\fP is called to compile a pattern into an -internal form. The pattern is a C string terminated by a binary zero, and -is passed in the \fIpattern\fP argument. A pointer to a single block of memory -that is obtained via \fBpcre_malloc\fP is returned. This contains the compiled -code and related data. The \fBpcre\fP type is defined for the returned block; -this is a typedef for a structure whose contents are not externally defined. It -is up to the caller to free the memory when it is no longer required. -.P -Although the compiled code of a PCRE regex is relocatable, that is, it does not -depend on memory location, the complete \fBpcre\fP data block is not -fully relocatable, because it may contain a copy of the \fItableptr\fP -argument, which is an address (see below). -.P -The \fIoptions\fP argument contains independent bits that affect the -compilation. It should be zero if no options are required. The available -options are described below. Some of them, in particular, those that are -compatible with Perl, can also be set and unset from within the pattern (see -the detailed description in the -.\" HREF -\fBpcrepattern\fP -.\" -documentation). For these options, the contents of the \fIoptions\fP argument -specifies their initial settings at the start of compilation and execution. The -PCRE_ANCHORED option can be set at the time of matching as well as at compile -time. -.P -If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately. -Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns -NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual -error message. The offset from the start of the pattern to the character where -the error was discovered is placed in the variable pointed to by -\fIerroffset\fP, which must not be NULL. If it is, an immediate error is given. -.P -If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of -character tables that are built when PCRE is compiled, using the default C -locale. Otherwise, \fItableptr\fP must be an address that is the result of a -call to \fBpcre_maketables()\fP. This value is stored with the compiled -pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is -passed to it. For more discussion, see the section on locale support below. -.P -This code fragment shows a typical straightforward call to \fBpcre_compile()\fP: -.sp - pcre *re; - const char *error; - int erroffset; - re = pcre_compile( - "^A.*Z", /* the pattern */ - 0, /* default options */ - &error, /* for error message */ - &erroffset, /* for error offset */ - NULL); /* use default character tables */ -.sp -The following names for option bits are defined in the \fBpcre.h\fP header -file: -.sp - PCRE_ANCHORED -.sp -If this bit is set, the pattern is forced to be "anchored", that is, it is -constrained to match only at the first matching point in the string that is -being searched (the "subject string"). This effect can also be achieved by -appropriate constructs in the pattern itself, which is the only way to do it in -Perl. -.sp - PCRE_AUTO_CALLOUT -.sp -If this bit is set, \fBpcre_compile()\fP automatically inserts callout items, -all with number 255, before each pattern item. For discussion of the callout -facility, see the -.\" HREF -\fBpcrecallout\fP -.\" -documentation. -.sp - PCRE_CASELESS -.sp -If this bit is set, letters in the pattern match both upper and lower case -letters. It is equivalent to Perl's /i option, and it can be changed within a -pattern by a (?i) option setting. When running in UTF-8 mode, case support for -high-valued characters is available only when PCRE is built with Unicode -character property support. -.sp - PCRE_DOLLAR_ENDONLY -.sp -If this bit is set, a dollar metacharacter in the pattern matches only at the -end of the subject string. Without this option, a dollar also matches -immediately before the final character if it is a newline (but not before any -other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is -set. There is no equivalent to this option in Perl, and no way to set it within -a pattern. -.sp - PCRE_DOTALL -.sp -If this bit is set, a dot metacharater in the pattern matches all characters, -including newlines. Without it, newlines are excluded. This option is -equivalent to Perl's /s option, and it can be changed within a pattern by a -(?s) option setting. A negative class such as [^a] always matches a newline -character, independent of the setting of this option. -.sp - PCRE_EXTENDED -.sp -If this bit is set, whitespace data characters in the pattern are totally -ignored except when escaped or inside a character class. Whitespace does not -include the VT character (code 11). In addition, characters between an -unescaped # outside a character class and the next newline character, -inclusive, are also ignored. This is equivalent to Perl's /x option, and it can -be changed within a pattern by a (?x) option setting. -.P -This option makes it possible to include comments inside complicated patterns. -Note, however, that this applies only to data characters. Whitespace characters -may never appear within special character sequences in a pattern, for example -within the sequence (?( which introduces a conditional subpattern. -.sp - PCRE_EXTRA -.sp -This option was invented in order to turn on additional functionality of PCRE -that is incompatible with Perl, but it is currently of very little use. When -set, any backslash in a pattern that is followed by a letter that has no -special meaning causes an error, thus reserving these combinations for future -expansion. By default, as in Perl, a backslash followed by a letter with no -special meaning is treated as a literal. There are at present no other features -controlled by this option. It can also be set by a (?X) option setting within a -pattern. -.sp - PCRE_MULTILINE -.sp -By default, PCRE treats the subject string as consisting of a single line of -characters (even if it actually contains newlines). The "start of line" -metacharacter (^) matches only at the start of the string, while the "end of -line" metacharacter ($) matches only at the end of the string, or before a -terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as -Perl. -.P -When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs -match immediately following or immediately before any newline in the subject -string, respectively, as well as at the very start and end. This is equivalent -to Perl's /m option, and it can be changed within a pattern by a (?m) option -setting. If there are no "\en" characters in a subject string, or no -occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect. -.sp - PCRE_NO_AUTO_CAPTURE -.sp -If this option is set, it disables the use of numbered capturing parentheses in -the pattern. Any opening parenthesis that is not followed by ? behaves as if it -were followed by ?: but named parentheses can still be used for capturing (and -they acquire numbers in the usual way). There is no equivalent of this option -in Perl. -.sp - PCRE_UNGREEDY -.sp -This option inverts the "greediness" of the quantifiers so that they are not -greedy by default, but become greedy if followed by "?". It is not compatible -with Perl. It can also be set by a (?U) option setting within the pattern. -.sp - PCRE_UTF8 -.sp -This option causes PCRE to regard both the pattern and the subject as strings -of UTF-8 characters instead of single-byte character strings. However, it is -available only when PCRE is built to include UTF-8 support. If not, the use -of this option provokes an error. Details of how this option changes the -behaviour of PCRE are given in the -.\" HTML -.\" -section on UTF-8 support -.\" -in the main -.\" HREF -\fBpcre\fP -.\" -page. -.sp - PCRE_NO_UTF8_CHECK -.sp -When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is -automatically checked. If an invalid UTF-8 sequence of bytes is found, -\fBpcre_compile()\fP returns an error. If you already know that your pattern is -valid, and you want to skip this check for performance reasons, you can set the -PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid -UTF-8 string as a pattern is undefined. It may cause your program to crash. -Note that this option can also be passed to \fBpcre_exec()\fP, to suppress the -UTF-8 validity checking of subject strings. -. -. -.SH "STUDYING A PATTERN" -.rs -.sp -.B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP, -.ti +5n -.B const char **\fIerrptr\fP); -.PP -If a compiled pattern is going to be used several times, it is worth spending -more time analyzing it in order to speed up the time taken for matching. The -function \fBpcre_study()\fP takes a pointer to a compiled pattern as its first -argument. If studying the pattern produces additional information that will -help speed up matching, \fBpcre_study()\fP returns a pointer to a -\fBpcre_extra\fP block, in which the \fIstudy_data\fP field points to the -results of the study. -.P -The returned value from \fBpcre_study()\fP can be passed directly to -\fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other -fields that can be set by the caller before the block is passed; these are -described -.\" HTML -.\" -below -.\" -in the section on matching a pattern. -.P -If studying the pattern does not produce any additional information, -\fBpcre_study()\fP returns NULL. In that circumstance, if the calling program -wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its -own \fBpcre_extra\fP block. -.P -The second argument of \fBpcre_study()\fP contains option bits. At present, no -options are defined, and this argument should always be zero. -.P -The third argument for \fBpcre_study()\fP is a pointer for an error message. If -studying succeeds (even if no data is returned), the variable it points to is -set to NULL. Otherwise it points to a textual error message. You should -therefore test the error pointer for NULL after calling \fBpcre_study()\fP, to -be sure that it has run successfully. -.P -This is a typical call to \fBpcre_study\fP(): -.sp - pcre_extra *pe; - pe = pcre_study( - re, /* result of pcre_compile() */ - 0, /* no options exist */ - &error); /* set to NULL or points to a message */ -.sp -At present, studying a pattern is useful only for non-anchored patterns that do -not have a single fixed starting character. A bitmap of possible starting -bytes is created. -. -. -.\" HTML -.SH "LOCALE SUPPORT" -.rs -.sp -PCRE handles caseless matching, and determines whether characters are letters, -digits, or whatever, by reference to a set of tables, indexed by character -value. (When running in UTF-8 mode, this applies only to characters with codes -less than 128. Higher-valued codes never match escapes such as \ew or \ed, but -can be tested with \ep if PCRE is built with Unicode character property -support.) -.P -An internal set of tables is created in the default C locale when PCRE is -built. This is used when the final argument of \fBpcre_compile()\fP is NULL, -and is sufficient for many applications. An alternative set of tables can, -however, be supplied. These may be created in a different locale from the -default. As more and more applications change to using Unicode, the need for -this locale support is expected to die away. -.P -External tables are built by calling the \fBpcre_maketables()\fP function, -which has no arguments, in the relevant locale. The result can then be passed -to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For -example, to build and use tables that are appropriate for the French locale -(where accented characters with values greater than 128 are treated as letters), -the following code could be used: -.sp - setlocale(LC_CTYPE, "fr_FR"); - tables = pcre_maketables(); - re = pcre_compile(..., tables); -.sp -When \fBpcre_maketables()\fP runs, the tables are built in memory that is -obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure -that the memory containing the tables remains available for as long as it is -needed. -.P -The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled -pattern, and the same tables are used via this pointer by \fBpcre_study()\fP -and normally also by \fBpcre_exec()\fP. Thus, by default, for any single -pattern, compilation, studying and matching all happen in the same locale, but -different patterns can be compiled in different locales. -.P -It is possible to pass a table pointer or NULL (indicating the use of the -internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose, -this facility could be used to match a pattern in a different locale from the -one in which it was compiled. Passing table pointers at run time is discussed -below in the section on matching a pattern. -. -. -.SH "INFORMATION ABOUT A PATTERN" -.rs -.sp -.B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP," -.ti +5n -.B int \fIwhat\fP, void *\fIwhere\fP); -.PP -The \fBpcre_fullinfo()\fP function returns information about a compiled -pattern. It replaces the obsolete \fBpcre_info()\fP function, which is -nevertheless retained for backwards compability (and is documented below). -.P -The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled -pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if -the pattern was not studied. The third argument specifies which piece of -information is required, and the fourth argument is a pointer to a variable -to receive the data. The yield of the function is zero for success, or one of -the following negative numbers: -.sp - PCRE_ERROR_NULL the argument \fIcode\fP was NULL - the argument \fIwhere\fP was NULL - PCRE_ERROR_BADMAGIC the "magic number" was not found - PCRE_ERROR_BADOPTION the value of \fIwhat\fP was invalid -.sp -The "magic number" is placed at the start of each compiled pattern as an simple -check against passing an arbitrary memory pointer. Here is a typical call of -\fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern: -.sp - int rc; - unsigned long int length; - rc = pcre_fullinfo( - re, /* result of pcre_compile() */ - pe, /* result of pcre_study(), or NULL */ - PCRE_INFO_SIZE, /* what is required */ - &length); /* where to put the data */ -.sp -The possible values for the third argument are defined in \fBpcre.h\fP, and are -as follows: -.sp - PCRE_INFO_BACKREFMAX -.sp -Return the number of the highest back reference in the pattern. The fourth -argument should point to an \fBint\fP variable. Zero is returned if there are -no back references. -.sp - PCRE_INFO_CAPTURECOUNT -.sp -Return the number of capturing subpatterns in the pattern. The fourth argument -should point to an \fBint\fP variable. -.sp - PCRE_INFO_DEFAULTTABLES -.sp -Return a pointer to the internal default character tables within PCRE. The -fourth argument should point to an \fBunsigned char *\fP variable. This -information call is provided for internal use by the \fBpcre_study()\fP -function. External callers can cause PCRE to use its internal tables by passing -a NULL table pointer. -.sp - PCRE_INFO_FIRSTBYTE -.sp -Return information about the first byte of any matched string, for a -non-anchored pattern. (This option used to be called PCRE_INFO_FIRSTCHAR; the -old name is still recognized for backwards compatibility.) -.P -If there is a fixed first byte, for example, from a pattern such as -(cat|cow|coyote), it is returned in the integer pointed to by \fIwhere\fP. -Otherwise, if either -.sp -(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch -starts with "^", or -.sp -(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set -(if it were set, the pattern would be anchored), -.sp --1 is returned, indicating that the pattern matches only at the start of a -subject string or after any newline within the string. Otherwise -2 is -returned. For anchored patterns, -2 is returned. -.sp - PCRE_INFO_FIRSTTABLE -.sp -If the pattern was studied, and this resulted in the construction of a 256-bit -table indicating a fixed set of bytes for the first byte in any matching -string, a pointer to the table is returned. Otherwise NULL is returned. The -fourth argument should point to an \fBunsigned char *\fP variable. -.sp - PCRE_INFO_LASTLITERAL -.sp -Return the value of the rightmost literal byte that must exist in any matched -string, other than at its start, if such a byte has been recorded. The fourth -argument should point to an \fBint\fP variable. If there is no such byte, -1 is -returned. For anchored patterns, a last literal byte is recorded only if it -follows something of variable length. For example, for the pattern -/^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value -is -1. -.sp - PCRE_INFO_NAMECOUNT - PCRE_INFO_NAMEENTRYSIZE - PCRE_INFO_NAMETABLE -.sp -PCRE supports the use of named as well as numbered capturing parentheses. The -names are just an additional way of identifying the parentheses, which still -acquire numbers. A convenience function called \fBpcre_get_named_substring()\fP -is provided for extracting an individual captured substring by name. It is also -possible to extract the data directly, by first converting the name to a number -in order to access the correct pointers in the output vector (described with -\fBpcre_exec()\fP below). To do the conversion, you need to use the -name-to-number map, which is described by these three values. -.P -The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives -the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each -entry; both of these return an \fBint\fP value. The entry size depends on the -length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first -entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry -are the number of the capturing parenthesis, most significant byte first. The -rest of the entry is the corresponding name, zero terminated. The names are in -alphabetical order. For example, consider the following pattern (assume -PCRE_EXTENDED is set, so white space - including newlines - is ignored): -.sp -.\" JOIN - (?P (?P(\ed\ed)?\ed\ed) - - (?P\ed\ed) - (?P\ed\ed) ) -.sp -There are four named subpatterns, so the table has four entries, and each entry -in the table is eight bytes long. The table is as follows, with non-printing -bytes shows in hexadecimal, and undefined bytes shown as ??: -.sp - 00 01 d a t e 00 ?? - 00 05 d a y 00 ?? ?? - 00 04 m o n t h 00 - 00 02 y e a r 00 ?? -.sp -When writing code to extract data from named subpatterns using the -name-to-number map, remember that the length of each entry is likely to be -different for each compiled pattern. -.sp - PCRE_INFO_OPTIONS -.sp -Return a copy of the options with which the pattern was compiled. The fourth -argument should point to an \fBunsigned long int\fP variable. These option bits -are those specified in the call to \fBpcre_compile()\fP, modified by any -top-level option settings within the pattern itself. -.P -A pattern is automatically anchored by PCRE if all of its top-level -alternatives begin with one of the following: -.sp - ^ unless PCRE_MULTILINE is set - \eA always - \eG always -.\" JOIN - .* if PCRE_DOTALL is set and there are no back - references to the subpattern in which .* appears -.sp -For such patterns, the PCRE_ANCHORED bit is set in the options returned by -\fBpcre_fullinfo()\fP. -.sp - PCRE_INFO_SIZE -.sp -Return the size of the compiled pattern, that is, the value that was passed as -the argument to \fBpcre_malloc()\fP when PCRE was getting memory in which to -place the compiled data. The fourth argument should point to a \fBsize_t\fP -variable. -.sp - PCRE_INFO_STUDYSIZE -.sp -Return the size of the data block pointed to by the \fIstudy_data\fP field in -a \fBpcre_extra\fP block. That is, it is the value that was passed to -\fBpcre_malloc()\fP when PCRE was getting memory into which to place the data -created by \fBpcre_study()\fP. The fourth argument should point to a -\fBsize_t\fP variable. -. -. -.SH "OBSOLETE INFO FUNCTION" -.rs -.sp -.B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int -.B *\fIfirstcharptr\fP); -.PP -The \fBpcre_info()\fP function is now obsolete because its interface is too -restrictive to return all the available data about a compiled pattern. New -programs should use \fBpcre_fullinfo()\fP instead. The yield of -\fBpcre_info()\fP is the number of capturing subpatterns, or one of the -following negative numbers: -.sp - PCRE_ERROR_NULL the argument \fIcode\fP was NULL - PCRE_ERROR_BADMAGIC the "magic number" was not found -.sp -If the \fIoptptr\fP argument is not NULL, a copy of the options with which the -pattern was compiled is placed in the integer it points to (see -PCRE_INFO_OPTIONS above). -.P -If the pattern is not anchored and the \fIfirstcharptr\fP argument is not NULL, -it is used to pass back information about the first character of any matched -string (see PCRE_INFO_FIRSTBYTE above). -. -. -.SH "MATCHING A PATTERN" -.rs -.sp -.B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP," -.ti +5n -.B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP, -.ti +5n -.B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP); -.P -The function \fBpcre_exec()\fP is called to match a subject string against a -compiled pattern, which is passed in the \fIcode\fP argument. If the -pattern has been studied, the result of the study should be passed in the -\fIextra\fP argument. -.P -In most applications, the pattern will have been compiled (and optionally -studied) in the same process that calls \fBpcre_exec()\fP. However, it is -possible to save compiled patterns and study data, and then use them later -in different processes, possibly even on different hosts. For a discussion -about this, see the -.\" HREF -\fBpcreprecompile\fP -.\" -documentation. -.P -Here is an example of a simple call to \fBpcre_exec()\fP: -.sp - int rc; - int ovector[30]; - rc = pcre_exec( - re, /* result of pcre_compile() */ - NULL, /* we didn't study the pattern */ - "some string", /* the subject string */ - 11, /* the length of the subject string */ - 0, /* start at offset 0 in the subject */ - 0, /* default options */ - ovector, /* vector of integers for substring information */ - 30); /* number of elements in the vector (NOT size in bytes) */ -. -.\" HTML -.SS "Extra data for \fBpcre_exec()\fR" -.rs -.sp -If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP -data block. The \fBpcre_study()\fP function returns such a block (when it -doesn't return NULL), but you can also create one for yourself, and pass -additional information in it. The fields in a \fBpcre_extra\fP block are as -follows: -.sp - unsigned long int \fIflags\fP; - void *\fIstudy_data\fP; - unsigned long int \fImatch_limit\fP; - void *\fIcallout_data\fP; - const unsigned char *\fItables\fP; -.sp -The \fIflags\fP field is a bitmap that specifies which of the other fields -are set. The flag bits are: -.sp - PCRE_EXTRA_STUDY_DATA - PCRE_EXTRA_MATCH_LIMIT - PCRE_EXTRA_CALLOUT_DATA - PCRE_EXTRA_TABLES -.sp -Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the -\fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with -the appropriate flag bit. You should not set this yourself, but you may add to -the block by setting the other fields and their corresponding flag bits. -.P -The \fImatch_limit\fP field provides a means of preventing PCRE from using up a -vast amount of resources when running patterns that are not going to match, -but which have a very large number of possibilities in their search trees. The -classic example is the use of nested unlimited repeats. -.P -Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly -(sometimes recursively). The limit is imposed on the number of times this -function is called during a match, which has the effect of limiting the amount -of recursion and backtracking that can take place. For patterns that are not -anchored, the count starts from zero for each position in the subject string. -.P -The default limit for the library can be set when PCRE is built; the default -default is 10 million, which handles all but the most extreme cases. You can -reduce the default by suppling \fBpcre_exec()\fP with a \fBpcre_extra\fP block -in which \fImatch_limit\fP is set to a smaller value, and -PCRE_EXTRA_MATCH_LIMIT is set in the \fIflags\fP field. If the limit is -exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_MATCHLIMIT. -.P -The \fIpcre_callout\fP field is used in conjunction with the "callout" feature, -which is described in the -.\" HREF -\fBpcrecallout\fP -.\" -documentation. -.P -The \fItables\fP field is used to pass a character tables pointer to -\fBpcre_exec()\fP; this overrides the value that is stored with the compiled -pattern. A non-NULL value is stored with the compiled pattern only if custom -tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument. -If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's -internal tables to be used. This facility is helpful when re-using patterns -that have been saved after compiling with an external set of tables, because -the external tables might be at a different address when \fBpcre_exec()\fP is -called. See the -.\" HREF -\fBpcreprecompile\fP -.\" -documentation for a discussion of saving compiled patterns for later use. -. -.SS "Option bits for \fBpcre_exec()\fP" -.rs -.sp -The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be -zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NOTBOL, -PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL. -.sp - PCRE_ANCHORED -.sp -The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first -matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out -to be anchored by virtue of its contents, it cannot be made unachored at -matching time. -.sp - PCRE_NOTBOL -.sp -This option specifies that first character of the subject string is not the -beginning of a line, so the circumflex metacharacter should not match before -it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex -never to match. This option affects only the behaviour of the circumflex -metacharacter. It does not affect \eA. -.sp - PCRE_NOTEOL -.sp -This option specifies that the end of the subject string is not the end of a -line, so the dollar metacharacter should not match it nor (except in multiline -mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at -compile time) causes dollar never to match. This option affects only the -behaviour of the dollar metacharacter. It does not affect \eZ or \ez. -.sp - PCRE_NOTEMPTY -.sp -An empty string is not considered to be a valid match if this option is set. If -there are alternatives in the pattern, they are tried. If all the alternatives -match the empty string, the entire match fails. For example, if the pattern -.sp - a?b? -.sp -is applied to a string not beginning with "a" or "b", it matches the empty -string at the start of the subject. With PCRE_NOTEMPTY set, this match is not -valid, so PCRE searches further into the string for occurrences of "a" or "b". -.P -Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case -of a pattern match of the empty string within its \fBsplit()\fP function, and -when using the /g modifier. It is possible to emulate Perl's behaviour after -matching a null string by first trying the match again at the same offset with -PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the -starting offset (see below) and trying an ordinary match again. There is some -code that demonstrates how to do this in the \fIpcredemo.c\fP sample program. -.sp - PCRE_NO_UTF8_CHECK -.sp -When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8 -string is automatically checked when \fBpcre_exec()\fP is subsequently called. -The value of \fIstartoffset\fP is also checked to ensure that it points to the -start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found, -\fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP -contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned. -.P -If you already know that your subject is valid, and you want to skip these -checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when -calling \fBpcre_exec()\fP. You might want to do this for the second and -subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find -all the matches in a single subject string. However, you should be sure that -the value of \fIstartoffset\fP points to the start of a UTF-8 character. When -PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a -subject, or a value of \fIstartoffset\fP that does not point to the start of a -UTF-8 character, is undefined. Your program may crash. -.sp - PCRE_PARTIAL -.sp -This option turns on the partial matching feature. If the subject string fails -to match the pattern, but at some point during the matching process the end of -the subject was reached (that is, the subject partially matches the pattern and -the failure to match occurred only because there were not enough subject -characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of -PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what -may appear in the pattern. These are discussed in the -.\" HREF -\fBpcrepartial\fP -.\" -documentation. -. -.SS "The string to be matched by \fBpcre_exec()\fP" -.rs -.sp -The subject string is passed to \fBpcre_exec()\fP as a pointer in -\fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in -\fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a -UTF-8 character. Unlike the pattern string, the subject may contain binary zero -bytes. When the starting offset is zero, the search for a match starts at the -beginning of the subject, and this is by far the most common case. -.P -A non-zero starting offset is useful when searching for another match in the -same subject by calling \fBpcre_exec()\fP again after a previous success. -Setting \fIstartoffset\fP differs from just passing over a shortened string and -setting PCRE_NOTBOL in the case of a pattern that begins with any kind of -lookbehind. For example, consider the pattern -.sp - \eBiss\eB -.sp -which finds occurrences of "iss" in the middle of words. (\eB matches only if -the current position in the subject is not a word boundary.) When applied to -the string "Mississipi" the first call to \fBpcre_exec()\fP finds the first -occurrence. If \fBpcre_exec()\fP is called again with just the remainder of the -subject, namely "issipi", it does not match, because \eB is always false at the -start of the subject, which is deemed to be a word boundary. However, if -\fBpcre_exec()\fP is passed the entire string again, but with \fIstartoffset\fP -set to 4, it finds the second occurrence of "iss" because it is able to look -behind the starting point to discover that it is preceded by a letter. -.P -If a non-zero starting offset is passed when the pattern is anchored, one -attempt to match at the given offset is made. This can only succeed if the -pattern does not require the match to be at the start of the subject. -. -.SS "How \fBpcre_exec()\fP returns captured substrings" -.rs -.sp -In general, a pattern matches a certain portion of the subject, and in -addition, further substrings from the subject may be picked out by parts of the -pattern. Following the usage in Jeffrey Friedl's book, this is called -"capturing" in what follows, and the phrase "capturing subpattern" is used for -a fragment of a pattern that picks out a substring. PCRE supports several other -kinds of parenthesized subpattern that do not cause substrings to be captured. -.P -Captured substrings are returned to the caller via a vector of integer offsets -whose address is passed in \fIovector\fP. The number of elements in the vector -is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: -this argument is NOT the size of \fIovector\fP in bytes. -.P -The first two-thirds of the vector is used to pass back captured substrings, -each substring using a pair of integers. The remaining third of the vector is -used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns, -and is not available for passing back information. The length passed in -\fIovecsize\fP should always be a multiple of three. If it is not, it is -rounded down. -.P -When a match is successful, information about captured substrings is returned -in pairs of integers, starting at the beginning of \fIovector\fP, and -continuing up to two-thirds of its length at the most. The first element of a -pair is set to the offset of the first character in a substring, and the second -is set to the offset of the first character after the end of a substring. The -first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the -subject string matched by the entire pattern. The next pair is used for the -first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP -is the number of pairs that have been set. If there are no capturing -subpatterns, the return value from a successful match is 1, indicating that -just the first pair of offsets has been set. -.P -Some convenience functions are provided for extracting the captured substrings -as separate strings. These are described in the following section. -.P -It is possible for an capturing subpattern number \fIn+1\fP to match some -part of the subject when subpattern \fIn\fP has not been used at all. For -example, if the string "abc" is matched against the pattern (a|(z))(bc) -subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset -values corresponding to the unused subpattern are set to -1. -.P -If a capturing subpattern is matched repeatedly, it is the last portion of the -string that it matched that is returned. -.P -If the vector is too small to hold all the captured substring offsets, it is -used as far as possible (up to two-thirds of its length), and the function -returns a value of zero. In particular, if the substring offsets are not of -interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and -\fIovecsize\fP as zero. However, if the pattern contains back references and -the \fIovector\fP is not big enough to remember the related substrings, PCRE -has to get additional memory for use during matching. Thus it is usually -advisable to supply an \fIovector\fP. -.P -Note that \fBpcre_info()\fP can be used to find out how many capturing -subpatterns there are in a compiled pattern. The smallest size for -\fIovector\fP that will allow for \fIn\fP captured substrings, in addition to -the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3. -. -.SS "Return values from \fBpcre_exec()\fP" -.rs -.sp -If \fBpcre_exec()\fP fails, it returns a negative number. The following are -defined in the header file: -.sp - PCRE_ERROR_NOMATCH (-1) -.sp -The subject string did not match the pattern. -.sp - PCRE_ERROR_NULL (-2) -.sp -Either \fIcode\fP or \fIsubject\fP was passed as NULL, or \fIovector\fP was -NULL and \fIovecsize\fP was not zero. -.sp - PCRE_ERROR_BADOPTION (-3) -.sp -An unrecognized bit was set in the \fIoptions\fP argument. -.sp - PCRE_ERROR_BADMAGIC (-4) -.sp -PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch -the case when it is passed a junk pointer and to detect when a pattern that was -compiled in an environment of one endianness is run in an environment with the -other endianness. This is the error that PCRE gives when the magic number is -not present. -.sp - PCRE_ERROR_UNKNOWN_NODE (-5) -.sp -While running the pattern match, an unknown item was encountered in the -compiled pattern. This error could be caused by a bug in PCRE or by overwriting -of the compiled pattern. -.sp - PCRE_ERROR_NOMEMORY (-6) -.sp -If a pattern contains back references, but the \fIovector\fP that is passed to -\fBpcre_exec()\fP is not big enough to remember the referenced substrings, PCRE -gets a block of memory at the start of matching to use for this purpose. If the -call via \fBpcre_malloc()\fP fails, this error is given. The memory is -automatically freed at the end of matching. -.sp - PCRE_ERROR_NOSUBSTRING (-7) -.sp -This error is used by the \fBpcre_copy_substring()\fP, -\fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see -below). It is never returned by \fBpcre_exec()\fP. -.sp - PCRE_ERROR_MATCHLIMIT (-8) -.sp -The recursion and backtracking limit, as specified by the \fImatch_limit\fP -field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the -description above. -.sp - PCRE_ERROR_CALLOUT (-9) -.sp -This error is never generated by \fBpcre_exec()\fP itself. It is provided for -use by callout functions that want to yield a distinctive error code. See the -.\" HREF -\fBpcrecallout\fP -.\" -documentation for details. -.sp - PCRE_ERROR_BADUTF8 (-10) -.sp -A string that contains an invalid UTF-8 byte sequence was passed as a subject. -.sp - PCRE_ERROR_BADUTF8_OFFSET (-11) -.sp -The UTF-8 byte sequence that was passed as a subject was valid, but the value -of \fIstartoffset\fP did not point to the beginning of a UTF-8 character. -.sp - PCRE_ERROR_PARTIAL (-12) -.sp -The subject string did not match, but it did match partially. See the -.\" HREF -\fBpcrepartial\fP -.\" -documentation for details of partial matching. -.sp - PCRE_ERROR_BAD_PARTIAL (-13) -.sp -The PCRE_PARTIAL option was used with a compiled pattern containing items that -are not supported for partial matching. See the -.\" HREF -\fBpcrepartial\fP -.\" -documentation for details of partial matching. -.sp - PCRE_ERROR_INTERNAL (-14) -.sp -An unexpected internal error has occurred. This error could be caused by a bug -in PCRE or by overwriting of the compiled pattern. -.sp - PCRE_ERROR_BADCOUNT (-15) -.sp -This error is given if the value of the \fIovecsize\fP argument is negative. -. -. -.SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER" -.rs -.sp -.B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP, -.ti +5n -.B int \fIbuffersize\fP); -.PP -.br -.B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, int \fIstringnumber\fP, -.ti +5n -.B const char **\fIstringptr\fP); -.PP -.br -.B int pcre_get_substring_list(const char *\fIsubject\fP, -.ti +5n -.B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);" -.PP -Captured substrings can be accessed directly by using the offsets returned by -\fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions -\fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and -\fBpcre_get_substring_list()\fP are provided for extracting captured substrings -as new, separate, zero-terminated strings. These functions identify substrings -by number. The next section describes functions for extracting named -substrings. A substring that contains a binary zero is correctly extracted and -has a further zero added on the end, but the result is not, of course, -a C string. -.P -The first three arguments are the same for all three of these functions: -\fIsubject\fP is the subject string that has just been successfully matched, -\fIovector\fP is a pointer to the vector of integer offsets that was passed to -\fBpcre_exec()\fP, and \fIstringcount\fP is the number of substrings that were -captured by the match, including the substring that matched the entire regular -expression. This is the value returned by \fBpcre_exec()\fP if it is greater -than zero. If \fBpcre_exec()\fP returned zero, indicating that it ran out of -space in \fIovector\fP, the value passed as \fIstringcount\fP should be the -number of elements in the vector divided by three. -.P -The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP -extract a single substring, whose number is given as \fIstringnumber\fP. A -value of zero extracts the substring that matched the entire pattern, whereas -higher values extract the captured substrings. For \fBpcre_copy_substring()\fP, -the string is placed in \fIbuffer\fP, whose length is given by -\fIbuffersize\fP, while for \fBpcre_get_substring()\fP a new block of memory is -obtained via \fBpcre_malloc\fP, and its address is returned via -\fIstringptr\fP. The yield of the function is the length of the string, not -including the terminating zero, or one of -.sp - PCRE_ERROR_NOMEMORY (-6) -.sp -The buffer was too small for \fBpcre_copy_substring()\fP, or the attempt to get -memory failed for \fBpcre_get_substring()\fP. -.sp - PCRE_ERROR_NOSUBSTRING (-7) -.sp -There is no substring whose number is \fIstringnumber\fP. -.P -The \fBpcre_get_substring_list()\fP function extracts all available substrings -and builds a list of pointers to them. All this is done in a single block of -memory that is obtained via \fBpcre_malloc\fP. The address of the memory block -is returned via \fIlistptr\fP, which is also the start of the list of string -pointers. The end of the list is marked by a NULL pointer. The yield of the -function is zero if all went well, or -.sp - PCRE_ERROR_NOMEMORY (-6) -.sp -if the attempt to get the memory block failed. -.P -When any of these functions encounter a substring that is unset, which can -happen when capturing subpattern number \fIn+1\fP matches some part of the -subject, but subpattern \fIn\fP has not been used at all, they return an empty -string. This can be distinguished from a genuine zero-length substring by -inspecting the appropriate offset in \fIovector\fP, which is negative for unset -substrings. -.P -The two convenience functions \fBpcre_free_substring()\fP and -\fBpcre_free_substring_list()\fP can be used to free the memory returned by -a previous call of \fBpcre_get_substring()\fP or -\fBpcre_get_substring_list()\fP, respectively. They do nothing more than call -the function pointed to by \fBpcre_free\fP, which of course could be called -directly from a C program. However, PCRE is used in some situations where it is -linked via a special interface to another programming language which cannot use -\fBpcre_free\fP directly; it is for these cases that the functions are -provided. -. -. -.SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME" -.rs -.sp -.B int pcre_get_stringnumber(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIname\fP); -.PP -.br -.B int pcre_copy_named_substring(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, const char *\fIstringname\fP, -.ti +5n -.B char *\fIbuffer\fP, int \fIbuffersize\fP); -.PP -.br -.B int pcre_get_named_substring(const pcre *\fIcode\fP, -.ti +5n -.B const char *\fIsubject\fP, int *\fIovector\fP, -.ti +5n -.B int \fIstringcount\fP, const char *\fIstringname\fP, -.ti +5n -.B const char **\fIstringptr\fP); -.PP -To extract a substring by name, you first have to find associated number. -For example, for this pattern -.sp - (a+)b(?\ed+)... -.sp -the number of the subpattern called "xxx" is 2. You can find the number from -the name by calling \fBpcre_get_stringnumber()\fP. The first argument is the -compiled pattern, and the second is the name. The yield of the function is the -subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of -that name. -.P -Given the number, you can extract the substring directly, or use one of the -functions described in the previous section. For convenience, there are also -two functions that do the whole job. -.P -Most of the arguments of \fIpcre_copy_named_substring()\fP and -\fIpcre_get_named_substring()\fP are the same as those for the similarly named -functions that extract by number. As these are described in the previous -section, they are not re-described here. There are just two differences: -.P -First, instead of a substring number, a substring name is given. Second, there -is an extra argument, given at the start, which is a pointer to the compiled -pattern. This is needed in order to gain access to the name-to-number -translation table. -.P -These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they -then call \fIpcre_copy_substring()\fP or \fIpcre_get_substring()\fP, as -appropriate. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcrebuild.3 b/srclib/pcre/doc/pcrebuild.3 deleted file mode 100644 index 8ac588281d..0000000000 --- a/srclib/pcre/doc/pcrebuild.3 +++ /dev/null @@ -1,174 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PCRE BUILD-TIME OPTIONS" -.rs -.sp -This document describes the optional features of PCRE that can be selected when -the library is compiled. They are all selected, or deselected, by providing -options to the \fBconfigure\fP script that is run before the \fBmake\fP -command. The complete list of options for \fBconfigure\fP (which includes the -standard ones such as the selection of the installation directory) can be -obtained by running -.sp - ./configure --help -.sp -The following sections describe certain options whose names begin with --enable -or --disable. These settings specify changes to the defaults for the -\fBconfigure\fP command. Because of the way that \fBconfigure\fP works, ---enable and --disable always come in pairs, so the complementary option always -exists as well, but as it specifies the default, it is not described. -. -.SH "UTF-8 SUPPORT" -.rs -.sp -To build PCRE with support for UTF-8 character strings, add -.sp - --enable-utf8 -.sp -to the \fBconfigure\fP command. Of itself, this does not make PCRE treat -strings as UTF-8. As well as compiling PCRE with this option, you also have -have to set the PCRE_UTF8 option when you call the \fBpcre_compile()\fP -function. -. -.SH "UNICODE CHARACTER PROPERTY SUPPORT" -.rs -.sp -UTF-8 support allows PCRE to process character values greater than 255 in the -strings that it handles. On its own, however, it does not provide any -facilities for accessing the properties of such characters. If you want to be -able to use the pattern escapes \eP, \ep, and \eX, which refer to Unicode -character properties, you must add -.sp - --enable-unicode-properties -.sp -to the \fBconfigure\fP command. This implies UTF-8 support, even if you have -not explicitly requested it. -.P -Including Unicode property support adds around 90K of tables to the PCRE -library, approximately doubling its size. Only the general category properties -such as \fILu\fP and \fINd\fP are supported. Details are given in the -.\" HREF -\fBpcrepattern\fP -.\" -documentation. -. -.SH "CODE VALUE OF NEWLINE" -.rs -.sp -By default, PCRE treats character 10 (linefeed) as the newline character. This -is the normal newline character on Unix-like systems. You can compile PCRE to -use character 13 (carriage return) instead by adding -.sp - --enable-newline-is-cr -.sp -to the \fBconfigure\fP command. For completeness there is also a ---enable-newline-is-lf option, which explicitly specifies linefeed as the -newline character. -. -.SH "BUILDING SHARED AND STATIC LIBRARIES" -.rs -.sp -The PCRE building process uses \fBlibtool\fP to build both shared and static -Unix libraries by default. You can suppress one of these by adding one of -.sp - --disable-shared - --disable-static -.sp -to the \fBconfigure\fP command, as required. -. -.SH "POSIX MALLOC USAGE" -.rs -.sp -When PCRE is called through the POSIX interface (see the -.\" HREF -\fBpcreposix\fP -.\" -documentation), additional working storage is required for holding the pointers -to capturing substrings, because PCRE requires three integers per substring, -whereas the POSIX interface provides only two. If the number of expected -substrings is small, the wrapper function uses space on the stack, because this -is faster than using \fBmalloc()\fP for each call. The default threshold above -which the stack is no longer used is 10; it can be changed by adding a setting -such as -.sp - --with-posix-malloc-threshold=20 -.sp -to the \fBconfigure\fP command. -. -.SH "LIMITING PCRE RESOURCE USAGE" -.rs -.sp -Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly -(possibly recursively) when matching a pattern. By controlling the maximum -number of times this function may be called during a single matching operation, -a limit can be placed on the resources used by a single call to -\fBpcre_exec()\fP. The limit can be changed at run time, as described in the -.\" HREF -\fBpcreapi\fP -.\" -documentation. The default is 10 million, but this can be changed by adding a -setting such as -.sp - --with-match-limit=500000 -.sp -to the \fBconfigure\fP command. -. -.SH "HANDLING VERY LARGE PATTERNS" -.rs -.sp -Within a compiled pattern, offset values are used to point from one part to -another (for example, from an opening parenthesis to an alternation -metacharacter). By default, two-byte values are used for these offsets, leading -to a maximum size for a compiled pattern of around 64K. This is sufficient to -handle all but the most gigantic patterns. Nevertheless, some people do want to -process enormous patterns, so it is possible to compile PCRE to use three-byte -or four-byte offsets by adding a setting such as -.sp - --with-link-size=3 -.sp -to the \fBconfigure\fP command. The value given must be 2, 3, or 4. Using -longer offsets slows down the operation of PCRE because it has to load -additional bytes when handling them. -.P -If you build PCRE with an increased link size, test 2 (and test 5 if you are -using UTF-8) will fail. Part of the output of these tests is a representation -of the compiled pattern, and this changes with the link size. -. -.SH "AVOIDING EXCESSIVE STACK USAGE" -.rs -.sp -PCRE implements backtracking while matching by making recursive calls to an -internal function called \fBmatch()\fP. In environments where the size of the -stack is limited, this can severely limit PCRE's operation. (The Unix -environment does not usually suffer from this problem.) An alternative approach -that uses memory from the heap to remember data, instead of using recursive -function calls, has been implemented to work round this problem. If you want to -build a version of PCRE that works this way, add -.sp - --disable-stack-for-recursion -.sp -to the \fBconfigure\fP command. With this configuration, PCRE will use the -\fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP variables to call memory -management functions. Separate functions are provided because the usage is very -predictable: the block sizes requested are always the same, and the blocks are -always freed in reverse order. A calling program might be able to implement -optimized functions that perform better than the standard \fBmalloc()\fP and -\fBfree()\fP functions. PCRE runs noticeably more slowly when built in this -way. -. -.SH "USING EBCDIC CODE" -.rs -.sp -PCRE assumes by default that it will run in an environment where the character -code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be -compiled to run in an EBCDIC environment by adding -.sp - --enable-ebcdic -.sp -to the \fBconfigure\fP command. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcrecallout.3 b/srclib/pcre/doc/pcrecallout.3 deleted file mode 100644 index 5fd8ff8712..0000000000 --- a/srclib/pcre/doc/pcrecallout.3 +++ /dev/null @@ -1,155 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PCRE CALLOUTS" -.rs -.sp -.B int (*pcre_callout)(pcre_callout_block *); -.PP -PCRE provides a feature called "callout", which is a means of temporarily -passing control to the caller of PCRE in the middle of pattern matching. The -caller of PCRE provides an external function by putting its entry point in the -global variable \fIpcre_callout\fP. By default, this variable contains NULL, -which disables all calling out. -.P -Within a regular expression, (?C) indicates the points at which the external -function is to be called. Different callout points can be identified by putting -a number less than 256 after the letter C. The default value is zero. -For example, this pattern has two callout points: -.sp - (?C1)\deabc(?C2)def -.sp -If the PCRE_AUTO_CALLOUT option bit is set when \fBpcre_compile()\fP is called, -PCRE automatically inserts callouts, all with number 255, before each item in -the pattern. For example, if PCRE_AUTO_CALLOUT is used with the pattern -.sp - A(\ed{2}|--) -.sp -it is processed as if it were -.sp -(?C255)A(?C255)((?C255)\ed{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255) -.sp -Notice that there is a callout before and after each parenthesis and -alternation bar. Automatic callouts can be used for tracking the progress of -pattern matching. The -.\" HREF -\fBpcretest\fP -.\" -command has an option that sets automatic callouts; when it is used, the output -indicates how the pattern is matched. This is useful information when you are -trying to optimize the performance of a particular pattern. -. -. -.SH "MISSING CALLOUTS" -.rs -.sp -You should be aware that, because of optimizations in the way PCRE matches -patterns, callouts sometimes do not happen. For example, if the pattern is -.sp - ab(?C4)cd -.sp -PCRE knows that any matching string must contain the letter "d". If the subject -string is "abyz", the lack of "d" means that matching doesn't ever start, and -the callout is never reached. However, with "abyd", though the result is still -no match, the callout is obeyed. -. -. -.SH "THE CALLOUT INTERFACE" -.rs -.sp -During matching, when PCRE reaches a callout point, the external function -defined by \fIpcre_callout\fP is called (if it is set). The only argument is a -pointer to a \fBpcre_callout\fP block. This structure contains the following -fields: -.sp - int \fIversion\fP; - int \fIcallout_number\fP; - int *\fIoffset_vector\fP; - const char *\fIsubject\fP; - int \fIsubject_length\fP; - int \fIstart_match\fP; - int \fIcurrent_position\fP; - int \fIcapture_top\fP; - int \fIcapture_last\fP; - void *\fIcallout_data\fP; - int \fIpattern_position\fP; - int \fInext_item_length\fP; -.sp -The \fIversion\fP field is an integer containing the version number of the -block format. The initial version was 0; the current version is 1. The version -number will change again in future if additional fields are added, but the -intention is never to remove any of the existing fields. -.P -The \fIcallout_number\fP field contains the number of the callout, as compiled -into the pattern (that is, the number after ?C for manual callouts, and 255 for -automatically generated callouts). -.P -The \fIoffset_vector\fP field is a pointer to the vector of offsets that was -passed by the caller to \fBpcre_exec()\fP. The contents can be inspected in -order to extract substrings that have been matched so far, in the same way as -for extracting substrings after a match has completed. -.P -The \fIsubject\fP and \fIsubject_length\fP fields contain copies of the values -that were passed to \fBpcre_exec()\fP. -.P -The \fIstart_match\fP field contains the offset within the subject at which the -current match attempt started. If the pattern is not anchored, the callout -function may be called several times from the same point in the pattern for -different starting points in the subject. -.P -The \fIcurrent_position\fP field contains the offset within the subject of the -current match pointer. -.P -The \fIcapture_top\fP field contains one more than the number of the highest -numbered captured substring so far. If no substrings have been captured, -the value of \fIcapture_top\fP is one. -.P -The \fIcapture_last\fP field contains the number of the most recently captured -substring. If no substrings have been captured, its value is -1. -.P -The \fIcallout_data\fP field contains a value that is passed to -\fBpcre_exec()\fP by the caller specifically so that it can be passed back in -callouts. It is passed in the \fIpcre_callout\fP field of the \fBpcre_extra\fP -data structure. If no such data was passed, the value of \fIcallout_data\fP in -a \fBpcre_callout\fP block is NULL. There is a description of the -\fBpcre_extra\fP structure in the -.\" HREF -\fBpcreapi\fP -.\" -documentation. -.P -The \fIpattern_position\fP field is present from version 1 of the -\fIpcre_callout\fP structure. It contains the offset to the next item to be -matched in the pattern string. -.P -The \fInext_item_length\fP field is present from version 1 of the -\fIpcre_callout\fP structure. It contains the length of the next item to be -matched in the pattern string. When the callout immediately precedes an -alternation bar, a closing parenthesis, or the end of the pattern, the length -is zero. When the callout precedes an opening parenthesis, the length is that -of the entire subpattern. -.P -The \fIpattern_position\fP and \fInext_item_length\fP fields are intended to -help in distinguishing between different automatic callouts, which all have the -same callout number. However, they are set for all callouts. -. -. -.SH "RETURN VALUES" -.rs -.sp -The external callout function returns an integer to PCRE. If the value is zero, -matching proceeds as normal. If the value is greater than zero, matching fails -at the current point, but backtracking to test other matching possibilities -goes ahead, just as if a lookahead assertion had failed. If the value is less -than zero, the match is abandoned, and \fBpcre_exec()\fP returns the negative -value. -.P -Negative values should normally be chosen from the set of PCRE_ERROR_xxx -values. In particular, PCRE_ERROR_NOMATCH forces a standard "no match" failure. -The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions; -it will never be used by PCRE itself. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcrecompat.3 b/srclib/pcre/doc/pcrecompat.3 deleted file mode 100644 index 6a853e072a..0000000000 --- a/srclib/pcre/doc/pcrecompat.3 +++ /dev/null @@ -1,121 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "DIFFERENCES BETWEEN PCRE AND PERL" -.rs -.sp -This document describes the differences in the ways that PCRE and Perl handle -regular expressions. The differences described here are with respect to Perl -5.8. -.P -1. PCRE does not have full UTF-8 support. Details of what it does have are -given in the -.\" HTML -.\" -section on UTF-8 support -.\" -in the main -.\" HREF -\fBpcre\fP -.\" -page. -.P -2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits -them, but they do not mean what you might think. For example, (?!a){3} does -not assert that the next three characters are not "a". It just asserts that the -next character is not "a" three times. -.P -3. Capturing subpatterns that occur inside negative lookahead assertions are -counted, but their entries in the offsets vector are never set. Perl sets its -numerical variables from any such patterns that are matched before the -assertion fails to match something (thereby succeeding), but only if the -negative lookahead assertion contains just one branch. -.P -4. Though binary zero characters are supported in the subject string, they are -not allowed in a pattern string because it is passed as a normal C string, -terminated by zero. The escape sequence \e0 can be used in the pattern to -represent a binary zero. -.P -5. The following Perl escape sequences are not supported: \el, \eu, \eL, -\eU, and \eN. In fact these are implemented by Perl's general string-handling -and are not part of its pattern matching engine. If any of these are -encountered by PCRE, an error is generated. -.P -6. The Perl escape sequences \ep, \eP, and \eX are supported only if PCRE is -built with Unicode character property support. The properties that can be -tested with \ep and \eP are limited to the general category properties such as -Lu and Nd. -.P -7. PCRE does support the \eQ...\eE escape for quoting substrings. Characters in -between are treated as literals. This is slightly different from Perl in that $ -and @ are also handled as literals inside the quotes. In Perl, they cause -variable interpolation (but of course PCRE does not have variables). Note the -following examples: -.sp - Pattern PCRE matches Perl matches -.sp -.\" JOIN - \eQabc$xyz\eE abc$xyz abc followed by the - contents of $xyz - \eQabc\e$xyz\eE abc\e$xyz abc\e$xyz - \eQabc\eE\e$\eQxyz\eE abc$xyz abc$xyz -.sp -The \eQ...\eE sequence is recognized both inside and outside character classes. -.P -8. Fairly obviously, PCRE does not support the (?{code}) and (?p{code}) -constructions. However, there is support for recursive patterns using the -non-Perl items (?R), (?number), and (?P>name). Also, the PCRE "callout" feature -allows an external function to be called during pattern matching. See the -.\" HREF -\fBpcrecallout\fP -.\" -documentation for details. -.P -9. There are some differences that are concerned with the settings of captured -strings when part of a pattern is repeated. For example, matching "aba" against -the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b". -.P -10. PCRE provides some extensions to the Perl regular expression facilities: -.sp -(a) Although lookbehind assertions must match fixed length strings, each -alternative branch of a lookbehind assertion can match a different length of -string. Perl requires them all to have the same length. -.sp -(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ -meta-character matches only at the very end of the string. -.sp -(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special -meaning is faulted. -.sp -(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is -inverted, that is, by default they are not greedy, but if followed by a -question mark they are. -.sp -(e) PCRE_ANCHORED can be used at matching time to force a pattern to be tried -only at the first matching position in the subject string. -.sp -(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAPTURE -options for \fBpcre_exec()\fP have no Perl equivalents. -.sp -(g) The (?R), (?number), and (?P>name) constructs allows for recursive pattern -matching (Perl can do this using the (?p{code}) construct, which PCRE cannot -support.) -.sp -(h) PCRE supports named capturing substrings, using the Python syntax. -.sp -(i) PCRE supports the possessive quantifier "++" syntax, taken from Sun's Java -package. -.sp -(j) The (R) condition, for testing recursion, is a PCRE extension. -.sp -(k) The callout facility is PCRE-specific. -.sp -(l) The partial matching facility is PCRE-specific. -.sp -(m) Patterns compiled by PCRE can be saved and re-used at a later time, even on -different hosts that have the other endianness. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcregrep.1 b/srclib/pcre/doc/pcregrep.1 deleted file mode 100644 index 56c37d8725..0000000000 --- a/srclib/pcre/doc/pcregrep.1 +++ /dev/null @@ -1,130 +0,0 @@ -.TH PCREGREP 1 -.SH NAME -pcregrep - a grep with Perl-compatible regular expressions. -.SH SYNOPSIS -.B pcregrep [-Vcfhilnrsuvx] [long options] [pattern] [file1 file2 ...] -. -.SH DESCRIPTION -.rs -.sp -\fBpcregrep\fP searches files for character patterns, in the same way as other -grep commands do, but it uses the PCRE regular expression library to support -patterns that are compatible with the regular expressions of Perl 5. See -.\" HREF -\fBpcrepattern\fP -.\" -for a full description of syntax and semantics of the regular expressions that -PCRE supports. -.P -A pattern must be specified on the command line unless the \fB-f\fP option is -used (see below). -.P -If no files are specified, \fBpcregrep\fP reads the standard input. By default, -each line that matches the pattern is copied to the standard output, and if -there is more than one file, the file name is printed before each line of -output. However, there are options that can change how \fBpcregrep\fP behaves. -.P -Lines are limited to BUFSIZ characters. BUFSIZ is defined in \fB\fP. -The newline character is removed from the end of each line before it is matched -against the pattern. -. -.SH OPTIONS -.rs -.sp -.TP 10 -\fB-V\fP -Write the version number of the PCRE library being used to the standard error -stream. -.TP -\fB-c\fP -Do not print individual lines; instead just print a count of the number of -lines that would otherwise have been printed. If several files are given, a -count is printed for each of them. -.TP -\fB-f\fP\fIfilename\fP -Read a number of patterns from the file, one per line, and match all of them -against each line of input. A line is output if any of the patterns match it. -When \fB-f\fP is used, no pattern is taken from the command line; all arguments -are treated as file names. There is a maximum of 100 patterns. Trailing white -space is removed, and blank lines are ignored. An empty file contains no -patterns and therefore matches nothing. -.TP -\fB-h\fP -Suppress printing of filenames when searching multiple files. -.TP -\fB-i\fP -Ignore upper/lower case distinctions during comparisons. -.TP -\fB-l\fP -Instead of printing lines from the files, just print the names of the files -containing lines that would have been printed. Each file name is printed -once, on a separate line. -.TP -\fB-n\fP -Precede each line by its line number in the file. -.TP -\fB-r\fP -If any file is a directory, recursively scan the files it contains. Without -\fB-r\fP a directory is scanned as a normal file. -.TP -\fB-s\fP -Work silently, that is, display nothing except error messages. -The exit status indicates whether any matches were found. -.TP -\fB-u\fP -Operate in UTF-8 mode. This option is available only if PCRE has been compiled -with UTF-8 support. Both the pattern and each subject line must be valid -strings of UTF-8 characters. -.TP -\fB-v\fP -Invert the sense of the match, so that lines which do \fInot\fP match the -pattern are now the ones that are found. -.TP -\fB-x\fP -Force the pattern to be anchored (it must start matching at the beginning of -the line) and in addition, require it to match the entire line. This is -equivalent to having ^ and $ characters at the start and end of each -alternative branch in the regular expression. -. -.SH "LONG OPTIONS" -.rs -.sp -Long forms of all the options are available, as in GNU grep. They are shown in -the following table: -.sp - -c --count - -h --no-filename - -i --ignore-case - -l --files-with-matches - -n --line-number - -r --recursive - -s --no-messages - -u --utf-8 - -V --version - -v --invert-match - -x --line-regex - -x --line-regexp -.sp -In addition, --file=\fIfilename\fP is equivalent to -f\fIfilename\fP, and ---help shows the list of options and then exits. -. -.SH DIAGNOSTICS -.rs -.sp -Exit status is 0 if any matches were found, 1 if no matches were found, and 2 -for syntax errors or inacessible files (even if matches were found). -. -. -.SH AUTHOR -.rs -.sp -Philip Hazel -.br -University Computing Service -.br -Cambridge CB2 3QG, England. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcregrep.html b/srclib/pcre/doc/pcregrep.html deleted file mode 100644 index 7bc210c65a..0000000000 --- a/srclib/pcre/doc/pcregrep.html +++ /dev/null @@ -1,120 +0,0 @@ - - -pcregrep specification - - -

    pcregrep specification

    -This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page in case the -conversion went wrong. - -
  • NAME -

    -pcregrep - a grep with Perl-compatible regular expressions. -

    -
  • SYNOPSIS -

    -pcregrep [-Vcfhilnrsvx] pattern [file] ... -

    -
  • DESCRIPTION -

    -pcregrep searches files for character patterns, in the same way as other -grep commands do, but it uses the PCRE regular expression library to support -patterns that are compatible with the regular expressions of Perl 5. See -pcre(3) for a full description of syntax and semantics. -

    -

    -If no files are specified, pcregrep reads the standard input. By default, -each line that matches the pattern is copied to the standard output, and if -there is more than one file, the file name is printed before each line of -output. However, there are options that can change how pcregrep behaves. -

    -

    -Lines are limited to BUFSIZ characters. BUFSIZ is defined in <stdio.h>. -The newline character is removed from the end of each line before it is matched -against the pattern. -

    -
  • OPTIONS -

    --V -Write the version number of the PCRE library being used to the standard error -stream. -

    -

    --c -Do not print individual lines; instead just print a count of the number of -lines that would otherwise have been printed. If several files are given, a -count is printed for each of them. -

    -

    -\fB-ffilename -Read patterns from the file, one per line, and match all patterns against each -line. There is a maximum of 100 patterns. Trailing white space is removed, and -blank lines are ignored. An empty file contains no patterns and therefore -matches nothing. -

    -

    --h -Suppress printing of filenames when searching multiple files. -

    -

    --i -Ignore upper/lower case distinctions during comparisons. -

    -

    --l -Instead of printing lines from the files, just print the names of the files -containing lines that would have been printed. Each file name is printed -once, on a separate line. -

    -

    --n -Precede each line by its line number in the file. -

    -

    --r -If any file is a directory, recursively scan the files it contains. Without --r a directory is scanned as a normal file. -

    -

    --s -Work silently, that is, display nothing except error messages. -The exit status indicates whether any matches were found. -

    -

    --v -Invert the sense of the match, so that lines which do not match the -pattern are now the ones that are found. -

    -

    --x -Force the pattern to be anchored (it must start matching at the beginning of -the line) and in addition, require it to match the entire line. This is -equivalent to having ^ and $ characters at the start and end of each -alternative branch in the regular expression. -

    -
  • SEE ALSO -

    -pcre(3), Perl 5 documentation -

    -
  • DIAGNOSTICS -

    -Exit status is 0 if any matches were found, 1 if no matches were found, and 2 -for syntax errors or inacessible files (even if matches were found). -

    -
  • AUTHOR -

    -Philip Hazel <ph10@cam.ac.uk> -

    -

    -Last updated: 15 August 2001 -
    -Copyright (c) 1997-2001 University of Cambridge. diff --git a/srclib/pcre/doc/pcregrep.txt b/srclib/pcre/doc/pcregrep.txt deleted file mode 100644 index 1dca003c8b..0000000000 --- a/srclib/pcre/doc/pcregrep.txt +++ /dev/null @@ -1,122 +0,0 @@ -PCREGREP(1) PCREGREP(1) - - - -NAME - pcregrep - a grep with Perl-compatible regular expressions. - -SYNOPSIS - pcregrep [-Vcfhilnrsuvx] [long options] [pattern] [file1 file2 ...] - - -DESCRIPTION - - pcregrep searches files for character patterns, in the same way as - other grep commands do, but it uses the PCRE regular expression library - to support patterns that are compatible with the regular expressions of - Perl 5. See pcrepattern for a full description of syntax and semantics - of the regular expressions that PCRE supports. - - A pattern must be specified on the command line unless the -f option is - used (see below). - - If no files are specified, pcregrep reads the standard input. By - default, each line that matches the pattern is copied to the standard - output, and if there is more than one file, the file name is printed - before each line of output. However, there are options that can change - how pcregrep behaves. - - Lines are limited to BUFSIZ characters. BUFSIZ is defined in . - The newline character is removed from the end of each line before it is - matched against the pattern. - - -OPTIONS - - - -V Write the version number of the PCRE library being used to - the standard error stream. - - -c Do not print individual lines; instead just print a count of - the number of lines that would otherwise have been printed. - If several files are given, a count is printed for each of - them. - - -ffilename - Read a number of patterns from the file, one per line, and - match all of them against each line of input. A line is out- - put if any of the patterns match it. When -f is used, no - pattern is taken from the command line; all arguments are - treated as file names. There is a maximum of 100 patterns. - Trailing white space is removed, and blank lines are ignored. - An empty file contains no patterns and therefore matches - nothing. - - -h Suppress printing of filenames when searching multiple files. - - -i Ignore upper/lower case distinctions during comparisons. - - -l Instead of printing lines from the files, just print the - names of the files containing lines that would have been - printed. Each file name is printed once, on a separate line. - - -n Precede each line by its line number in the file. - - -r If any file is a directory, recursively scan the files it - contains. Without -r a directory is scanned as a normal file. - - -s Work silently, that is, display nothing except error mes- - sages. The exit status indicates whether any matches were - found. - - -u Operate in UTF-8 mode. This option is available only if PCRE - has been compiled with UTF-8 support. Both the pattern and - each subject line must be valid strings of UTF-8 characters. - - -v Invert the sense of the match, so that lines which do not - match the pattern are now the ones that are found. - - -x Force the pattern to be anchored (it must start matching at - the beginning of the line) and in addition, require it to - match the entire line. This is equivalent to having ^ and $ - characters at the start and end of each alternative branch in - the regular expression. - - -LONG OPTIONS - - Long forms of all the options are available, as in GNU grep. They are - shown in the following table: - - -c --count - -h --no-filename - -i --ignore-case - -l --files-with-matches - -n --line-number - -r --recursive - -s --no-messages - -u --utf-8 - -V --version - -v --invert-match - -x --line-regex - -x --line-regexp - - In addition, --file=filename is equivalent to -ffilename, and --help - shows the list of options and then exits. - - -DIAGNOSTICS - - Exit status is 0 if any matches were found, 1 if no matches were found, - and 2 for syntax errors or inacessible files (even if matches were - found). - - -AUTHOR - - Philip Hazel - University Computing Service - Cambridge CB2 3QG, England. - -Last updated: 09 September 2004 -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcrepartial.3 b/srclib/pcre/doc/pcrepartial.3 deleted file mode 100644 index 3489c18195..0000000000 --- a/srclib/pcre/doc/pcrepartial.3 +++ /dev/null @@ -1,95 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PARTIAL MATCHING IN PCRE" -.rs -.sp -In normal use of PCRE, if the subject string that is passed to -\fBpcre_exec()\fP matches as far as it goes, but is too short to match the -entire pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances where -it might be helpful to distinguish this case from other cases in which there is -no match. -.P -Consider, for example, an application where a human is required to type in data -for a field with specific formatting requirements. An example might be a date -in the form \fIddmmmyy\fP, defined by this pattern: -.sp - ^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$ -.sp -If the application sees the user's keystrokes one by one, and can check that -what has been typed so far is potentially valid, it is able to raise an error -as soon as a mistake is made, possibly beeping and not reflecting the -character that has been typed. This immediate feedback is likely to be a better -user interface than a check that is delayed until the entire string has been -entered. -.P -PCRE supports the concept of partial matching by means of the PCRE_PARTIAL -option, which can be set when calling \fBpcre_exec()\fP. When this is done, the -return code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if at any -time during the matching process the entire subject string matched part of the -pattern. No captured data is set when this occurs. -.P -Using PCRE_PARTIAL disables one of PCRE's optimizations. PCRE remembers the -last literal byte in a pattern, and abandons matching immediately if such a -byte is not present in the subject string. This optimization cannot be used -for a subject string that might match only partially. -. -. -.SH "RESTRICTED PATTERNS FOR PCRE_PARTIAL" -.rs -.sp -Because of the way certain internal optimizations are implemented in PCRE, the -PCRE_PARTIAL option cannot be used with all patterns. Repeated single -characters such as -.sp - a{2,4} -.sp -and repeated single metasequences such as -.sp - \ed+ -.sp -are not permitted if the maximum number of occurrences is greater than one. -Optional items such as \ed? (where the maximum is one) are permitted. -Quantifiers with any values are permitted after parentheses, so the invalid -examples above can be coded thus: -.sp - (a){2,4} - (\ed)+ -.sp -These constructions run more slowly, but for the kinds of application that are -envisaged for this facility, this is not felt to be a major restriction. -.P -If PCRE_PARTIAL is set for a pattern that does not conform to the restrictions, -\fBpcre_exec()\fP returns the error code PCRE_ERROR_BADPARTIAL (-13). -. -. -.SH "EXAMPLE OF PARTIAL MATCHING USING PCRETEST" -.rs -.sp -If the escape sequence \eP is present in a \fBpcretest\fP data line, the -PCRE_PARTIAL flag is used for the match. Here is a run of \fBpcretest\fP that -uses the date example quoted above: -.sp - re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/ - data> 25jun04\P - 0: 25jun04 - 1: jun - data> 25dec3\P - Partial match - data> 3ju\P - Partial match - data> 3juj\P - No match - data> j\P - No match -.sp -The first data string is matched completely, so \fBpcretest\fP shows the -matched substrings. The remaining four strings do not match the complete -pattern, but the first two are partial matches. -. -. -.P -.in 0 -Last updated: 08 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcrepattern.3 b/srclib/pcre/doc/pcrepattern.3 deleted file mode 100644 index 6f6a21ab1a..0000000000 --- a/srclib/pcre/doc/pcrepattern.3 +++ /dev/null @@ -1,1456 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PCRE REGULAR EXPRESSION DETAILS" -.rs -.sp -The syntax and semantics of the regular expressions supported by PCRE are -described below. Regular expressions are also described in the Perl -documentation and in a number of books, some of which have copious examples. -Jeffrey Friedl's "Mastering Regular Expressions", published by O'Reilly, covers -regular expressions in great detail. This description of PCRE's regular -expressions is intended as reference material. -.P -The original operation of PCRE was on strings of one-byte characters. However, -there is now also support for UTF-8 character strings. To use this, you must -build PCRE to include UTF-8 support, and then call \fBpcre_compile()\fP with -the PCRE_UTF8 option. How this affects pattern matching is mentioned in several -places below. There is also a summary of UTF-8 features in the -.\" HTML -.\" -section on UTF-8 support -.\" -in the main -.\" HREF -\fBpcre\fP -.\" -page. -.P -A regular expression is a pattern that is matched against a subject string from -left to right. Most characters stand for themselves in a pattern, and match the -corresponding characters in the subject. As a trivial example, the pattern -.sp - The quick brown fox -.sp -matches a portion of a subject string that is identical to itself. The power of -regular expressions comes from the ability to include alternatives and -repetitions in the pattern. These are encoded in the pattern by the use of -\fImetacharacters\fP, which do not stand for themselves but instead are -interpreted in some special way. -.P -There are two different sets of metacharacters: those that are recognized -anywhere in the pattern except within square brackets, and those that are -recognized in square brackets. Outside square brackets, the metacharacters are -as follows: -.sp - \e general escape character with several uses - ^ assert start of string (or line, in multiline mode) - $ assert end of string (or line, in multiline mode) - . match any character except newline (by default) - [ start character class definition - | start of alternative branch - ( start subpattern - ) end subpattern - ? extends the meaning of ( - also 0 or 1 quantifier - also quantifier minimizer - * 0 or more quantifier - + 1 or more quantifier - also "possessive quantifier" - { start min/max quantifier -.sp -Part of a pattern that is in square brackets is called a "character class". In -a character class the only metacharacters are: -.sp - \e general escape character - ^ negate the class, but only if the first character - - indicates character range -.\" JOIN - [ POSIX character class (only if followed by POSIX - syntax) - ] terminates the character class -.sp -The following sections describe the use of each of the metacharacters. -. -.SH BACKSLASH -.rs -.sp -The backslash character has several uses. Firstly, if it is followed by a -non-alphanumeric character, it takes away any special meaning that character may -have. This use of backslash as an escape character applies both inside and -outside character classes. -.P -For example, if you want to match a * character, you write \e* in the pattern. -This escaping action applies whether or not the following character would -otherwise be interpreted as a metacharacter, so it is always safe to precede a -non-alphanumeric with backslash to specify that it stands for itself. In -particular, if you want to match a backslash, you write \e\e. -.P -If a pattern is compiled with the PCRE_EXTENDED option, whitespace in the -pattern (other than in a character class) and characters between a # outside -a character class and the next newline character are ignored. An escaping -backslash can be used to include a whitespace or # character as part of the -pattern. -.P -If you want to remove the special meaning from a sequence of characters, you -can do so by putting them between \eQ and \eE. This is different from Perl in -that $ and @ are handled as literals in \eQ...\eE sequences in PCRE, whereas in -Perl, $ and @ cause variable interpolation. Note the following examples: -.sp - Pattern PCRE matches Perl matches -.sp -.\" JOIN - \eQabc$xyz\eE abc$xyz abc followed by the - contents of $xyz - \eQabc\e$xyz\eE abc\e$xyz abc\e$xyz - \eQabc\eE\e$\eQxyz\eE abc$xyz abc$xyz -.sp -The \eQ...\eE sequence is recognized both inside and outside character classes. -. -. -.\" HTML -.SS "Non-printing characters" -.rs -.sp -A second use of backslash provides a way of encoding non-printing characters -in patterns in a visible manner. There is no restriction on the appearance of -non-printing characters, apart from the binary zero that terminates a pattern, -but when a pattern is being prepared by text editing, it is usually easier to -use one of the following escape sequences than the binary character it -represents: -.sp - \ea alarm, that is, the BEL character (hex 07) - \ecx "control-x", where x is any character - \ee escape (hex 1B) - \ef formfeed (hex 0C) - \en newline (hex 0A) - \er carriage return (hex 0D) - \et tab (hex 09) - \eddd character with octal code ddd, or backreference - \exhh character with hex code hh - \ex{hhh..} character with hex code hhh... (UTF-8 mode only) -.sp -The precise effect of \ecx is as follows: if x is a lower case letter, it -is converted to upper case. Then bit 6 of the character (hex 40) is inverted. -Thus \ecz becomes hex 1A, but \ec{ becomes hex 3B, while \ec; becomes hex -7B. -.P -After \ex, from zero to two hexadecimal digits are read (letters can be in -upper or lower case). In UTF-8 mode, any number of hexadecimal digits may -appear between \ex{ and }, but the value of the character code must be less -than 2**31 (that is, the maximum hexadecimal value is 7FFFFFFF). If characters -other than hexadecimal digits appear between \ex{ and }, or if there is no -terminating }, this form of escape is not recognized. Instead, the initial -\ex will be interpreted as a basic hexadecimal escape, with no following -digits, giving a character whose value is zero. -.P -Characters whose value is less than 256 can be defined by either of the two -syntaxes for \ex when PCRE is in UTF-8 mode. There is no difference in the -way they are handled. For example, \exdc is exactly the same as \ex{dc}. -.P -After \e0 up to two further octal digits are read. In both cases, if there -are fewer than two digits, just those that are present are used. Thus the -sequence \e0\ex\e07 specifies two binary zeros followed by a BEL character -(code value 7). Make sure you supply two digits after the initial zero if the -pattern character that follows is itself an octal digit. -.P -The handling of a backslash followed by a digit other than 0 is complicated. -Outside a character class, PCRE reads it and any following digits as a decimal -number. If the number is less than 10, or if there have been at least that many -previous capturing left parentheses in the expression, the entire sequence is -taken as a \fIback reference\fP. A description of how this works is given -.\" HTML -.\" -later, -.\" -following the discussion of -.\" HTML -.\" -parenthesized subpatterns. -.\" -.P -Inside a character class, or if the decimal number is greater than 9 and there -have not been that many capturing subpatterns, PCRE re-reads up to three octal -digits following the backslash, and generates a single byte from the least -significant 8 bits of the value. Any subsequent digits stand for themselves. -For example: -.sp - \e040 is another way of writing a space -.\" JOIN - \e40 is the same, provided there are fewer than 40 - previous capturing subpatterns - \e7 is always a back reference -.\" JOIN - \e11 might be a back reference, or another way of - writing a tab - \e011 is always a tab - \e0113 is a tab followed by the character "3" -.\" JOIN - \e113 might be a back reference, otherwise the - character with octal code 113 -.\" JOIN - \e377 might be a back reference, otherwise - the byte consisting entirely of 1 bits -.\" JOIN - \e81 is either a back reference, or a binary zero - followed by the two characters "8" and "1" -.sp -Note that octal values of 100 or greater must not be introduced by a leading -zero, because no more than three octal digits are ever read. -.P -All the sequences that define a single byte value or a single UTF-8 character -(in UTF-8 mode) can be used both inside and outside character classes. In -addition, inside a character class, the sequence \eb is interpreted as the -backspace character (hex 08), and the sequence \eX is interpreted as the -character "X". Outside a character class, these sequences have different -meanings -.\" HTML -.\" -(see below). -.\" -. -. -.SS "Generic character types" -.rs -.sp -The third use of backslash is for specifying generic character types. The -following are always recognized: -.sp - \ed any decimal digit - \eD any character that is not a decimal digit - \es any whitespace character - \eS any character that is not a whitespace character - \ew any "word" character - \eW any "non-word" character -.sp -Each pair of escape sequences partitions the complete set of characters into -two disjoint sets. Any given character matches one, and only one, of each pair. -.P -These character type sequences can appear both inside and outside character -classes. They each match one character of the appropriate type. If the current -matching point is at the end of the subject string, all of them fail, since -there is no character to match. -.P -For compatibility with Perl, \es does not match the VT character (code 11). -This makes it different from the the POSIX "space" class. The \es characters -are HT (9), LF (10), FF (12), CR (13), and space (32). -.P -A "word" character is an underscore or any character less than 256 that is a -letter or digit. The definition of letters and digits is controlled by PCRE's -low-valued character tables, and may vary if locale-specific matching is taking -place (see -.\" HTML -.\" -"Locale support" -.\" -in the -.\" HREF -\fBpcreapi\fP -.\" -page). For example, in the "fr_FR" (French) locale, some character codes -greater than 128 are used for accented letters, and these are matched by \ew. -.P -In UTF-8 mode, characters with values greater than 128 never match \ed, \es, or -\ew, and always match \eD, \eS, and \eW. This is true even when Unicode -character property support is available. -. -. -.\" HTML -.SS Unicode character properties -.rs -.sp -When PCRE is built with Unicode character property support, three additional -escape sequences to match generic character types are available when UTF-8 mode -is selected. They are: -.sp - \ep{\fIxx\fP} a character with the \fIxx\fP property - \eP{\fIxx\fP} a character without the \fIxx\fP property - \eX an extended Unicode sequence -.sp -The property names represented by \fIxx\fP above are limited to the -Unicode general category properties. Each character has exactly one such -property, specified by a two-letter abbreviation. For compatibility with Perl, -negation can be specified by including a circumflex between the opening brace -and the property name. For example, \ep{^Lu} is the same as \eP{Lu}. -.P -If only one letter is specified with \ep or \eP, it includes all the properties -that start with that letter. In this case, in the absence of negation, the -curly brackets in the escape sequence are optional; these two examples have -the same effect: -.sp - \ep{L} - \epL -.sp -The following property codes are supported: -.sp - C Other - Cc Control - Cf Format - Cn Unassigned - Co Private use - Cs Surrogate -.sp - L Letter - Ll Lower case letter - Lm Modifier letter - Lo Other letter - Lt Title case letter - Lu Upper case letter -.sp - M Mark - Mc Spacing mark - Me Enclosing mark - Mn Non-spacing mark -.sp - N Number - Nd Decimal number - Nl Letter number - No Other number -.sp - P Punctuation - Pc Connector punctuation - Pd Dash punctuation - Pe Close punctuation - Pf Final punctuation - Pi Initial punctuation - Po Other punctuation - Ps Open punctuation -.sp - S Symbol - Sc Currency symbol - Sk Modifier symbol - Sm Mathematical symbol - So Other symbol -.sp - Z Separator - Zl Line separator - Zp Paragraph separator - Zs Space separator -.sp -Extended properties such as "Greek" or "InMusicalSymbols" are not supported by -PCRE. -.P -Specifying caseless matching does not affect these escape sequences. For -example, \ep{Lu} always matches only upper case letters. -.P -The \eX escape matches any number of Unicode characters that form an extended -Unicode sequence. \eX is equivalent to -.sp - (?>\ePM\epM*) -.sp -That is, it matches a character without the "mark" property, followed by zero -or more characters with the "mark" property, and treats the sequence as an -atomic group -.\" HTML -.\" -(see below). -.\" -Characters with the "mark" property are typically accents that affect the -preceding character. -.P -Matching characters by Unicode property is not fast, because PCRE has to search -a structure that contains data for over fifteen thousand characters. That is -why the traditional escape sequences such as \ed and \ew do not use Unicode -properties in PCRE. -. -. -.\" HTML -.SS "Simple assertions" -.rs -.sp -The fourth use of backslash is for certain simple assertions. An assertion -specifies a condition that has to be met at a particular point in a match, -without consuming any characters from the subject string. The use of -subpatterns for more complicated assertions is described -.\" HTML -.\" -below. -.\" -The backslashed -assertions are: -.sp - \eb matches at a word boundary - \eB matches when not at a word boundary - \eA matches at start of subject - \eZ matches at end of subject or before newline at end - \ez matches at end of subject - \eG matches at first matching position in subject -.sp -These assertions may not appear in character classes (but note that \eb has a -different meaning, namely the backspace character, inside a character class). -.P -A word boundary is a position in the subject string where the current character -and the previous character do not both match \ew or \eW (i.e. one matches -\ew and the other matches \eW), or the start or end of the string if the -first or last character matches \ew, respectively. -.P -The \eA, \eZ, and \ez assertions differ from the traditional circumflex and -dollar (described in the next section) in that they only ever match at the very -start and end of the subject string, whatever options are set. Thus, they are -independent of multiline mode. These three assertions are not affected by the -PCRE_NOTBOL or PCRE_NOTEOL options, which affect only the behaviour of the -circumflex and dollar metacharacters. However, if the \fIstartoffset\fP -argument of \fBpcre_exec()\fP is non-zero, indicating that matching is to start -at a point other than the beginning of the subject, \eA can never match. The -difference between \eZ and \ez is that \eZ matches before a newline that is the -last character of the string as well as at the end of the string, whereas \ez -matches only at the end. -.P -The \eG assertion is true only when the current matching position is at the -start point of the match, as specified by the \fIstartoffset\fP argument of -\fBpcre_exec()\fP. It differs from \eA when the value of \fIstartoffset\fP is -non-zero. By calling \fBpcre_exec()\fP multiple times with appropriate -arguments, you can mimic Perl's /g option, and it is in this kind of -implementation where \eG can be useful. -.P -Note, however, that PCRE's interpretation of \eG, as the start of the current -match, is subtly different from Perl's, which defines it as the end of the -previous match. In Perl, these can be different when the previously matched -string was empty. Because PCRE does just one match at a time, it cannot -reproduce this behaviour. -.P -If all the alternatives of a pattern begin with \eG, the expression is anchored -to the starting match position, and the "anchored" flag is set in the compiled -regular expression. -. -. -.SH "CIRCUMFLEX AND DOLLAR" -.rs -.sp -Outside a character class, in the default matching mode, the circumflex -character is an assertion that is true only if the current matching point is -at the start of the subject string. If the \fIstartoffset\fP argument of -\fBpcre_exec()\fP is non-zero, circumflex can never match if the PCRE_MULTILINE -option is unset. Inside a character class, circumflex has an entirely different -meaning -.\" HTML -.\" -(see below). -.\" -.P -Circumflex need not be the first character of the pattern if a number of -alternatives are involved, but it should be the first thing in each alternative -in which it appears if the pattern is ever to match that branch. If all -possible alternatives start with a circumflex, that is, if the pattern is -constrained to match only at the start of the subject, it is said to be an -"anchored" pattern. (There are also other constructs that can cause a pattern -to be anchored.) -.P -A dollar character is an assertion that is true only if the current matching -point is at the end of the subject string, or immediately before a newline -character that is the last character in the string (by default). Dollar need -not be the last character of the pattern if a number of alternatives are -involved, but it should be the last item in any branch in which it appears. -Dollar has no special meaning in a character class. -.P -The meaning of dollar can be changed so that it matches only at the very end of -the string, by setting the PCRE_DOLLAR_ENDONLY option at compile time. This -does not affect the \eZ assertion. -.P -The meanings of the circumflex and dollar characters are changed if the -PCRE_MULTILINE option is set. When this is the case, they match immediately -after and immediately before an internal newline character, respectively, in -addition to matching at the start and end of the subject string. For example, -the pattern /^abc$/ matches the subject string "def\enabc" (where \en -represents a newline character) in multiline mode, but not otherwise. -Consequently, patterns that are anchored in single line mode because all -branches start with ^ are not anchored in multiline mode, and a match for -circumflex is possible when the \fIstartoffset\fP argument of \fBpcre_exec()\fP -is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is -set. -.P -Note that the sequences \eA, \eZ, and \ez can be used to match the start and -end of the subject in both modes, and if all branches of a pattern start with -\eA it is always anchored, whether PCRE_MULTILINE is set or not. -. -. -.SH "FULL STOP (PERIOD, DOT)" -.rs -.sp -Outside a character class, a dot in the pattern matches any one character in -the subject, including a non-printing character, but not (by default) newline. -In UTF-8 mode, a dot matches any UTF-8 character, which might be more than one -byte long, except (by default) newline. If the PCRE_DOTALL option is set, -dots match newlines as well. The handling of dot is entirely independent of the -handling of circumflex and dollar, the only relationship being that they both -involve newline characters. Dot has no special meaning in a character class. -. -. -.SH "MATCHING A SINGLE BYTE" -.rs -.sp -Outside a character class, the escape sequence \eC matches any one byte, both -in and out of UTF-8 mode. Unlike a dot, it can match a newline. The feature is -provided in Perl in order to match individual bytes in UTF-8 mode. Because it -breaks up UTF-8 characters into individual bytes, what remains in the string -may be a malformed UTF-8 string. For this reason, the \eC escape sequence is -best avoided. -.P -PCRE does not allow \eC to appear in lookbehind assertions -.\" HTML -.\" -(described below), -.\" -because in UTF-8 mode this would make it impossible to calculate the length of -the lookbehind. -. -. -.\" HTML -.SH "SQUARE BRACKETS AND CHARACTER CLASSES" -.rs -.sp -An opening square bracket introduces a character class, terminated by a closing -square bracket. A closing square bracket on its own is not special. If a -closing square bracket is required as a member of the class, it should be the -first data character in the class (after an initial circumflex, if present) or -escaped with a backslash. -.P -A character class matches a single character in the subject. In UTF-8 mode, the -character may occupy more than one byte. A matched character must be in the set -of characters defined by the class, unless the first character in the class -definition is a circumflex, in which case the subject character must not be in -the set defined by the class. If a circumflex is actually required as a member -of the class, ensure it is not the first character, or escape it with a -backslash. -.P -For example, the character class [aeiou] matches any lower case vowel, while -[^aeiou] matches any character that is not a lower case vowel. Note that a -circumflex is just a convenient notation for specifying the characters that -are in the class by enumerating those that are not. A class that starts with a -circumflex is not an assertion: it still consumes a character from the subject -string, and therefore it fails if the current pointer is at the end of the -string. -.P -In UTF-8 mode, characters with values greater than 255 can be included in a -class as a literal string of bytes, or by using the \ex{ escaping mechanism. -.P -When caseless matching is set, any letters in a class represent both their -upper case and lower case versions, so for example, a caseless [aeiou] matches -"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a -caseful version would. When running in UTF-8 mode, PCRE supports the concept of -case for characters with values greater than 128 only when it is compiled with -Unicode property support. -.P -The newline character is never treated in any special way in character classes, -whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE options is. A class -such as [^a] will always match a newline. -.P -The minus (hyphen) character can be used to specify a range of characters in a -character class. For example, [d-m] matches any letter between d and m, -inclusive. If a minus character is required in a class, it must be escaped with -a backslash or appear in a position where it cannot be interpreted as -indicating a range, typically as the first or last character in the class. -.P -It is not possible to have the literal character "]" as the end character of a -range. A pattern such as [W-]46] is interpreted as a class of two characters -("W" and "-") followed by a literal string "46]", so it would match "W46]" or -"-46]". However, if the "]" is escaped with a backslash it is interpreted as -the end of range, so [W-\e]46] is interpreted as a class containing a range -followed by two other characters. The octal or hexadecimal representation of -"]" can also be used to end a range. -.P -Ranges operate in the collating sequence of character values. They can also be -used for characters specified numerically, for example [\e000-\e037]. In UTF-8 -mode, ranges can include characters whose values are greater than 255, for -example [\ex{100}-\ex{2ff}]. -.P -If a range that includes letters is used when caseless matching is set, it -matches the letters in either case. For example, [W-c] is equivalent to -[][\e\e^_`wxyzabc], matched caselessly, and in non-UTF-8 mode, if character -tables for the "fr_FR" locale are in use, [\exc8-\excb] matches accented E -characters in both cases. In UTF-8 mode, PCRE supports the concept of case for -characters with values greater than 128 only when it is compiled with Unicode -property support. -.P -The character types \ed, \eD, \ep, \eP, \es, \eS, \ew, and \eW may also appear -in a character class, and add the characters that they match to the class. For -example, [\edABCDEF] matches any hexadecimal digit. A circumflex can -conveniently be used with the upper case character types to specify a more -restricted set of characters than the matching lower case type. For example, -the class [^\eW_] matches any letter or digit, but not underscore. -.P -The only metacharacters that are recognized in character classes are backslash, -hyphen (only where it can be interpreted as specifying a range), circumflex -(only at the start), opening square bracket (only when it can be interpreted as -introducing a POSIX class name - see the next section), and the terminating -closing square bracket. However, escaping other non-alphanumeric characters -does no harm. -. -. -.SH "POSIX CHARACTER CLASSES" -.rs -.sp -Perl supports the POSIX notation for character classes. This uses names -enclosed by [: and :] within the enclosing square brackets. PCRE also supports -this notation. For example, -.sp - [01[:alpha:]%] -.sp -matches "0", "1", any alphabetic character, or "%". The supported class names -are -.sp - alnum letters and digits - alpha letters - ascii character codes 0 - 127 - blank space or tab only - cntrl control characters - digit decimal digits (same as \ed) - graph printing characters, excluding space - lower lower case letters - print printing characters, including space - punct printing characters, excluding letters and digits - space white space (not quite the same as \es) - upper upper case letters - word "word" characters (same as \ew) - xdigit hexadecimal digits -.sp -The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), and -space (32). Notice that this list includes the VT character (code 11). This -makes "space" different to \es, which does not include VT (for Perl -compatibility). -.P -The name "word" is a Perl extension, and "blank" is a GNU extension from Perl -5.8. Another Perl extension is negation, which is indicated by a ^ character -after the colon. For example, -.sp - [12[:^digit:]] -.sp -matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the POSIX -syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not -supported, and an error is given if they are encountered. -.P -In UTF-8 mode, characters with values greater than 128 do not match any of -the POSIX character classes. -. -. -.SH "VERTICAL BAR" -.rs -.sp -Vertical bar characters are used to separate alternative patterns. For example, -the pattern -.sp - gilbert|sullivan -.sp -matches either "gilbert" or "sullivan". Any number of alternatives may appear, -and an empty alternative is permitted (matching the empty string). -The matching process tries each alternative in turn, from left to right, -and the first one that succeeds is used. If the alternatives are within a -subpattern -.\" HTML -.\" -(defined below), -.\" -"succeeds" means matching the rest of the main pattern as well as the -alternative in the subpattern. -. -. -.SH "INTERNAL OPTION SETTING" -.rs -.sp -The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and -PCRE_EXTENDED options can be changed from within the pattern by a sequence of -Perl option letters enclosed between "(?" and ")". The option letters are -.sp - i for PCRE_CASELESS - m for PCRE_MULTILINE - s for PCRE_DOTALL - x for PCRE_EXTENDED -.sp -For example, (?im) sets caseless, multiline matching. It is also possible to -unset these options by preceding the letter with a hyphen, and a combined -setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and -PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also -permitted. If a letter appears both before and after the hyphen, the option is -unset. -.P -When an option change occurs at top level (that is, not inside subpattern -parentheses), the change applies to the remainder of the pattern that follows. -If the change is placed right at the start of a pattern, PCRE extracts it into -the global options (and it will therefore show up in data extracted by the -\fBpcre_fullinfo()\fP function). -.P -An option change within a subpattern affects only that part of the current -pattern that follows it, so -.sp - (a(?i)b)c -.sp -matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used). -By this means, options can be made to have different settings in different -parts of the pattern. Any changes made in one alternative do carry on -into subsequent branches within the same subpattern. For example, -.sp - (a(?i)b|c) -.sp -matches "ab", "aB", "c", and "C", even though when matching "C" the first -branch is abandoned before the option setting. This is because the effects of -option settings happen at compile time. There would be some very weird -behaviour otherwise. -.P -The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed in the -same way as the Perl-compatible options by using the characters U and X -respectively. The (?X) flag setting is special in that it must always occur -earlier in the pattern than any of the additional features it turns on, even -when it is at top level. It is best to put it at the start. -. -. -.\" HTML -.SH SUBPATTERNS -.rs -.sp -Subpatterns are delimited by parentheses (round brackets), which can be nested. -Turning part of a pattern into a subpattern does two things: -.sp -1. It localizes a set of alternatives. For example, the pattern -.sp - cat(aract|erpillar|) -.sp -matches one of the words "cat", "cataract", or "caterpillar". Without the -parentheses, it would match "cataract", "erpillar" or the empty string. -.sp -2. It sets up the subpattern as a capturing subpattern. This means that, when -the whole pattern matches, that portion of the subject string that matched the -subpattern is passed back to the caller via the \fIovector\fP argument of -\fBpcre_exec()\fP. Opening parentheses are counted from left to right (starting -from 1) to obtain numbers for the capturing subpatterns. -.P -For example, if the string "the red king" is matched against the pattern -.sp - the ((red|white) (king|queen)) -.sp -the captured substrings are "red king", "red", and "king", and are numbered 1, -2, and 3, respectively. -.P -The fact that plain parentheses fulfil two functions is not always helpful. -There are often times when a grouping subpattern is required without a -capturing requirement. If an opening parenthesis is followed by a question mark -and a colon, the subpattern does not do any capturing, and is not counted when -computing the number of any subsequent capturing subpatterns. For example, if -the string "the white queen" is matched against the pattern -.sp - the ((?:red|white) (king|queen)) -.sp -the captured substrings are "white queen" and "queen", and are numbered 1 and -2. The maximum number of capturing subpatterns is 65535, and the maximum depth -of nesting of all subpatterns, both capturing and non-capturing, is 200. -.P -As a convenient shorthand, if any option settings are required at the start of -a non-capturing subpattern, the option letters may appear between the "?" and -the ":". Thus the two patterns -.sp - (?i:saturday|sunday) - (?:(?i)saturday|sunday) -.sp -match exactly the same set of strings. Because alternative branches are tried -from left to right, and options are not reset until the end of the subpattern -is reached, an option setting in one branch does affect subsequent branches, so -the above patterns match "SUNDAY" as well as "Saturday". -. -. -.SH "NAMED SUBPATTERNS" -.rs -.sp -Identifying capturing parentheses by number is simple, but it can be very hard -to keep track of the numbers in complicated regular expressions. Furthermore, -if an expression is modified, the numbers may change. To help with this -difficulty, PCRE supports the naming of subpatterns, something that Perl does -not provide. The Python syntax (?P...) is used. Names consist of -alphanumeric characters and underscores, and must be unique within a pattern. -.P -Named capturing parentheses are still allocated numbers as well as names. The -PCRE API provides function calls for extracting the name-to-number translation -table from a compiled pattern. There is also a convenience function for -extracting a captured substring by name. For further details see the -.\" HREF -\fBpcreapi\fP -.\" -documentation. -. -. -.SH REPETITION -.rs -.sp -Repetition is specified by quantifiers, which can follow any of the following -items: -.sp - a literal data character - the . metacharacter - the \eC escape sequence - the \eX escape sequence (in UTF-8 mode with Unicode properties) - an escape such as \ed that matches a single character - a character class - a back reference (see next section) - a parenthesized subpattern (unless it is an assertion) -.sp -The general repetition quantifier specifies a minimum and maximum number of -permitted matches, by giving the two numbers in curly brackets (braces), -separated by a comma. The numbers must be less than 65536, and the first must -be less than or equal to the second. For example: -.sp - z{2,4} -.sp -matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special -character. If the second number is omitted, but the comma is present, there is -no upper limit; if the second number and the comma are both omitted, the -quantifier specifies an exact number of required matches. Thus -.sp - [aeiou]{3,} -.sp -matches at least 3 successive vowels, but may match many more, while -.sp - \ed{8} -.sp -matches exactly 8 digits. An opening curly bracket that appears in a position -where a quantifier is not allowed, or one that does not match the syntax of a -quantifier, is taken as a literal character. For example, {,6} is not a -quantifier, but a literal string of four characters. -.P -In UTF-8 mode, quantifiers apply to UTF-8 characters rather than to individual -bytes. Thus, for example, \ex{100}{2} matches two UTF-8 characters, each of -which is represented by a two-byte sequence. Similarly, when Unicode property -support is available, \eX{3} matches three Unicode extended sequences, each of -which may be several bytes long (and they may be of different lengths). -.P -The quantifier {0} is permitted, causing the expression to behave as if the -previous item and the quantifier were not present. -.P -For convenience (and historical compatibility) the three most common -quantifiers have single-character abbreviations: -.sp - * is equivalent to {0,} - + is equivalent to {1,} - ? is equivalent to {0,1} -.sp -It is possible to construct infinite loops by following a subpattern that can -match no characters with a quantifier that has no upper limit, for example: -.sp - (a?)* -.sp -Earlier versions of Perl and PCRE used to give an error at compile time for -such patterns. However, because there are cases where this can be useful, such -patterns are now accepted, but if any repetition of the subpattern does in fact -match no characters, the loop is forcibly broken. -.P -By default, the quantifiers are "greedy", that is, they match as much as -possible (up to the maximum number of permitted times), without causing the -rest of the pattern to fail. The classic example of where this gives problems -is in trying to match comments in C programs. These appear between /* and */ -and within the comment, individual * and / characters may appear. An attempt to -match C comments by applying the pattern -.sp - /\e*.*\e*/ -.sp -to the string -.sp - /* first comment */ not comment /* second comment */ -.sp -fails, because it matches the entire string owing to the greediness of the .* -item. -.P -However, if a quantifier is followed by a question mark, it ceases to be -greedy, and instead matches the minimum number of times possible, so the -pattern -.sp - /\e*.*?\e*/ -.sp -does the right thing with the C comments. The meaning of the various -quantifiers is not otherwise changed, just the preferred number of matches. -Do not confuse this use of question mark with its use as a quantifier in its -own right. Because it has two uses, it can sometimes appear doubled, as in -.sp - \ed??\ed -.sp -which matches one digit by preference, but can match two if that is the only -way the rest of the pattern matches. -.P -If the PCRE_UNGREEDY option is set (an option which is not available in Perl), -the quantifiers are not greedy by default, but individual ones can be made -greedy by following them with a question mark. In other words, it inverts the -default behaviour. -.P -When a parenthesized subpattern is quantified with a minimum repeat count that -is greater than 1 or with a limited maximum, more memory is required for the -compiled pattern, in proportion to the size of the minimum or maximum. -.P -If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent -to Perl's /s) is set, thus allowing the . to match newlines, the pattern is -implicitly anchored, because whatever follows will be tried against every -character position in the subject string, so there is no point in retrying the -overall match at any position after the first. PCRE normally treats such a -pattern as though it were preceded by \eA. -.P -In cases where it is known that the subject string contains no newlines, it is -worth setting PCRE_DOTALL in order to obtain this optimization, or -alternatively using ^ to indicate anchoring explicitly. -.P -However, there is one situation where the optimization cannot be used. When .* -is inside capturing parentheses that are the subject of a backreference -elsewhere in the pattern, a match at the start may fail, and a later one -succeed. Consider, for example: -.sp - (.*)abc\e1 -.sp -If the subject is "xyz123abc123" the match point is the fourth character. For -this reason, such a pattern is not implicitly anchored. -.P -When a capturing subpattern is repeated, the value captured is the substring -that matched the final iteration. For example, after -.sp - (tweedle[dume]{3}\es*)+ -.sp -has matched "tweedledum tweedledee" the value of the captured substring is -"tweedledee". However, if there are nested capturing subpatterns, the -corresponding captured values may have been set in previous iterations. For -example, after -.sp - /(a|(b))+/ -.sp -matches "aba" the value of the second captured substring is "b". -. -. -.\" HTML -.SH "ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS" -.rs -.sp -With both maximizing and minimizing repetition, failure of what follows -normally causes the repeated item to be re-evaluated to see if a different -number of repeats allows the rest of the pattern to match. Sometimes it is -useful to prevent this, either to change the nature of the match, or to cause -it fail earlier than it otherwise might, when the author of the pattern knows -there is no point in carrying on. -.P -Consider, for example, the pattern \ed+foo when applied to the subject line -.sp - 123456bar -.sp -After matching all 6 digits and then failing to match "foo", the normal -action of the matcher is to try again with only 5 digits matching the \ed+ -item, and then with 4, and so on, before ultimately failing. "Atomic grouping" -(a term taken from Jeffrey Friedl's book) provides the means for specifying -that once a subpattern has matched, it is not to be re-evaluated in this way. -.P -If we use atomic grouping for the previous example, the matcher would give up -immediately on failing to match "foo" the first time. The notation is a kind of -special parenthesis, starting with (?> as in this example: -.sp - (?>\ed+)foo -.sp -This kind of parenthesis "locks up" the part of the pattern it contains once -it has matched, and a failure further into the pattern is prevented from -backtracking into it. Backtracking past it to previous items, however, works as -normal. -.P -An alternative description is that a subpattern of this type matches the string -of characters that an identical standalone pattern would match, if anchored at -the current point in the subject string. -.P -Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as -the above example can be thought of as a maximizing repeat that must swallow -everything it can. So, while both \ed+ and \ed+? are prepared to adjust the -number of digits they match in order to make the rest of the pattern match, -(?>\ed+) can only match an entire sequence of digits. -.P -Atomic groups in general can of course contain arbitrarily complicated -subpatterns, and can be nested. However, when the subpattern for an atomic -group is just a single repeated item, as in the example above, a simpler -notation, called a "possessive quantifier" can be used. This consists of an -additional + character following a quantifier. Using this notation, the -previous example can be rewritten as -.sp - \ed++foo -.sp -Possessive quantifiers are always greedy; the setting of the PCRE_UNGREEDY -option is ignored. They are a convenient notation for the simpler forms of -atomic group. However, there is no difference in the meaning or processing of a -possessive quantifier and the equivalent atomic group. -.P -The possessive quantifier syntax is an extension to the Perl syntax. It -originates in Sun's Java package. -.P -When a pattern contains an unlimited repeat inside a subpattern that can itself -be repeated an unlimited number of times, the use of an atomic group is the -only way to avoid some failing matches taking a very long time indeed. The -pattern -.sp - (\eD+|<\ed+>)*[!?] -.sp -matches an unlimited number of substrings that either consist of non-digits, or -digits enclosed in <>, followed by either ! or ?. When it matches, it runs -quickly. However, if it is applied to -.sp - aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa -.sp -it takes a long time before reporting failure. This is because the string can -be divided between the internal \eD+ repeat and the external * repeat in a -large number of ways, and all have to be tried. (The example uses [!?] rather -than a single character at the end, because both PCRE and Perl have an -optimization that allows for fast failure when a single character is used. They -remember the last single character that is required for a match, and fail early -if it is not present in the string.) If the pattern is changed so that it uses -an atomic group, like this: -.sp - ((?>\eD+)|<\ed+>)*[!?] -.sp -sequences of non-digits cannot be broken, and failure happens quickly. -. -. -.\" HTML -.SH "BACK REFERENCES" -.rs -.sp -Outside a character class, a backslash followed by a digit greater than 0 (and -possibly further digits) is a back reference to a capturing subpattern earlier -(that is, to its left) in the pattern, provided there have been that many -previous capturing left parentheses. -.P -However, if the decimal number following the backslash is less than 10, it is -always taken as a back reference, and causes an error only if there are not -that many capturing left parentheses in the entire pattern. In other words, the -parentheses that are referenced need not be to the left of the reference for -numbers less than 10. See the subsection entitled "Non-printing characters" -.\" HTML -.\" -above -.\" -for further details of the handling of digits following a backslash. -.P -A back reference matches whatever actually matched the capturing subpattern in -the current subject string, rather than anything matching the subpattern -itself (see -.\" HTML -.\" -"Subpatterns as subroutines" -.\" -below for a way of doing that). So the pattern -.sp - (sens|respons)e and \e1ibility -.sp -matches "sense and sensibility" and "response and responsibility", but not -"sense and responsibility". If caseful matching is in force at the time of the -back reference, the case of letters is relevant. For example, -.sp - ((?i)rah)\es+\e1 -.sp -matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original -capturing subpattern is matched caselessly. -.P -Back references to named subpatterns use the Python syntax (?P=name). We could -rewrite the above example as follows: -.sp - (?(?i)rah)\es+(?P=p1) -.sp -There may be more than one back reference to the same subpattern. If a -subpattern has not actually been used in a particular match, any back -references to it always fail. For example, the pattern -.sp - (a|(bc))\e2 -.sp -always fails if it starts to match "a" rather than "bc". Because there may be -many capturing parentheses in a pattern, all digits following the backslash are -taken as part of a potential back reference number. If the pattern continues -with a digit character, some delimiter must be used to terminate the back -reference. If the PCRE_EXTENDED option is set, this can be whitespace. -Otherwise an empty comment (see -.\" HTML -.\" -"Comments" -.\" -below) can be used. -.P -A back reference that occurs inside the parentheses to which it refers fails -when the subpattern is first used, so, for example, (a\e1) never matches. -However, such references can be useful inside repeated subpatterns. For -example, the pattern -.sp - (a|b\e1)+ -.sp -matches any number of "a"s and also "aba", "ababbaa" etc. At each iteration of -the subpattern, the back reference matches the character string corresponding -to the previous iteration. In order for this to work, the pattern must be such -that the first iteration does not need to match the back reference. This can be -done using alternation, as in the example above, or by a quantifier with a -minimum of zero. -. -. -.\" HTML -.SH ASSERTIONS -.rs -.sp -An assertion is a test on the characters following or preceding the current -matching point that does not actually consume any characters. The simple -assertions coded as \eb, \eB, \eA, \eG, \eZ, \ez, ^ and $ are described -.\" HTML -.\" -above. -.\" -.P -More complicated assertions are coded as subpatterns. There are two kinds: -those that look ahead of the current position in the subject string, and those -that look behind it. An assertion subpattern is matched in the normal way, -except that it does not cause the current matching position to be changed. -.P -Assertion subpatterns are not capturing subpatterns, and may not be repeated, -because it makes no sense to assert the same thing several times. If any kind -of assertion contains capturing subpatterns within it, these are counted for -the purposes of numbering the capturing subpatterns in the whole pattern. -However, substring capturing is carried out only for positive assertions, -because it does not make sense for negative assertions. -. -. -.SS "Lookahead assertions" -.rs -.sp -Lookahead assertions start -with (?= for positive assertions and (?! for negative assertions. For example, -.sp - \ew+(?=;) -.sp -matches a word followed by a semicolon, but does not include the semicolon in -the match, and -.sp - foo(?!bar) -.sp -matches any occurrence of "foo" that is not followed by "bar". Note that the -apparently similar pattern -.sp - (?!foo)bar -.sp -does not find an occurrence of "bar" that is preceded by something other than -"foo"; it finds any occurrence of "bar" whatsoever, because the assertion -(?!foo) is always true when the next three characters are "bar". A -lookbehind assertion is needed to achieve the other effect. -.P -If you want to force a matching failure at some point in a pattern, the most -convenient way to do it is with (?!) because an empty string always matches, so -an assertion that requires there not to be an empty string must always fail. -. -. -.\" HTML -.SS "Lookbehind assertions" -.rs -.sp -Lookbehind assertions start with (?<= for positive assertions and (?.*)(?<=abcd) -.sp -or, equivalently, using the possessive quantifier syntax, -.sp - ^.*+(?<=abcd) -.sp -there can be no backtracking for the .* item; it can match only the entire -string. The subsequent lookbehind assertion does a single test on the last four -characters. If it fails, the match fails immediately. For long strings, this -approach makes a significant difference to the processing time. -. -. -.SS "Using multiple assertions" -.rs -.sp -Several assertions (of any sort) may occur in succession. For example, -.sp - (?<=\ed{3})(? -.SH COMMENTS -.rs -.sp -The sequence (?# marks the start of a comment that continues up to the next -closing parenthesis. Nested parentheses are not permitted. The characters -that make up a comment play no part in the pattern matching at all. -.P -If the PCRE_EXTENDED option is set, an unescaped # character outside a -character class introduces a comment that continues up to the next newline -character in the pattern. -. -. -.SH "RECURSIVE PATTERNS" -.rs -.sp -Consider the problem of matching a string in parentheses, allowing for -unlimited nested parentheses. Without the use of recursion, the best that can -be done is to use a pattern that matches up to some fixed depth of nesting. It -is not possible to handle an arbitrary nesting depth. Perl provides a facility -that allows regular expressions to recurse (amongst other things). It does this -by interpolating Perl code in the expression at run time, and the code can -refer to the expression itself. A Perl pattern to solve the parentheses problem -can be created like this: -.sp - $re = qr{\e( (?: (?>[^()]+) | (?p{$re}) )* \e)}x; -.sp -The (?p{...}) item interpolates Perl code at run time, and in this case refers -recursively to the pattern in which it appears. Obviously, PCRE cannot support -the interpolation of Perl code. Instead, it supports some special syntax for -recursion of the entire pattern, and also for individual subpattern recursion. -.P -The special item that consists of (? followed by a number greater than zero and -a closing parenthesis is a recursive call of the subpattern of the given -number, provided that it occurs inside that subpattern. (If not, it is a -"subroutine" call, which is described in the next section.) The special item -(?R) is a recursive call of the entire regular expression. -.P -For example, this PCRE pattern solves the nested parentheses problem (assume -the PCRE_EXTENDED option is set so that white space is ignored): -.sp - \e( ( (?>[^()]+) | (?R) )* \e) -.sp -First it matches an opening parenthesis. Then it matches any number of -substrings which can either be a sequence of non-parentheses, or a recursive -match of the pattern itself (that is a correctly parenthesized substring). -Finally there is a closing parenthesis. -.P -If this were part of a larger pattern, you would not want to recurse the entire -pattern, so instead you could use this: -.sp - ( \e( ( (?>[^()]+) | (?1) )* \e) ) -.sp -We have put the pattern into parentheses, and caused the recursion to refer to -them instead of the whole pattern. In a larger pattern, keeping track of -parenthesis numbers can be tricky. It may be more convenient to use named -parentheses instead. For this, PCRE uses (?P>name), which is an extension to -the Python syntax that PCRE uses for named parentheses (Perl does not provide -named parentheses). We could rewrite the above example as follows: -.sp - (?P \e( ( (?>[^()]+) | (?P>pn) )* \e) ) -.sp -This particular example pattern contains nested unlimited repeats, and so the -use of atomic grouping for matching strings of non-parentheses is important -when applying the pattern to strings that do not match. For example, when this -pattern is applied to -.sp - (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa() -.sp -it yields "no match" quickly. However, if atomic grouping is not used, -the match runs for a very long time indeed because there are so many different -ways the + and * repeats can carve up the subject, and all have to be tested -before failure can be reported. -.P -At the end of a match, the values set for any capturing subpatterns are those -from the outermost level of the recursion at which the subpattern value is set. -If you want to obtain intermediate values, a callout function can be used (see -the next section and the -.\" HREF -\fBpcrecallout\fP -.\" -documentation). If the pattern above is matched against -.sp - (ab(cd)ef) -.sp -the value for the capturing parentheses is "ef", which is the last value taken -on at the top level. If additional parentheses are added, giving -.sp - \e( ( ( (?>[^()]+) | (?R) )* ) \e) - ^ ^ - ^ ^ -.sp -the string they capture is "ab(cd)ef", the contents of the top level -parentheses. If there are more than 15 capturing parentheses in a pattern, PCRE -has to obtain extra memory to store data during a recursion, which it does by -using \fBpcre_malloc\fP, freeing it via \fBpcre_free\fP afterwards. If no -memory can be obtained, the match fails with the PCRE_ERROR_NOMEMORY error. -.P -Do not confuse the (?R) item with the condition (R), which tests for recursion. -Consider this pattern, which matches text in angle brackets, allowing for -arbitrary nesting. Only digits are allowed in nested brackets (that is, when -recursing), whereas any characters are permitted at the outer level. -.sp - < (?: (?(R) \ed++ | [^<>]*+) | (?R)) * > -.sp -In this pattern, (?(R) is the start of a conditional subpattern, with two -different alternatives for the recursive and non-recursive cases. The (?R) item -is the actual recursive call. -. -. -.\" HTML -.SH "SUBPATTERNS AS SUBROUTINES" -.rs -.sp -If the syntax for a recursive subpattern reference (either by number or by -name) is used outside the parentheses to which it refers, it operates like a -subroutine in a programming language. An earlier example pointed out that the -pattern -.sp - (sens|respons)e and \e1ibility -.sp -matches "sense and sensibility" and "response and responsibility", but not -"sense and responsibility". If instead the pattern -.sp - (sens|respons)e and (?1)ibility -.sp -is used, it does match "sense and responsibility" as well as the other two -strings. Such references must, however, follow the subpattern to which they -refer. -. -. -.SH CALLOUTS -.rs -.sp -Perl has a feature whereby using the sequence (?{...}) causes arbitrary Perl -code to be obeyed in the middle of matching a regular expression. This makes it -possible, amongst other things, to extract different substrings that match the -same pair of parentheses when there is a repetition. -.P -PCRE provides a similar feature, but of course it cannot obey arbitrary Perl -code. The feature is called "callout". The caller of PCRE provides an external -function by putting its entry point in the global variable \fIpcre_callout\fP. -By default, this variable contains NULL, which disables all calling out. -.P -Within a regular expression, (?C) indicates the points at which the external -function is to be called. If you want to identify different callout points, you -can put a number less than 256 after the letter C. The default value is zero. -For example, this pattern has two callout points: -.sp - (?C1)\dabc(?C2)def -.sp -If the PCRE_AUTO_CALLOUT flag is passed to \fBpcre_compile()\fP, callouts are -automatically installed before each item in the pattern. They are all numbered -255. -.P -During matching, when PCRE reaches a callout point (and \fIpcre_callout\fP is -set), the external function is called. It is provided with the number of the -callout, the position in the pattern, and, optionally, one item of data -originally supplied by the caller of \fBpcre_exec()\fP. The callout function -may cause matching to proceed, to backtrack, or to fail altogether. A complete -description of the interface to the callout function is given in the -.\" HREF -\fBpcrecallout\fP -.\" -documentation. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcreperform.3 b/srclib/pcre/doc/pcreperform.3 deleted file mode 100644 index 999268eaf6..0000000000 --- a/srclib/pcre/doc/pcreperform.3 +++ /dev/null @@ -1,76 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PCRE PERFORMANCE" -.rs -.sp -Certain items that may appear in regular expression patterns are more efficient -than others. It is more efficient to use a character class like [aeiou] than a -set of alternatives such as (a|e|i|o|u). In general, the simplest construction -that provides the required behaviour is usually the most efficient. Jeffrey -Friedl's book contains a lot of useful general discussion about optimizing -regular expressions for efficient performance. This document contains a few -observations about PCRE. -.P -Using Unicode character properties (the \ep, \eP, and \eX escapes) is slow, -because PCRE has to scan a structure that contains data for over fifteen -thousand characters whenever it needs a character's property. If you can find -an alternative pattern that does not use character properties, it will probably -be faster. -.P -When a pattern begins with .* not in parentheses, or in parentheses that are -not the subject of a backreference, and the PCRE_DOTALL option is set, the -pattern is implicitly anchored by PCRE, since it can match only at the start of -a subject string. However, if PCRE_DOTALL is not set, PCRE cannot make this -optimization, because the . metacharacter does not then match a newline, and if -the subject string contains newlines, the pattern may match from the character -immediately following one of them instead of from the very start. For example, -the pattern -.sp - .*second -.sp -matches the subject "first\enand second" (where \en stands for a newline -character), with the match starting at the seventh character. In order to do -this, PCRE has to retry the match starting after every newline in the subject. -.P -If you are using such a pattern with subject strings that do not contain -newlines, the best performance is obtained by setting PCRE_DOTALL, or starting -the pattern with ^.* to indicate explicit anchoring. That saves PCRE from -having to scan along the subject looking for a newline to restart at. -.P -Beware of patterns that contain nested indefinite repeats. These can take a -long time to run when applied to a string that does not match. Consider the -pattern fragment -.sp - (a+)* -.sp -This can match "aaaa" in 33 different ways, and this number increases very -rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4 -times, and for each of those cases other than 0, the + repeats can match -different numbers of times.) When the remainder of the pattern is such that the -entire match is going to fail, PCRE has in principle to try every possible -variation, and this can take an extremely long time. -.P -An optimization catches some of the more simple cases such as -.sp - (a+)*b -.sp -where a literal character follows. Before embarking on the standard matching -procedure, PCRE checks that there is a "b" later in the subject string, and if -there is not, it fails the match immediately. However, when there is no -following literal this optimization cannot be used. You can see the difference -by comparing the behaviour of -.sp - (a+)*\ed -.sp -with the pattern above. The former gives a failure almost instantly when -applied to a whole line of "a" characters, whereas the latter takes an -appreciable time with strings longer than about 20 characters. -.P -In many cases, the solution to this kind of performance issue is to use an -atomic group or a possessive quantifier. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcreposix.3 b/srclib/pcre/doc/pcreposix.3 deleted file mode 100644 index 321dcd7ac9..0000000000 --- a/srclib/pcre/doc/pcreposix.3 +++ /dev/null @@ -1,201 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions. -.SH "SYNOPSIS OF POSIX API" -.rs -.sp -.B #include -.PP -.SM -.br -.B int regcomp(regex_t *\fIpreg\fP, const char *\fIpattern\fP, -.ti +5n -.B int \fIcflags\fP); -.PP -.br -.B int regexec(regex_t *\fIpreg\fP, const char *\fIstring\fP, -.ti +5n -.B size_t \fInmatch\fP, regmatch_t \fIpmatch\fP[], int \fIeflags\fP); -.PP -.br -.B size_t regerror(int \fIerrcode\fP, const regex_t *\fIpreg\fP, -.ti +5n -.B char *\fIerrbuf\fP, size_t \fIerrbuf_size\fP); -.PP -.br -.B void regfree(regex_t *\fIpreg\fP); -. -.SH DESCRIPTION -.rs -.sp -This set of functions provides a POSIX-style API to the PCRE regular expression -package. See the -.\" HREF -\fBpcreapi\fP -.\" -documentation for a description of PCRE's native API, which contains additional -functionality. -.P -The functions described here are just wrapper functions that ultimately call -the PCRE native API. Their prototypes are defined in the \fBpcreposix.h\fP -header file, and on Unix systems the library itself is called -\fBpcreposix.a\fP, so can be accessed by adding \fB-lpcreposix\fP to the -command for linking an application that uses them. Because the POSIX functions -call the native ones, it is also necessary to add \fB-lpcre\fP. -.P -I have implemented only those option bits that can be reasonably mapped to PCRE -native options. In addition, the options REG_EXTENDED and REG_NOSUB are defined -with the value zero. They have no effect, but since programs that are written -to the POSIX interface often use them, this makes it easier to slot in PCRE as -a replacement library. Other POSIX options are not even defined. -.P -When PCRE is called via these functions, it is only the API that is POSIX-like -in style. The syntax and semantics of the regular expressions themselves are -still those of Perl, subject to the setting of various PCRE options, as -described below. "POSIX-like in style" means that the API approximates to the -POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding -domains it is probably even less compatible. -.P -The header for these functions is supplied as \fBpcreposix.h\fP to avoid any -potential clash with other POSIX libraries. It can, of course, be renamed or -aliased as \fBregex.h\fP, which is the "correct" name. It provides two -structure types, \fIregex_t\fP for compiled internal forms, and -\fIregmatch_t\fP for returning captured substrings. It also defines some -constants whose names start with "REG_"; these are used for setting options and -identifying error codes. -.P -.SH "COMPILING A PATTERN" -.rs -.sp -The function \fBregcomp()\fP is called to compile a pattern into an -internal form. The pattern is a C string terminated by a binary zero, and -is passed in the argument \fIpattern\fP. The \fIpreg\fP argument is a pointer -to a \fBregex_t\fP structure that is used as a base for storing information -about the compiled expression. -.P -The argument \fIcflags\fP is either zero, or contains one or more of the bits -defined by the following macros: -.sp - REG_ICASE -.sp -The PCRE_CASELESS option is set when the expression is passed for compilation -to the native function. -.sp - REG_NEWLINE -.sp -The PCRE_MULTILINE option is set when the expression is passed for compilation -to the native function. Note that this does \fInot\fP mimic the defined POSIX -behaviour for REG_NEWLINE (see the following section). -.P -In the absence of these flags, no options are passed to the native function. -This means the the regex is compiled with PCRE default semantics. In -particular, the way it handles newline characters in the subject string is the -Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only -\fIsome\fP of the effects specified for REG_NEWLINE. It does not affect the way -newlines are matched by . (they aren't) or by a negative class such as [^a] -(they are). -.P -The yield of \fBregcomp()\fP is zero on success, and non-zero otherwise. The -\fIpreg\fP structure is filled in on success, and one member of the structure -is public: \fIre_nsub\fP contains the number of capturing subpatterns in -the regular expression. Various error codes are defined in the header file. -. -. -.SH "MATCHING NEWLINE CHARACTERS" -.rs -.sp -This area is not simple, because POSIX and Perl take different views of things. -It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never -intended to be a POSIX engine. The following table lists the different -possibilities for matching newline characters in PCRE: -.sp - Default Change with -.sp - . matches newline no PCRE_DOTALL - newline matches [^a] yes not changeable - $ matches \en at end yes PCRE_DOLLARENDONLY - $ matches \en in middle no PCRE_MULTILINE - ^ matches \en in middle no PCRE_MULTILINE -.sp -This is the equivalent table for POSIX: -.sp - Default Change with -.sp - . matches newline yes REG_NEWLINE - newline matches [^a] yes REG_NEWLINE - $ matches \en at end no REG_NEWLINE - $ matches \en in middle no REG_NEWLINE - ^ matches \en in middle no REG_NEWLINE -.sp -PCRE's behaviour is the same as Perl's, except that there is no equivalent for -PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop -newline from matching [^a]. -.P -The default POSIX newline handling can be obtained by setting PCRE_DOTALL and -PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the -REG_NEWLINE action. -. -. -.SH "MATCHING A PATTERN" -.rs -.sp -The function \fBregexec()\fP is called to match a compiled pattern \fIpreg\fP -against a given \fIstring\fP, which is terminated by a zero byte, subject to -the options in \fIeflags\fP. These can be: -.sp - REG_NOTBOL -.sp -The PCRE_NOTBOL option is set when calling the underlying PCRE matching -function. -.sp - REG_NOTEOL -.sp -The PCRE_NOTEOL option is set when calling the underlying PCRE matching -function. -.P -The portion of the string that was matched, and also any captured substrings, -are returned via the \fIpmatch\fP argument, which points to an array of -\fInmatch\fP structures of type \fIregmatch_t\fP, containing the members -\fIrm_so\fP and \fIrm_eo\fP. These contain the offset to the first character of -each substring and the offset to the first character after the end of each -substring, respectively. The 0th element of the vector relates to the entire -portion of \fIstring\fP that was matched; subsequent elements relate to the -capturing subpatterns of the regular expression. Unused entries in the array -have both structure members set to -1. -.P -A successful match yields a zero return; various error codes are defined in the -header file, of which REG_NOMATCH is the "expected" failure code. -. -. -.SH "ERROR MESSAGES" -.rs -.sp -The \fBregerror()\fP function maps a non-zero errorcode from either -\fBregcomp()\fP or \fBregexec()\fP to a printable message. If \fIpreg\fP is not -NULL, the error should have arisen from the use of that structure. A message -terminated by a binary zero is placed in \fIerrbuf\fP. The length of the -message, including the zero, is limited to \fIerrbuf_size\fP. The yield of the -function is the size of buffer needed to hold the whole message. -. -. -.SH MEMORY USAGE -.rs -.sp -Compiling a regular expression causes memory to be allocated and associated -with the \fIpreg\fP structure. The function \fBregfree()\fP frees all such -memory, after which \fIpreg\fP may no longer be used as a compiled expression. -. -. -.SH AUTHOR -.rs -.sp -Philip Hazel -.br -University Computing Service, -.br -Cambridge CB2 3QG, England. -.P -.in 0 -Last updated: 07 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcreposix.html b/srclib/pcre/doc/pcreposix.html deleted file mode 100644 index 9c89478420..0000000000 --- a/srclib/pcre/doc/pcreposix.html +++ /dev/null @@ -1,191 +0,0 @@ - - -pcreposix specification - - -

    pcreposix specification

    -This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page in case the -conversion went wrong. - -
  • NAME -

    -pcreposix - POSIX API for Perl-compatible regular expressions. -

    -
  • SYNOPSIS -

    -#include <pcreposix.h> -

    -

    -int regcomp(regex_t *preg, const char *pattern, -int cflags); -

    -

    -int regexec(regex_t *preg, const char *string, -size_t nmatch, regmatch_t pmatch[], int eflags); -

    -

    -size_t regerror(int errcode, const regex_t *preg, -char *errbuf, size_t errbuf_size); -

    -

    -void regfree(regex_t *preg); -

    -
  • DESCRIPTION -

    -This set of functions provides a POSIX-style API to the PCRE regular expression -package. See the pcre documentation for a description of the native API, -which contains additional functionality. -

    -

    -The functions described here are just wrapper functions that ultimately call -the native API. Their prototypes are defined in the pcreposix.h header -file, and on Unix systems the library itself is called pcreposix.a, so -can be accessed by adding -lpcreposix to the command for linking an -application which uses them. Because the POSIX functions call the native ones, -it is also necessary to add \fR-lpcre\fR. -

    -

    -I have implemented only those option bits that can be reasonably mapped to PCRE -native options. In addition, the options REG_EXTENDED and REG_NOSUB are defined -with the value zero. They have no effect, but since programs that are written -to the POSIX interface often use them, this makes it easier to slot in PCRE as -a replacement library. Other POSIX options are not even defined. -

    -

    -When PCRE is called via these functions, it is only the API that is POSIX-like -in style. The syntax and semantics of the regular expressions themselves are -still those of Perl, subject to the setting of various PCRE options, as -described below. -

    -

    -The header for these functions is supplied as pcreposix.h to avoid any -potential clash with other POSIX libraries. It can, of course, be renamed or -aliased as regex.h, which is the "correct" name. It provides two -structure types, regex_t for compiled internal forms, and -regmatch_t for returning captured substrings. It also defines some -constants whose names start with "REG_"; these are used for setting options and -identifying error codes. -

    -
  • COMPILING A PATTERN -

    -The function regcomp() is called to compile a pattern into an -internal form. The pattern is a C string terminated by a binary zero, and -is passed in the argument pattern. The preg argument is a pointer -to a regex_t structure which is used as a base for storing information about -the compiled expression. -

    -

    -The argument cflags is either zero, or contains one or more of the bits -defined by the following macros: -

    -

    -

    -  REG_ICASE
-
    -

    -

    -The PCRE_CASELESS option is set when the expression is passed for compilation -to the native function. -

    -

    -

    -  REG_NEWLINE
-
    -

    -

    -The PCRE_MULTILINE option is set when the expression is passed for compilation -to the native function. -

    -

    -In the absence of these flags, no options are passed to the native function. -This means the the regex is compiled with PCRE default semantics. In -particular, the way it handles newline characters in the subject string is the -Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only -some of the effects specified for REG_NEWLINE. It does not affect the way -newlines are matched by . (they aren't) or a negative class such as [^a] (they -are). -

    -

    -The yield of regcomp() is zero on success, and non-zero otherwise. The -preg structure is filled in on success, and one member of the structure -is publicized: re_nsub contains the number of capturing subpatterns in -the regular expression. Various error codes are defined in the header file. -

    -
  • MATCHING A PATTERN -

    -The function regexec() is called to match a pre-compiled pattern -preg against a given string, which is terminated by a zero byte, -subject to the options in eflags. These can be: -

    -

    -

    -  REG_NOTBOL
-
    -

    -

    -The PCRE_NOTBOL option is set when calling the underlying PCRE matching -function. -

    -

    -

    -  REG_NOTEOL
-
    -

    -

    -The PCRE_NOTEOL option is set when calling the underlying PCRE matching -function. -

    -

    -The portion of the string that was matched, and also any captured substrings, -are returned via the pmatch argument, which points to an array of -nmatch structures of type regmatch_t, containing the members -rm_so and rm_eo. These contain the offset to the first character of -each substring and the offset to the first character after the end of each -substring, respectively. The 0th element of the vector relates to the entire -portion of string that was matched; subsequent elements relate to the -capturing subpatterns of the regular expression. Unused entries in the array -have both structure members set to -1. -

    -

    -A successful match yields a zero return; various error codes are defined in the -header file, of which REG_NOMATCH is the "expected" failure code. -

    -
  • ERROR MESSAGES -

    -The regerror() function maps a non-zero errorcode from either -regcomp or regexec to a printable message. If preg is not -NULL, the error should have arisen from the use of that structure. A message -terminated by a binary zero is placed in errbuf. The length of the -message, including the zero, is limited to errbuf_size. The yield of the -function is the size of buffer needed to hold the whole message. -

    -
  • STORAGE -

    -Compiling a regular expression causes memory to be allocated and associated -with the preg structure. The function regfree() frees all such -memory, after which preg may no longer be used as a compiled expression. -

    -
  • AUTHOR -

    -Philip Hazel <ph10@cam.ac.uk> -
    -University Computing Service, -
    -New Museums Site, -
    -Cambridge CB2 3QG, England. -
    -Phone: +44 1223 334714 -

    -

    -Copyright (c) 1997-2000 University of Cambridge. diff --git a/srclib/pcre/doc/pcreposix.txt b/srclib/pcre/doc/pcreposix.txt deleted file mode 100644 index 2d76f7cdcc..0000000000 --- a/srclib/pcre/doc/pcreposix.txt +++ /dev/null @@ -1,159 +0,0 @@ -NAME - pcreposix - POSIX API for Perl-compatible regular expres- - sions. - - - -SYNOPSIS - #include - - int regcomp(regex_t *preg, const char *pattern, - int cflags); - - int regexec(regex_t *preg, const char *string, - size_t nmatch, regmatch_t pmatch[], int eflags); - - size_t regerror(int errcode, const regex_t *preg, - char *errbuf, size_t errbuf_size); - - void regfree(regex_t *preg); - - - -DESCRIPTION - This set of functions provides a POSIX-style API to the PCRE - regular expression package. See the pcre documentation for a - description of the native API, which contains additional - functionality. - - The functions described here are just wrapper functions that - ultimately call the native API. Their prototypes are defined - in the pcreposix.h header file, and on Unix systems the - library itself is called pcreposix.a, so can be accessed by - adding -lpcreposix to the command for linking an application - which uses them. Because the POSIX functions call the native - ones, it is also necessary to add -lpcre. - - I have implemented only those option bits that can be rea- - sonably mapped to PCRE native options. In addition, the - options REG_EXTENDED and REG_NOSUB are defined with the - value zero. They have no effect, but since programs that are - written to the POSIX interface often use them, this makes it - easier to slot in PCRE as a replacement library. Other POSIX - options are not even defined. - - When PCRE is called via these functions, it is only the API - that is POSIX-like in style. The syntax and semantics of the - regular expressions themselves are still those of Perl, sub- - ject to the setting of various PCRE options, as described - below. - - The header for these functions is supplied as pcreposix.h to - avoid any potential clash with other POSIX libraries. It - can, of course, be renamed or aliased as regex.h, which is - the "correct" name. It provides two structure types, regex_t - for compiled internal forms, and regmatch_t for returning - captured substrings. It also defines some constants whose - names start with "REG_"; these are used for setting options - and identifying error codes. - - - -COMPILING A PATTERN - The function regcomp() is called to compile a pattern into - an internal form. The pattern is a C string terminated by a - binary zero, and is passed in the argument pattern. The preg - argument is a pointer to a regex_t structure which is used - as a base for storing information about the compiled expres- - sion. - - The argument cflags is either zero, or contains one or more - of the bits defined by the following macros: - - REG_ICASE - - The PCRE_CASELESS option is set when the expression is - passed for compilation to the native function. - - REG_NEWLINE - - The PCRE_MULTILINE option is set when the expression is - passed for compilation to the native function. - - In the absence of these flags, no options are passed to the - native function. This means the the regex is compiled with - PCRE default semantics. In particular, the way it handles - newline characters in the subject string is the Perl way, - not the POSIX way. Note that setting PCRE_MULTILINE has only - some of the effects specified for REG_NEWLINE. It does not - affect the way newlines are matched by . (they aren't) or a - negative class such as [^a] (they are). - - The yield of regcomp() is zero on success, and non-zero oth- - erwise. The preg structure is filled in on success, and one - member of the structure is publicized: re_nsub contains the - number of capturing subpatterns in the regular expression. - Various error codes are defined in the header file. - - - -MATCHING A PATTERN - The function regexec() is called to match a pre-compiled - pattern preg against a given string, which is terminated by - a zero byte, subject to the options in eflags. These can be: - - REG_NOTBOL - - The PCRE_NOTBOL option is set when calling the underlying - PCRE matching function. - - REG_NOTEOL - - The PCRE_NOTEOL option is set when calling the underlying - PCRE matching function. - - The portion of the string that was matched, and also any - captured substrings, are returned via the pmatch argument, - which points to an array of nmatch structures of type - regmatch_t, containing the members rm_so and rm_eo. These - contain the offset to the first character of each substring - and the offset to the first character after the end of each - substring, respectively. The 0th element of the vector - relates to the entire portion of string that was matched; - subsequent elements relate to the capturing subpatterns of - the regular expression. Unused entries in the array have - both structure members set to -1. - - A successful match yields a zero return; various error codes - are defined in the header file, of which REG_NOMATCH is the - "expected" failure code. - - - -ERROR MESSAGES - The regerror() function maps a non-zero errorcode from - either regcomp or regexec to a printable message. If preg is - not NULL, the error should have arisen from the use of that - structure. A message terminated by a binary zero is placed - in errbuf. The length of the message, including the zero, is - limited to errbuf_size. The yield of the function is the - size of buffer needed to hold the whole message. - - - -STORAGE - Compiling a regular expression causes memory to be allocated - and associated with the preg structure. The function reg- - free() frees all such memory, after which preg may no longer - be used as a compiled expression. - - - -AUTHOR - Philip Hazel - University Computing Service, - New Museums Site, - Cambridge CB2 3QG, England. - Phone: +44 1223 334714 - - Copyright (c) 1997-2000 University of Cambridge. diff --git a/srclib/pcre/doc/pcreprecompile.3 b/srclib/pcre/doc/pcreprecompile.3 deleted file mode 100644 index f08939bae0..0000000000 --- a/srclib/pcre/doc/pcreprecompile.3 +++ /dev/null @@ -1,125 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "SAVING AND RE-USING PRECOMPILED PCRE PATTERNS" -.rs -.sp -If you are running an application that uses a large number of regular -expression patterns, it may be useful to store them in a precompiled form -instead of having to compile them every time the application is run. -If you are not using any private character tables (see the -.\" HREF -\fBpcre_maketables()\fP -.\" -documentation), this is relatively straightforward. If you are using private -tables, it is a little bit more complicated. -.P -If you save compiled patterns to a file, you can copy them to a different host -and run them there. This works even if the new host has the opposite endianness -to the one on which the patterns were compiled. There may be a small -performance penalty, but it should be insignificant. -. -. -.SH "SAVING A COMPILED PATTERN" -.rs -.sh -The value returned by \fBpcre_compile()\fP points to a single block of memory -that holds the compiled pattern and associated data. You can find the length of -this block in bytes by calling \fBpcre_fullinfo()\fP with an argument of -PCRE_INFO_SIZE. You can then save the data in any appropriate manner. Here is -sample code that compiles a pattern and writes it to a file. It assumes that -the variable \fIfd\fP refers to a file that is open for output: -.sp - int erroroffset, rc, size; - char *error; - pcre *re; -.sp - re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL); - if (re == NULL) { ... handle errors ... } - rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size); - if (rc < 0) { ... handle errors ... } - rc = fwrite(re, 1, size, fd); - if (rc != size) { ... handle errors ... } -.sp -In this example, the bytes that comprise the compiled pattern are copied -exactly. Note that this is binary data that may contain any of the 256 possible -byte values. On systems that make a distinction between binary and non-binary -data, be sure that the file is opened for binary output. -.P -If you want to write more than one pattern to a file, you will have to devise a -way of separating them. For binary data, preceding each pattern with its length -is probably the most straightforward approach. Another possibility is to write -out the data in hexadecimal instead of binary, one pattern to a line. -.P -Saving compiled patterns in a file is only one possible way of storing them for -later use. They could equally well be saved in a database, or in the memory of -some daemon process that passes them via sockets to the processes that want -them. -.P -If the pattern has been studied, it is also possible to save the study data in -a similar way to the compiled pattern itself. When studying generates -additional information, \fBpcre_study()\fP returns a pointer to a -\fBpcre_extra\fP data block. Its format is defined in the -.\" HTML -.\" -section on matching a pattern -.\" -in the -.\" HREF -\fBpcreapi\fP -.\" -documentation. The \fIstudy_data\fP field points to the binary study data, and -this is what you must save (not the \fBpcre_extra\fP block itself). The length -of the study data can be obtained by calling \fBpcre_fullinfo()\fP with an -argument of PCRE_INFO_STUDYSIZE. Remember to check that \fBpcre_study()\fP did -return a non-NULL value before trying to save the study data. -. -. -.SH "RE-USING A PRECOMPILED PATTERN" -.rs -.sp -Re-using a precompiled pattern is straightforward. Having reloaded it into main -memory, you pass its pointer to \fBpcre_exec()\fP in the usual way. This should -work even on another host, and even if that host has the opposite endianness to -the one where the pattern was compiled. -.P -However, if you passed a pointer to custom character tables when the pattern -was compiled (the \fItableptr\fP argument of \fBpcre_compile()\fP), you must -now pass a similar pointer to \fBpcre_exec()\fP, because the value saved with -the compiled pattern will obviously be nonsense. A field in a -\fBpcre_extra()\fP block is used to pass this data, as described in the -.\" HTML -.\" -section on matching a pattern -.\" -in the -.\" HREF -\fBpcreapi\fP -.\" -documentation. -.P -If you did not provide custom character tables when the pattern was compiled, -the pointer in the compiled pattern is NULL, which causes \fBpcre_exec()\fP to -use PCRE's internal tables. Thus, you do not need to take any special action at -run time in this case. -.P -If you saved study data with the compiled pattern, you need to create your own -\fBpcre_extra\fP data block and set the \fIstudy_data\fP field to point to the -reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in the -\fIflags\fP field to indicate that study data is present. Then pass the -\fBpcre_extra\fP block to \fBpcre_exec()\fP in the usual way. -. -. -.SH "COMPATIBILITY WITH DIFFERENT PCRE RELEASES" -.rs -.sp -The layout of the control block that is at the start of the data that makes up -a compiled pattern was changed for release 5.0. If you have any saved patterns -that were compiled with previous releases (not a facility that was previously -advertised), you will have to recompile them for release 5.0. However, from now -on, it should be possible to make changes in a compabible manner. -.P -.in 0 -Last updated: 10 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcresample.3 b/srclib/pcre/doc/pcresample.3 deleted file mode 100644 index 8d949a671e..0000000000 --- a/srclib/pcre/doc/pcresample.3 +++ /dev/null @@ -1,66 +0,0 @@ -.TH PCRE 3 -.SH NAME -PCRE - Perl-compatible regular expressions -.SH "PCRE SAMPLE PROGRAM" -.rs -.sp -A simple, complete demonstration program, to get you started with using PCRE, -is supplied in the file \fIpcredemo.c\fP in the PCRE distribution. -.P -The program compiles the regular expression that is its first argument, and -matches it against the subject string in its second argument. No PCRE options -are set, and default character tables are used. If matching succeeds, the -program outputs the portion of the subject that matched, together with the -contents of any captured substrings. -.P -If the -g option is given on the command line, the program then goes on to -check for further matches of the same regular expression in the same subject -string. The logic is a little bit tricky because of the possibility of matching -an empty string. Comments in the code explain what is going on. -.P -If PCRE is installed in the standard include and library directories for your -system, you should be able to compile the demonstration program using this -command: -.sp - gcc -o pcredemo pcredemo.c -lpcre -.sp -If PCRE is installed elsewhere, you may need to add additional options to the -command line. For example, on a Unix-like system that has PCRE installed in -\fI/usr/local\fP, you can compile the demonstration program using a command -like this: -.sp -.\" JOINSH - gcc -o pcredemo -I/usr/local/include pcredemo.c \e - -L/usr/local/lib -lpcre -.sp -Once you have compiled the demonstration program, you can run simple tests like -this: -.sp - ./pcredemo 'cat|dog' 'the cat sat on the mat' - ./pcredemo -g 'cat|dog' 'the dog sat on the cat' -.sp -Note that there is a much more comprehensive test program, called -.\" HREF -\fBpcretest\fP, -.\" -which supports many more facilities for testing regular expressions and the -PCRE library. The \fBpcredemo\fP program is provided as a simple coding -example. -.P -On some operating systems (e.g. Solaris), when PCRE is not installed in the -standard library directory, you may get an error like this when you try to run -\fBpcredemo\fP: -.sp - ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory -.sp -This is caused by the way shared library support works on those systems. You -need to add -.sp - -R/usr/local/lib -.sp -(for example) to the compile command to get round this problem. -.P -.in 0 -Last updated: 09 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcretest.1 b/srclib/pcre/doc/pcretest.1 deleted file mode 100644 index 0c06cb701e..0000000000 --- a/srclib/pcre/doc/pcretest.1 +++ /dev/null @@ -1,483 +0,0 @@ -.TH PCRETEST 1 -.SH NAME -pcretest - a program for testing Perl-compatible regular expressions. -.SH SYNOPSIS -.rs -.sp -.B pcretest "[-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]" -.ti +5n -.B "[destination]" -.P -\fBpcretest\fP was written as a test program for the PCRE regular expression -library itself, but it can also be used for experimenting with regular -expressions. This document describes the features of the test program; for -details of the regular expressions themselves, see the -.\" HREF -\fBpcrepattern\fP -.\" -documentation. For details of the PCRE library function calls and their -options, see the -.\" HREF -\fBpcreapi\fP -.\" -documentation. -. -. -.SH OPTIONS -.rs -.TP 10 -\fB-C\fP -Output the version number of the PCRE library, and all available information -about the optional features that are included, and then exit. -.TP 10 -\fB-d\fP -Behave as if each regex had the \fB/D\fP (debug) modifier; the internal -form is output after compilation. -.TP 10 -\fB-i\fP -Behave as if each regex had the \fB/I\fP modifier; information about the -compiled pattern is given after compilation. -.TP 10 -\fB-m\fP -Output the size of each compiled pattern after it has been compiled. This is -equivalent to adding \fB/M\fP to each regular expression. For compatibility -with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP. -.TP 10 -\fB-o\fP \fIosize\fP -Set the number of elements in the output vector that is used when calling -\fBpcre_exec()\fP to be \fIosize\fP. The default value is 45, which is enough -for 14 capturing subexpressions. The vector size can be changed for individual -matching calls by including \eO in the data line (see below). -.TP 10 -\fB-p\fP -Behave as if each regex has \fB/P\fP modifier; the POSIX wrapper API is used -to call PCRE. None of the other options has any effect when \fB-p\fP is set. -.TP 10 -\fB-t\fP -Run each compile, study, and match many times with a timer, and output -resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with -\fB-t\fP, because you will then get the size output a zillion times, and the -timing will be distorted. -. -. -.SH DESCRIPTION -.rs -.sp -If \fBpcretest\fP is given two filename arguments, it reads from the first and -writes to the second. If it is given only one filename argument, it reads from -that file and writes to stdout. Otherwise, it reads from stdin and writes to -stdout, and prompts for each line of input, using "re>" to prompt for regular -expressions, and "data>" to prompt for data lines. -.P -The program handles any number of sets of input on a single input file. Each -set starts with a regular expression, and continues with any number of data -lines to be matched against the pattern. -.P -Each data line is matched separately and independently. If you want to do -multiple-line matches, you have to use the \en escape sequence in a single line -of input to encode the newline characters. The maximum length of data line is -30,000 characters. -.P -An empty line signals the end of the data lines, at which point a new regular -expression is read. The regular expressions are given enclosed in any -non-alphanumeric delimiters other than backslash, for example -.sp - /(a|bc)x+yz/ -.sp -White space before the initial delimiter is ignored. A regular expression may -be continued over several input lines, in which case the newline characters are -included within it. It is possible to include the delimiter within the pattern -by escaping it, for example -.sp - /abc\e/def/ -.sp -If you do so, the escape and the delimiter form part of the pattern, but since -delimiters are always non-alphanumeric, this does not affect its interpretation. -If the terminating delimiter is immediately followed by a backslash, for -example, -.sp - /abc/\e -.sp -then a backslash is added to the end of the pattern. This is done to provide a -way of testing the error condition that arises if a pattern finishes with a -backslash, because -.sp - /abc\e/ -.sp -is interpreted as the first line of a pattern that starts with "abc/", causing -pcretest to read the next line as a continuation of the regular expression. -. -. -.SH "PATTERN MODIFIERS" -.rs -.sp -A pattern may be followed by any number of modifiers, which are mostly single -characters. Following Perl usage, these are referred to below as, for example, -"the \fB/i\fP modifier", even though the delimiter of the pattern need not -always be a slash, and no slash is used when writing modifiers. Whitespace may -appear between the final pattern delimiter and the first modifier, and between -the modifiers themselves. -.P -The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS, -PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when -\fBpcre_compile()\fP is called. These four modifier letters have the same -effect as they do in Perl. For example: -.sp - /caseless/i -.sp -The following table shows additional modifiers for setting PCRE options that do -not correspond to anything in Perl: -.sp - \fB/A\fP PCRE_ANCHORED - \fB/C\fP PCRE_AUTO_CALLOUT - \fB/E\fP PCRE_DOLLAR_ENDONLY - \fB/N\fP PCRE_NO_AUTO_CAPTURE - \fB/U\fP PCRE_UNGREEDY - \fB/X\fP PCRE_EXTRA -.sp -Searching for all possible matches within each subject string can be requested -by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called -again to search the remainder of the subject string. The difference between -\fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to -\fBpcre_exec()\fP to start searching at a new point within the entire string -(which is in effect what Perl does), whereas the latter passes over a shortened -substring. This makes a difference to the matching process if the pattern -begins with a lookbehind assertion (including \eb or \eB). -.P -If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an -empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED -flags set in order to search for another, non-empty, match at the same point. -If this second match fails, the start offset is advanced by one, and the normal -match is retried. This imitates the way Perl handles such cases when using the -\fB/g\fP modifier or the \fBsplit()\fP function. -.P -There are yet more modifiers for controlling the way \fBpcretest\fP -operates. -.P -The \fB/+\fP modifier requests that as well as outputting the substring that -matched the entire pattern, pcretest should in addition output the remainder of -the subject string. This is useful for tests where the subject contains -multiple copies of the same substring. -.P -The \fB/L\fP modifier must be followed directly by the name of a locale, for -example, -.sp - /pattern/Lfr_FR -.sp -For this reason, it must be the last modifier. The given locale is set, -\fBpcre_maketables()\fP is called to build a set of character tables for the -locale, and this is then passed to \fBpcre_compile()\fP when compiling the -regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables -pointer; that is, \fB/L\fP applies only to the expression on which it appears. -.P -The \fB/I\fP modifier requests that \fBpcretest\fP output information about the -compiled pattern (whether it is anchored, has a fixed first character, and -so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a -pattern. If the pattern is studied, the results of that are also output. -.P -The \fB/D\fP modifier is a PCRE debugging feature, which also assumes \fB/I\fP. -It causes the internal form of compiled regular expressions to be output after -compilation. If the pattern was studied, the information returned is also -output. -.P -The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the -fields in the compiled pattern that contain 2-byte and 4-byte numbers. This -facility is for testing the feature in PCRE that allows it to execute patterns -that were compiled on a host with a different endianness. This feature is not -available when the POSIX interface to PCRE is being used, that is, when the -\fB/P\fP pattern modifier is specified. See also the section about saving and -reloading compiled patterns below. -.P -The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the -expression has been compiled, and the results used when the expression is -matched. -.P -The \fB/M\fP modifier causes the size of memory block used to hold the compiled -pattern to be output. -.P -The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper -API rather than its native API. When this is done, all other modifiers except -\fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is -present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions -force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. -.P -The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8 -option set. This turns on support for UTF-8 character handling in PCRE, -provided that it was compiled with this support enabled. This modifier also -causes any non-printing characters in output strings to be printed using the -\ex{hh...} notation if they are valid UTF-8 sequences. -.P -If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to -call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the -checking of the string for UTF-8 validity. -. -. -.SH "DATA LINES" -.rs -.sp -Before each data line is passed to \fBpcre_exec()\fP, leading and trailing -whitespace is removed, and it is then scanned for \e escapes. Some of these are -pretty esoteric features, intended for checking out some of the more -complicated features of PCRE. If you are just testing "ordinary" regular -expressions, you probably don't need any of these. The following escapes are -recognized: -.sp - \ea alarm (= BEL) - \eb backspace - \ee escape - \ef formfeed - \en newline - \er carriage return - \et tab - \ev vertical tab - \ennn octal character (up to 3 octal digits) - \exhh hexadecimal character (up to 2 hex digits) -.\" JOIN - \ex{hh...} hexadecimal character, any number of digits - in UTF-8 mode - \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP - \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP -.\" JOIN - \eCdd call pcre_copy_substring() for substring dd - after a successful match (number less than 32) -.\" JOIN - \eCname call pcre_copy_named_substring() for substring - "name" after a successful match (name termin- - ated by next non alphanumeric character) -.\" JOIN - \eC+ show the current captured substrings at callout - time - \eC- do not supply a callout function -.\" JOIN - \eC!n return 1 instead of 0 when callout number n is - reached -.\" JOIN - \eC!n!m return 1 instead of 0 when callout number n is - reached for the nth time -.\" JOIN - \eC*n pass the number n (may be negative) as callout - data; this is used as the callout return value -.\" JOIN - \eGdd call pcre_get_substring() for substring dd - after a successful match (number less than 32) -.\" JOIN - \eGname call pcre_get_named_substring() for substring - "name" after a successful match (name termin- - ated by next non-alphanumeric character) -.\" JOIN - \eL call pcre_get_substringlist() after a - successful match - \eM discover the minimum MATCH_LIMIT setting - \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP -.\" JOIN - \eOdd set the size of the output vector passed to - \fBpcre_exec()\fP to dd (any number of digits) - \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP - \eS output details of memory get/free calls during matching - \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP -.\" JOIN - \e? pass the PCRE_NO_UTF8_CHECK option to - \fBpcre_exec()\fP - \e>dd start the match at offset dd (any number of digits); - this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP -.sp -A backslash followed by anything else just escapes the anything else. If the -very last character is a backslash, it is ignored. This gives a way of passing -an empty line as data, since a real empty line terminates the data input. -.P -If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with -different values in the \fImatch_limit\fP field of the \fBpcre_extra\fP data -structure, until it finds the minimum number that is needed for -\fBpcre_exec()\fP to complete. This number is a measure of the amount of -recursion and backtracking that takes place, and checking it out can be -instructive. For most simple matches, the number is quite small, but for -patterns with very large numbers of matching possibilities, it can become large -very quickly with increasing length of subject string. -.P -When \eO is used, the value specified may be higher or lower than the size set -by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to -the call of \fBpcre_exec()\fP for the line in which it appears. -.P -If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper -API to be used, only \eB and \eZ have any effect, causing REG_NOTBOL and -REG_NOTEOL to be passed to \fBregexec()\fP respectively. -.P -The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use -of the \fB/8\fP modifier on the pattern. It is recognized always. There may be -any number of hexadecimal digits inside the braces. The result is from one to -six bytes, encoded according to the UTF-8 rules. -. -. -.SH "OUTPUT FROM PCRETEST" -.rs -.sp -When a match succeeds, pcretest outputs the list of captured substrings that -\fBpcre_exec()\fP returns, starting with number 0 for the string that matched -the whole pattern. Otherwise, it outputs "No match" or "Partial match" -when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL, -respectively, and otherwise the PCRE negative error number. Here is an example -of an interactive pcretest run. -.sp - $ pcretest - PCRE version 5.00 07-Sep-2004 -.sp - re> /^abc(\ed+)/ - data> abc123 - 0: abc123 - 1: 123 - data> xyz - No match -.sp -If the strings contain any non-printing characters, they are output as \e0x -escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the -pattern. If the pattern has the \fB/+\fP modifier, the output for substring 0 -is followed by the the rest of the subject string, identified by "0+" like -this: -.sp - re> /cat/+ - data> cataract - 0: cat - 0+ aract -.sp -If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive -matching attempts are output in sequence, like this: -.sp - re> /\eBi(\ew\ew)/g - data> Mississippi - 0: iss - 1: ss - 0: iss - 1: ss - 0: ipp - 1: pp -.sp -"No match" is output only if the first match attempt fails. -.P -If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a -data line that is successfully matched, the substrings extracted by the -convenience functions are output with C, G, or L after the string number -instead of a colon. This is in addition to the normal full list. The string -length (that is, the return from the extraction function) is given in -parentheses after each string for \fB\eC\fP and \fB\eG\fP. -.P -Note that while patterns can be continued over several lines (a plain ">" -prompt is used for continuations), data lines may not. However newlines can be -included in data by means of the \en escape. -. -. -.SH CALLOUTS -.rs -.sp -If the pattern contains any callout requests, \fBpcretest\fP's callout function -is called during matching. By default, it displays the callout number, the -start and current positions in the text at the callout time, and the next -pattern item to be tested. For example, the output -.sp - --->pqrabcdef - 0 ^ ^ \ed -.sp -indicates that callout number 0 occurred for a match attempt starting at the -fourth character of the subject string, when the pointer was at the seventh -character of the data, and when the next pattern item was \ed. Just one -circumflex is output if the start and current positions are the same. -.P -Callouts numbered 255 are assumed to be automatic callouts, inserted as a -result of the \fB/C\fP pattern modifier. In this case, instead of showing the -callout number, the offset in the pattern, preceded by a plus, is output. For -example: -.sp - re> /\ed?[A-E]\e*/C - data> E* - --->E* - +0 ^ \ed? - +3 ^ [A-E] - +8 ^^ \e* - +10 ^ ^ - 0: E* -.sp -The callout function in \fBpcretest\fP returns zero (carry on matching) by -default, but you can use an \eC item in a data line (as described above) to -change this. -.P -Inserting callouts can be helpful when using \fBpcretest\fP to check -complicated regular expressions. For further information about callouts, see -the -.\" HREF -\fBpcrecallout\fP -.\" -documentation. -. -. -.SH "SAVING AND RELOADING COMPILED PATTERNS" -.rs -.sp -The facilities described in this section are not available when the POSIX -inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is -specified. -.P -When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a -compiled pattern to a file, by following the modifiers with > and a file name. -For example: -.sp - /pattern/im >/some/file -.sp -See the -.\" HREF -\fBpcreprecompile\fP -.\" -documentation for a discussion about saving and re-using compiled patterns. -.P -The data that is written is binary. The first eight bytes are the length of the -compiled pattern data followed by the length of the optional study data, each -written as four bytes in big-endian order (most significant byte first). If -there is no study data (either the pattern was not studied, or studying did not -return any data), the second length is zero. The lengths are followed by an -exact copy of the compiled pattern. If there is additional study data, this -follows immediately after the compiled pattern. After writing the file, -\fBpcretest\fP expects to read a new pattern. -.P -A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file -name instead of a pattern. The name of the file must not contain a < character, -as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by < -characters. -For example: -.sp - re> -.br -University Computing Service, -.br -Cambridge CB2 3QG, England. -.P -.in 0 -Last updated: 10 September 2004 -.br -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/pcretest.html b/srclib/pcre/doc/pcretest.html deleted file mode 100644 index 918e6dec2b..0000000000 --- a/srclib/pcre/doc/pcretest.html +++ /dev/null @@ -1,369 +0,0 @@ - - -pcretest specification - - -

    pcretest specification

    -This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page in case the -conversion went wrong. - -
  • NAME -

    -pcretest - a program for testing Perl-compatible regular expressions. -

    -
  • SYNOPSIS -

    -pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination] -

    -

    -pcretest was written as a test program for the PCRE regular expression -library itself, but it can also be used for experimenting with regular -expressions. This man page describes the features of the test program; for -details of the regular expressions themselves, see the pcre man page. -

    -
  • OPTIONS -

    --d -Behave as if each regex had the /D modifier (see below); the internal -form is output after compilation. -

    -

    --i -Behave as if each regex had the /I modifier; information about the -compiled pattern is given after compilation. -

    -

    --m -Output the size of each compiled pattern after it has been compiled. This is -equivalent to adding /M to each regular expression. For compatibility with -earlier versions of pcretest, -s is a synonym for -m. -

    -

    --o osize -Set the number of elements in the output vector that is used when calling PCRE -to be osize. The default value is 45, which is enough for 14 capturing -subexpressions. The vector size can be changed for individual matching calls by -including \O in the data line (see below). -

    -

    --p -Behave as if each regex has /P modifier; the POSIX wrapper API is used -to call PCRE. None of the other options has any effect when -p is set. -

    -

    --t -Run each compile, study, and match 20000 times with a timer, and output -resulting time per compile or match (in milliseconds). Do not set -t with --m, because you will then get the size output 20000 times and the timing -will be distorted. -

    -
  • DESCRIPTION -

    -If pcretest is given two filename arguments, it reads from the first and -writes to the second. If it is given only one filename argument, it reads from -that file and writes to stdout. Otherwise, it reads from stdin and writes to -stdout, and prompts for each line of input, using "re>" to prompt for regular -expressions, and "data>" to prompt for data lines. -

    -

    -The program handles any number of sets of input on a single input file. Each -set starts with a regular expression, and continues with any number of data -lines to be matched against the pattern. An empty line signals the end of the -data lines, at which point a new regular expression is read. The regular -expressions are given enclosed in any non-alphameric delimiters other than -backslash, for example -

    -

    -

    -  /(a|bc)x+yz/
-
    -

    -

    -White space before the initial delimiter is ignored. A regular expression may -be continued over several input lines, in which case the newline characters are -included within it. It is possible to include the delimiter within the pattern -by escaping it, for example -

    -

    -

    -  /abc\/def/
-
    -

    -

    -If you do so, the escape and the delimiter form part of the pattern, but since -delimiters are always non-alphameric, this does not affect its interpretation. -If the terminating delimiter is immediately followed by a backslash, for -example, -

    -

    -

    -  /abc/\
-
    -

    -

    -then a backslash is added to the end of the pattern. This is done to provide a -way of testing the error condition that arises if a pattern finishes with a -backslash, because -

    -

    -

    -  /abc\/
-
    -

    -

    -is interpreted as the first line of a pattern that starts with "abc/", causing -pcretest to read the next line as a continuation of the regular expression. -

    -
  • PATTERN MODIFIERS -

    -The pattern may be followed by i, m, s, or x to set the -PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, -respectively. For example: -

    -

    -

    -  /caseless/i
-
    -

    -

    -These modifier letters have the same effect as they do in Perl. There are -others which set PCRE options that do not correspond to anything in Perl: -/A, /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and -PCRE_EXTRA respectively. -

    -

    -Searching for all possible matches within each subject string can be requested -by the /g or /G modifier. After finding a match, PCRE is called -again to search the remainder of the subject string. The difference between -/g and /G is that the former uses the startoffset argument to -pcre_exec() to start searching at a new point within the entire string -(which is in effect what Perl does), whereas the latter passes over a shortened -substring. This makes a difference to the matching process if the pattern -begins with a lookbehind assertion (including \b or \B). -

    -

    -If any call to pcre_exec() in a /g or /G sequence matches an -empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED -flags set in order to search for another, non-empty, match at the same point. -If this second match fails, the start offset is advanced by one, and the normal -match is retried. This imitates the way Perl handles such cases when using the -/g modifier or the split() function. -

    -

    -There are a number of other modifiers for controlling the way pcretest -operates. -

    -

    -The /+ modifier requests that as well as outputting the substring that -matched the entire pattern, pcretest should in addition output the remainder of -the subject string. This is useful for tests where the subject contains -multiple copies of the same substring. -

    -

    -The /L modifier must be followed directly by the name of a locale, for -example, -

    -

    -

    -  /pattern/Lfr
-
    -

    -

    -For this reason, it must be the last modifier letter. The given locale is set, -pcre_maketables() is called to build a set of character tables for the -locale, and this is then passed to pcre_compile() when compiling the -regular expression. Without an /L modifier, NULL is passed as the tables -pointer; that is, /L applies only to the expression on which it appears. -

    -

    -The /I modifier requests that pcretest output information about the -compiled expression (whether it is anchored, has a fixed first character, and -so on). It does this by calling pcre_fullinfo() after compiling an -expression, and outputting the information it gets back. If the pattern is -studied, the results of that are also output. -

    -

    -The /D modifier is a PCRE debugging feature, which also assumes /I. -It causes the internal form of compiled regular expressions to be output after -compilation. -

    -

    -The /S modifier causes pcre_study() to be called after the -expression has been compiled, and the results used when the expression is -matched. -

    -

    -The /M modifier causes the size of memory block used to hold the compiled -pattern to be output. -

    -

    -The /P modifier causes pcretest to call PCRE via the POSIX wrapper -API rather than its native API. When this is done, all other modifiers except -/i, /m, and /+ are ignored. REG_ICASE is set if /i is -present, and REG_NEWLINE is set if /m is present. The wrapper functions -force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. -

    -

    -The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 -option set. This turns on the (currently incomplete) support for UTF-8 -character handling in PCRE, provided that it was compiled with this support -enabled. This modifier also causes any non-printing characters in output -strings to be printed using the \x{hh...} notation if they are valid UTF-8 -sequences. -

    -
  • DATA LINES -

    -Before each data line is passed to pcre_exec(), leading and trailing -whitespace is removed, and it is then scanned for \ escapes. The following are -recognized: -

    -

    -

    -  \a         alarm (= BEL)
-  \b         backspace
-  \e         escape
-  \f         formfeed
-  \n         newline
-  \r         carriage return
-  \t         tab
-  \v         vertical tab
-  \nnn       octal character (up to 3 octal digits)
-  \xhh       hexadecimal character (up to 2 hex digits)
-  \x{hh...}  hexadecimal UTF-8 character
-
    -

    -

    -

    -  \A         pass the PCRE_ANCHORED option to pcre_exec()
-  \B         pass the PCRE_NOTBOL option to pcre_exec()
-  \Cdd       call pcre_copy_substring() for substring dd
-                after a successful match (any decimal number
-                less than 32)
-  \Gdd       call pcre_get_substring() for substring dd
-                after a successful match (any decimal number
-                less than 32)
-  \L         call pcre_get_substringlist() after a
-                successful match
-  \N         pass the PCRE_NOTEMPTY option to pcre_exec()
-  \Odd       set the size of the output vector passed to
-                pcre_exec() to dd (any number of decimal
-                digits)
-  \Z         pass the PCRE_NOTEOL option to pcre_exec()
-
    -

    -

    -When \O is used, it may be higher or lower than the size set by the -O -option (or defaulted to 45); \O applies only to the call of pcre_exec() -for the line in which it appears. -

    -

    -A backslash followed by anything else just escapes the anything else. If the -very last character is a backslash, it is ignored. This gives a way of passing -an empty line as data, since a real empty line terminates the data input. -

    -

    -If /P was present on the regex, causing the POSIX wrapper API to be used, -only \B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL -to be passed to regexec() respectively. -

    -

    -The use of \x{hh...} to represent UTF-8 characters is not dependent on the use -of the /8 modifier on the pattern. It is recognized always. There may be -any number of hexadecimal digits inside the braces. The result is from one to -six bytes, encoded according to the UTF-8 rules. -

    -
  • OUTPUT FROM PCRETEST -

    -When a match succeeds, pcretest outputs the list of captured substrings that -pcre_exec() returns, starting with number 0 for the string that matched -the whole pattern. Here is an example of an interactive pcretest run. -

    -

    -

    -  $ pcretest
-  PCRE version 2.06 08-Jun-1999
-
    -

    -

    -

    -    re> /^abc(\d+)/
-  data> abc123
-   0: abc123
-   1: 123
-  data> xyz
-  No match
-
    -

    -

    -If the strings contain any non-printing characters, they are output as \0x -escapes, or as \x{...} escapes if the /8 modifier was present on the -pattern. If the pattern has the /+ modifier, then the output for -substring 0 is followed by the the rest of the subject string, identified by -"0+" like this: -

    -

    -

    -    re> /cat/+
-  data> cataract
-   0: cat
-   0+ aract
-
    -

    -

    -If the pattern has the /g or /G modifier, the results of successive -matching attempts are output in sequence, like this: -

    -

    -

    -    re> /\Bi(\w\w)/g
-  data> Mississippi
-   0: iss
-   1: ss
-   0: iss
-   1: ss
-   0: ipp
-   1: pp
-
    -

    -

    -"No match" is output only if the first match attempt fails. -

    -

    -If any of the sequences \C, \G, or \L are present in a -data line that is successfully matched, the substrings extracted by the -convenience functions are output with C, G, or L after the string number -instead of a colon. This is in addition to the normal full list. The string -length (that is, the return from the extraction function) is given in -parentheses after each string for \C and \G. -

    -

    -Note that while patterns can be continued over several lines (a plain ">" -prompt is used for continuations), data lines may not. However newlines can be -included in data by means of the \n escape. -

    -
  • AUTHOR -

    -Philip Hazel <ph10@cam.ac.uk> -
    -University Computing Service, -
    -New Museums Site, -
    -Cambridge CB2 3QG, England. -
    -Phone: +44 1223 334714 -

    -

    -Last updated: 15 August 2001 -
    -Copyright (c) 1997-2001 University of Cambridge. diff --git a/srclib/pcre/doc/pcretest.txt b/srclib/pcre/doc/pcretest.txt deleted file mode 100644 index 7da68894a1..0000000000 --- a/srclib/pcre/doc/pcretest.txt +++ /dev/null @@ -1,450 +0,0 @@ -PCRETEST(1) PCRETEST(1) - - - -NAME - pcretest - a program for testing Perl-compatible regular expressions. - -SYNOPSIS - - pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source] - [destination] - - pcretest was written as a test program for the PCRE regular expression - library itself, but it can also be used for experimenting with regular - expressions. This document describes the features of the test program; - for details of the regular expressions themselves, see the pcrepattern - documentation. For details of the PCRE library function calls and their - options, see the pcreapi documentation. - - -OPTIONS - - -C Output the version number of the PCRE library, and all avail- - able information about the optional features that are - included, and then exit. - - -d Behave as if each regex had the /D (debug) modifier; the - internal form is output after compilation. - - -i Behave as if each regex had the /I modifier; information - about the compiled pattern is given after compilation. - - -m Output the size of each compiled pattern after it has been - compiled. This is equivalent to adding /M to each regular - expression. For compatibility with earlier versions of - pcretest, -s is a synonym for -m. - - -o osize Set the number of elements in the output vector that is used - when calling pcre_exec() to be osize. The default value is - 45, which is enough for 14 capturing subexpressions. The vec- - tor size can be changed for individual matching calls by - including \O in the data line (see below). - - -p Behave as if each regex has /P modifier; the POSIX wrapper - API is used to call PCRE. None of the other options has any - effect when -p is set. - - -t Run each compile, study, and match many times with a timer, - and output resulting time per compile or match (in millisec- - onds). Do not set -m with -t, because you will then get the - size output a zillion times, and the timing will be dis- - torted. - - -DESCRIPTION - - If pcretest is given two filename arguments, it reads from the first - and writes to the second. If it is given only one filename argument, it - reads from that file and writes to stdout. Otherwise, it reads from - stdin and writes to stdout, and prompts for each line of input, using - "re>" to prompt for regular expressions, and "data>" to prompt for data - lines. - - The program handles any number of sets of input on a single input file. - Each set starts with a regular expression, and continues with any num- - ber of data lines to be matched against the pattern. - - Each data line is matched separately and independently. If you want to - do multiple-line matches, you have to use the \n escape sequence in a - single line of input to encode the newline characters. The maximum - length of data line is 30,000 characters. - - An empty line signals the end of the data lines, at which point a new - regular expression is read. The regular expressions are given enclosed - in any non-alphanumeric delimiters other than backslash, for example - - /(a|bc)x+yz/ - - White space before the initial delimiter is ignored. A regular expres- - sion may be continued over several input lines, in which case the new- - line characters are included within it. It is possible to include the - delimiter within the pattern by escaping it, for example - - /abc\/def/ - - If you do so, the escape and the delimiter form part of the pattern, - but since delimiters are always non-alphanumeric, this does not affect - its interpretation. If the terminating delimiter is immediately fol- - lowed by a backslash, for example, - - /abc/\ - - then a backslash is added to the end of the pattern. This is done to - provide a way of testing the error condition that arises if a pattern - finishes with a backslash, because - - /abc\/ - - is interpreted as the first line of a pattern that starts with "abc/", - causing pcretest to read the next line as a continuation of the regular - expression. - - -PATTERN MODIFIERS - - A pattern may be followed by any number of modifiers, which are mostly - single characters. Following Perl usage, these are referred to below - as, for example, "the /i modifier", even though the delimiter of the - pattern need not always be a slash, and no slash is used when writing - modifiers. Whitespace may appear between the final pattern delimiter - and the first modifier, and between the modifiers themselves. - - The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE, - PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com- - pile() is called. These four modifier letters have the same effect as - they do in Perl. For example: - - /caseless/i - - The following table shows additional modifiers for setting PCRE options - that do not correspond to anything in Perl: - - /A PCRE_ANCHORED - /C PCRE_AUTO_CALLOUT - /E PCRE_DOLLAR_ENDONLY - /N PCRE_NO_AUTO_CAPTURE - /U PCRE_UNGREEDY - /X PCRE_EXTRA - - Searching for all possible matches within each subject string can be - requested by the /g or /G modifier. After finding a match, PCRE is - called again to search the remainder of the subject string. The differ- - ence between /g and /G is that the former uses the startoffset argument - to pcre_exec() to start searching at a new point within the entire - string (which is in effect what Perl does), whereas the latter passes - over a shortened substring. This makes a difference to the matching - process if the pattern begins with a lookbehind assertion (including \b - or \B). - - If any call to pcre_exec() in a /g or /G sequence matches an empty - string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED - flags set in order to search for another, non-empty, match at the same - point. If this second match fails, the start offset is advanced by - one, and the normal match is retried. This imitates the way Perl han- - dles such cases when using the /g modifier or the split() function. - - There are yet more modifiers for controlling the way pcretest operates. - - The /+ modifier requests that as well as outputting the substring that - matched the entire pattern, pcretest should in addition output the - remainder of the subject string. This is useful for tests where the - subject contains multiple copies of the same substring. - - The /L modifier must be followed directly by the name of a locale, for - example, - - /pattern/Lfr_FR - - For this reason, it must be the last modifier. The given locale is set, - pcre_maketables() is called to build a set of character tables for the - locale, and this is then passed to pcre_compile() when compiling the - regular expression. Without an /L modifier, NULL is passed as the - tables pointer; that is, /L applies only to the expression on which it - appears. - - The /I modifier requests that pcretest output information about the - compiled pattern (whether it is anchored, has a fixed first character, - and so on). It does this by calling pcre_fullinfo() after compiling a - pattern. If the pattern is studied, the results of that are also out- - put. - - The /D modifier is a PCRE debugging feature, which also assumes /I. It - causes the internal form of compiled regular expressions to be output - after compilation. If the pattern was studied, the information returned - is also output. - - The /F modifier causes pcretest to flip the byte order of the fields in - the compiled pattern that contain 2-byte and 4-byte numbers. This - facility is for testing the feature in PCRE that allows it to execute - patterns that were compiled on a host with a different endianness. This - feature is not available when the POSIX interface to PCRE is being - used, that is, when the /P pattern modifier is specified. See also the - section about saving and reloading compiled patterns below. - - The /S modifier causes pcre_study() to be called after the expression - has been compiled, and the results used when the expression is matched. - - The /M modifier causes the size of memory block used to hold the com- - piled pattern to be output. - - The /P modifier causes pcretest to call PCRE via the POSIX wrapper API - rather than its native API. When this is done, all other modifiers - except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present, - and REG_NEWLINE is set if /m is present. The wrapper functions force - PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. - - The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option - set. This turns on support for UTF-8 character handling in PCRE, pro- - vided that it was compiled with this support enabled. This modifier - also causes any non-printing characters in output strings to be printed - using the \x{hh...} notation if they are valid UTF-8 sequences. - - If the /? modifier is used with /8, it causes pcretest to call - pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the - checking of the string for UTF-8 validity. - - -DATA LINES - - Before each data line is passed to pcre_exec(), leading and trailing - whitespace is removed, and it is then scanned for \ escapes. Some of - these are pretty esoteric features, intended for checking out some of - the more complicated features of PCRE. If you are just testing "ordi- - nary" regular expressions, you probably don't need any of these. The - following escapes are recognized: - - \a alarm (= BEL) - \b backspace - \e escape - \f formfeed - \n newline - \r carriage return - \t tab - \v vertical tab - \nnn octal character (up to 3 octal digits) - \xhh hexadecimal character (up to 2 hex digits) - \x{hh...} hexadecimal character, any number of digits - in UTF-8 mode - \A pass the PCRE_ANCHORED option to pcre_exec() - \B pass the PCRE_NOTBOL option to pcre_exec() - \Cdd call pcre_copy_substring() for substring dd - after a successful match (number less than 32) - \Cname call pcre_copy_named_substring() for substring - "name" after a successful match (name termin- - ated by next non alphanumeric character) - \C+ show the current captured substrings at callout - time - \C- do not supply a callout function - \C!n return 1 instead of 0 when callout number n is - reached - \C!n!m return 1 instead of 0 when callout number n is - reached for the nth time - \C*n pass the number n (may be negative) as callout - data; this is used as the callout return value - \Gdd call pcre_get_substring() for substring dd - after a successful match (number less than 32) - \Gname call pcre_get_named_substring() for substring - "name" after a successful match (name termin- - ated by next non-alphanumeric character) - \L call pcre_get_substringlist() after a - successful match - \M discover the minimum MATCH_LIMIT setting - \N pass the PCRE_NOTEMPTY option to pcre_exec() - \Odd set the size of the output vector passed to - pcre_exec() to dd (any number of digits) - \P pass the PCRE_PARTIAL option to pcre_exec() - \S output details of memory get/free calls during matching - \Z pass the PCRE_NOTEOL option to pcre_exec() - \? pass the PCRE_NO_UTF8_CHECK option to - pcre_exec() - \>dd start the match at offset dd (any number of digits); - this sets the startoffset argument for pcre_exec() - - A backslash followed by anything else just escapes the anything else. - If the very last character is a backslash, it is ignored. This gives a - way of passing an empty line as data, since a real empty line termi- - nates the data input. - - If \M is present, pcretest calls pcre_exec() several times, with dif- - ferent values in the match_limit field of the pcre_extra data struc- - ture, until it finds the minimum number that is needed for pcre_exec() - to complete. This number is a measure of the amount of recursion and - backtracking that takes place, and checking it out can be instructive. - For most simple matches, the number is quite small, but for patterns - with very large numbers of matching possibilities, it can become large - very quickly with increasing length of subject string. - - When \O is used, the value specified may be higher or lower than the - size set by the -O command line option (or defaulted to 45); \O applies - only to the call of pcre_exec() for the line in which it appears. - - If the /P modifier was present on the pattern, causing the POSIX wrap- - per API to be used, only \B and \Z have any effect, causing REG_NOTBOL - and REG_NOTEOL to be passed to regexec() respectively. - - The use of \x{hh...} to represent UTF-8 characters is not dependent on - the use of the /8 modifier on the pattern. It is recognized always. - There may be any number of hexadecimal digits inside the braces. The - result is from one to six bytes, encoded according to the UTF-8 rules. - - -OUTPUT FROM PCRETEST - - When a match succeeds, pcretest outputs the list of captured substrings - that pcre_exec() returns, starting with number 0 for the string that - matched the whole pattern. Otherwise, it outputs "No match" or "Partial - match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR- - TIAL, respectively, and otherwise the PCRE negative error number. Here - is an example of an interactive pcretest run. - - $ pcretest - PCRE version 5.00 07-Sep-2004 - - re> /^abc(\d+)/ - data> abc123 - 0: abc123 - 1: 123 - data> xyz - No match - - If the strings contain any non-printing characters, they are output as - \0x escapes, or as \x{...} escapes if the /8 modifier was present on - the pattern. If the pattern has the /+ modifier, the output for sub- - string 0 is followed by the the rest of the subject string, identified - by "0+" like this: - - re> /cat/+ - data> cataract - 0: cat - 0+ aract - - If the pattern has the /g or /G modifier, the results of successive - matching attempts are output in sequence, like this: - - re> /\Bi(\w\w)/g - data> Mississippi - 0: iss - 1: ss - 0: iss - 1: ss - 0: ipp - 1: pp - - "No match" is output only if the first match attempt fails. - - If any of the sequences \C, \G, or \L are present in a data line that - is successfully matched, the substrings extracted by the convenience - functions are output with C, G, or L after the string number instead of - a colon. This is in addition to the normal full list. The string length - (that is, the return from the extraction function) is given in paren- - theses after each string for \C and \G. - - Note that while patterns can be continued over several lines (a plain - ">" prompt is used for continuations), data lines may not. However new- - lines can be included in data by means of the \n escape. - - -CALLOUTS - - If the pattern contains any callout requests, pcretest's callout func- - tion is called during matching. By default, it displays the callout - number, the start and current positions in the text at the callout - time, and the next pattern item to be tested. For example, the output - - --->pqrabcdef - 0 ^ ^ \d - - indicates that callout number 0 occurred for a match attempt starting - at the fourth character of the subject string, when the pointer was at - the seventh character of the data, and when the next pattern item was - \d. Just one circumflex is output if the start and current positions - are the same. - - Callouts numbered 255 are assumed to be automatic callouts, inserted as - a result of the /C pattern modifier. In this case, instead of showing - the callout number, the offset in the pattern, preceded by a plus, is - output. For example: - - re> /\d?[A-E]\*/C - data> E* - --->E* - +0 ^ \d? - +3 ^ [A-E] - +8 ^^ \* - +10 ^ ^ - 0: E* - - The callout function in pcretest returns zero (carry on matching) by - default, but you can use an \C item in a data line (as described above) - to change this. - - Inserting callouts can be helpful when using pcretest to check compli- - cated regular expressions. For further information about callouts, see - the pcrecallout documentation. - - -SAVING AND RELOADING COMPILED PATTERNS - - The facilities described in this section are not available when the - POSIX inteface to PCRE is being used, that is, when the /P pattern mod- - ifier is specified. - - When the POSIX interface is not in use, you can cause pcretest to write - a compiled pattern to a file, by following the modifiers with > and a - file name. For example: - - /pattern/im >/some/file - - See the pcreprecompile documentation for a discussion about saving and - re-using compiled patterns. - - The data that is written is binary. The first eight bytes are the - length of the compiled pattern data followed by the length of the - optional study data, each written as four bytes in big-endian order - (most significant byte first). If there is no study data (either the - pattern was not studied, or studying did not return any data), the sec- - ond length is zero. The lengths are followed by an exact copy of the - compiled pattern. If there is additional study data, this follows imme- - diately after the compiled pattern. After writing the file, pcretest - expects to read a new pattern. - - A saved pattern can be reloaded into pcretest by specifing < and a file - name instead of a pattern. The name of the file must not contain a < - character, as otherwise pcretest will interpret the line as a pattern - delimited by < characters. For example: - - re> - University Computing Service, - Cambridge CB2 3QG, England. - -Last updated: 10 September 2004 -Copyright (c) 1997-2004 University of Cambridge. diff --git a/srclib/pcre/doc/perltest.txt b/srclib/pcre/doc/perltest.txt deleted file mode 100644 index f1d2c15961..0000000000 --- a/srclib/pcre/doc/perltest.txt +++ /dev/null @@ -1,33 +0,0 @@ -The perltest program --------------------- - -The perltest program tests Perl's regular expressions; it has the same -specification as pcretest, and so can be given identical input, except that -input patterns can be followed only by Perl's lower case modifiers and /+ (as -used by pcretest), which is recognized and handled by the program. - -The data lines are processed as Perl double-quoted strings, so if they contain -" $ or @ characters, these have to be escaped. For this reason, all such -characters in testinput1 and testinput4 are escaped so that they can be used -for perltest as well as for pcretest. The special upper case pattern -modifiers such as /A that pcretest recognizes, and its special data line -escapes, are not used in these files. The output should be identical, apart -from the initial identifying banner. - -The perltest script can also test UTF-8 features. It works as is for Perl 5.8 -or higher. It recognizes the special modifier /8 that pcretest uses to invoke -UTF-8 functionality. The testinput4 file can be fed to perltest to run -compatible UTF-8 tests. - -For Perl 5.6, perltest won't work unmodified for the UTF-8 tests. You need to -uncomment the "use utf8" lines that it contains. It is best to do this on a -copy of the script, because for non-UTF-8 tests, these lines should remain -commented out. - -The other testinput files are not suitable for feeding to perltest, since they -make use of the special upper case modifiers and escapes that pcretest uses to -test some features of PCRE. Some of these files also contains malformed regular -expressions, in order to check that PCRE diagnoses them correctly. - -Philip Hazel -September 2004 diff --git a/srclib/pcre/doc/pgrep.1 b/srclib/pcre/doc/pgrep.1 deleted file mode 100644 index d9e9b575e0..0000000000 --- a/srclib/pcre/doc/pgrep.1 +++ /dev/null @@ -1,76 +0,0 @@ -.TH PGREP 1 -.SH NAME -pgrep - a grep with Perl-compatible regular expressions. -.SH SYNOPSIS -.B pgrep [-Vchilnsvx] pattern [file] ... - - -.SH DESCRIPTION -\fBpgrep\fR searches files for character patterns, in the same way as other -grep commands do, but it uses the PCRE regular expression library to support -patterns that are compatible with the regular expressions of Perl 5. See -\fBpcre(3)\fR for a full description of syntax and semantics. - -If no files are specified, \fBpgrep\fR reads the standard input. By default, -each line that matches the pattern is copied to the standard output, and if -there is more than one file, the file name is printed before each line of -output. However, there are options that can change how \fBpgrep\fR behaves. - -Lines are limited to BUFSIZ characters. BUFSIZ is defined in \fB\fR. -The newline character is removed from the end of each line before it is matched -against the pattern. - - -.SH OPTIONS -.TP 10 -\fB-V\fR -Write the version number of the PCRE library being used to the standard error -stream. -.TP -\fB-c\fR -Do not print individual lines; instead just print a count of the number of -lines that would otherwise have been printed. If several files are given, a -count is printed for each of them. -.TP -\fB-h\fR -Suppress printing of filenames when searching multiple files. -.TP -\fB-i\fR -Ignore upper/lower case distinctions during comparisons. -.TP -\fB-l\fR -Instead of printing lines from the files, just print the names of the files -containing lines that would have been printed. Each file name is printed -once, on a separate line. -.TP -\fB-n\fR -Precede each line by its line number in the file. -.TP -\fB-s\fR -Work silently, that is, display nothing except error messages. -The exit status indicates whether any matches were found. -.TP -\fB-v\fR -Invert the sense of the match, so that lines which do \fInot\fR match the -pattern are now the ones that are found. -.TP -\fB-x\fR -Force the pattern to be anchored (it must start matching at the beginning of -the line) and in addition, require it to match the entire line. This is -equivalent to having ^ and $ characters at the start and end of each -alternative branch in the regular expression. - - -.SH SEE ALSO -\fBpcre(3)\fR, Perl 5 documentation - - -.SH DIAGNOSTICS -Exit status is 0 if any matches were found, 1 if no matches were found, and 2 -for syntax errors or inacessible files (even if matches were found). - - -.SH AUTHOR -Philip Hazel -.br -Copyright (c) 1997-1999 University of Cambridge. diff --git a/srclib/pcre/doc/pgrep.html b/srclib/pcre/doc/pgrep.html deleted file mode 100644 index 54efed6785..0000000000 --- a/srclib/pcre/doc/pgrep.html +++ /dev/null @@ -1,105 +0,0 @@ - - -pgrep specification - - -

    pgrep specification

    -This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page in case the -conversion went wrong. - -
  • NAME -

    -pgrep - a grep with Perl-compatible regular expressions. -

    -
  • SYNOPSIS -

    -pgrep [-Vchilnsvx] pattern [file] ... -

    -
  • DESCRIPTION -

    -pgrep searches files for character patterns, in the same way as other -grep commands do, but it uses the PCRE regular expression library to support -patterns that are compatible with the regular expressions of Perl 5. See -pcre(3) for a full description of syntax and semantics. -

    -

    -If no files are specified, pgrep reads the standard input. By default, -each line that matches the pattern is copied to the standard output, and if -there is more than one file, the file name is printed before each line of -output. However, there are options that can change how pgrep behaves. -

    -

    -Lines are limited to BUFSIZ characters. BUFSIZ is defined in <stdio.h>. -The newline character is removed from the end of each line before it is matched -against the pattern. -

    -
  • OPTIONS -

    --V -Write the version number of the PCRE library being used to the standard error -stream. -

    -

    --c -Do not print individual lines; instead just print a count of the number of -lines that would otherwise have been printed. If several files are given, a -count is printed for each of them. -

    -

    --h -Suppress printing of filenames when searching multiple files. -

    -

    --i -Ignore upper/lower case distinctions during comparisons. -

    -

    --l -Instead of printing lines from the files, just print the names of the files -containing lines that would have been printed. Each file name is printed -once, on a separate line. -

    -

    --n -Precede each line by its line number in the file. -

    -

    --s -Work silently, that is, display nothing except error messages. -The exit status indicates whether any matches were found. -

    -

    --v -Invert the sense of the match, so that lines which do not match the -pattern are now the ones that are found. -

    -

    --x -Force the pattern to be anchored (it must start matching at the beginning of -the line) and in addition, require it to match the entire line. This is -equivalent to having ^ and $ characters at the start and end of each -alternative branch in the regular expression. -

    -
  • SEE ALSO -

    -pcre(3), Perl 5 documentation -

    -
  • DIAGNOSTICS -

    -Exit status is 0 if any matches were found, 1 if no matches were found, and 2 -for syntax errors or inacessible files (even if matches were found). -

    -
  • AUTHOR -

    -Philip Hazel <ph10@cam.ac.uk> -
    -Copyright (c) 1997-1999 University of Cambridge. diff --git a/srclib/pcre/doc/pgrep.txt b/srclib/pcre/doc/pgrep.txt deleted file mode 100644 index bcd08c0aab..0000000000 --- a/srclib/pcre/doc/pgrep.txt +++ /dev/null @@ -1,86 +0,0 @@ -NAME - pgrep - a grep with Perl-compatible regular expressions. - - - -SYNOPSIS - pgrep [-Vchilnsvx] pattern [file] ... - - - -DESCRIPTION - pgrep searches files for character patterns, in the same way - as other grep commands do, but it uses the PCRE regular - expression library to support patterns that are compatible - with the regular expressions of Perl 5. See pcre(3) for a - full description of syntax and semantics. - - If no files are specified, pgrep reads the standard input. - By default, each line that matches the pattern is copied to - the standard output, and if there is more than one file, the - file name is printed before each line of output. However, - there are options that can change how pgrep behaves. - - Lines are limited to BUFSIZ characters. BUFSIZ is defined in - . The newline character is removed from the end of - each line before it is matched against the pattern. - - - -OPTIONS - -V Write the version number of the PCRE library being - used to the standard error stream. - - -c Do not print individual lines; instead just print - a count of the number of lines that would other- - wise have been printed. If several files are - given, a count is printed for each of them. - - -h Suppress printing of filenames when searching mul- - tiple files. - - -i Ignore upper/lower case distinctions during com- - parisons. - - -l Instead of printing lines from the files, just - print the names of the files containing lines that - would have been printed. Each file name is printed - once, on a separate line. - - -n Precede each line by its line number in the file. - - -s Work silently, that is, display nothing except - error messages. The exit status indicates whether - any matches were found. - - -v Invert the sense of the match, so that lines which - do not match the pattern are now the ones that are - found. - - -x Force the pattern to be anchored (it must start - matching at the beginning of the line) and in - addition, require it to match the entire line. - This is equivalent to having ^ and $ characters at - the start and end of each alternative branch in - the regular expression. - - - -SEE ALSO - pcre(3), Perl 5 documentation - - - - - -DIAGNOSTICS - Exit status is 0 if any matches were found, 1 if no matches - were found, and 2 for syntax errors or inacessible files - (even if matches were found). - - - -AUTHOR - Philip Hazel - Copyright (c) 1997-1999 University of Cambridge. - -- cgit v1.2.3