diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/rbtree.c | 98 |
1 files changed, 64 insertions, 34 deletions
diff --git a/lib/rbtree.c b/lib/rbtree.c index 80b092538fa9..938061ecbe61 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -47,9 +47,14 @@ #define RB_RED 0 #define RB_BLACK 1 -#define rb_color(r) ((r)->__rb_parent_color & 1) -#define rb_is_red(r) (!rb_color(r)) -#define rb_is_black(r) rb_color(r) +#define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) + +#define __rb_color(pc) ((pc) & 1) +#define __rb_is_black(pc) __rb_color(pc) +#define __rb_is_red(pc) (!__rb_color(pc)) +#define rb_color(rb) __rb_color((rb)->__rb_parent_color) +#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) +#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) static inline void rb_set_black(struct rb_node *rb) { @@ -378,6 +383,7 @@ void rb_erase(struct rb_node *node, struct rb_root *root) { struct rb_node *child = node->rb_right, *tmp = node->rb_left; struct rb_node *parent, *rebalance; + unsigned long pc; if (!tmp) { /* @@ -387,51 +393,75 @@ void rb_erase(struct rb_node *node, struct rb_root *root) * and node must be black due to 4). We adjust colors locally * so as to bypass __rb_erase_color() later on. */ - - parent = rb_parent(node); + pc = node->__rb_parent_color; + parent = __rb_parent(pc); __rb_change_child(node, child, parent, root); if (child) { - rb_set_parent_color(child, parent, RB_BLACK); + child->__rb_parent_color = pc; rebalance = NULL; - } else { - rebalance = rb_is_black(node) ? parent : NULL; - } + } else + rebalance = __rb_is_black(pc) ? parent : NULL; } else if (!child) { /* Still case 1, but this time the child is node->rb_left */ - parent = rb_parent(node); + tmp->__rb_parent_color = pc = node->__rb_parent_color; + parent = __rb_parent(pc); __rb_change_child(node, tmp, parent, root); - rb_set_parent_color(tmp, parent, RB_BLACK); rebalance = NULL; } else { - struct rb_node *old = node, *left; - - node = child; - while ((left = node->rb_left) != NULL) - node = left; - - __rb_change_child(old, node, rb_parent(old), root); - - child = node->rb_right; - parent = rb_parent(node); - - if (parent == old) { - parent = node; + struct rb_node *successor = child, *child2; + tmp = child->rb_left; + if (!tmp) { + /* + * Case 2: node's successor is its right child + * + * (n) (s) + * / \ / \ + * (x) (s) -> (x) (c) + * \ + * (c) + */ + parent = child; + child2 = child->rb_right; } else { - parent->rb_left = child; - - node->rb_right = old->rb_right; - rb_set_parent(old->rb_right, node); + /* + * Case 3: node's successor is leftmost under + * node's right child subtree + * + * (n) (s) + * / \ / \ + * (x) (y) -> (x) (y) + * / / + * (p) (p) + * / / + * (s) (c) + * \ + * (c) + */ + do { + parent = successor; + successor = tmp; + tmp = tmp->rb_left; + } while (tmp); + parent->rb_left = child2 = successor->rb_right; + successor->rb_right = child; + rb_set_parent(child, successor); } - if (child) { - rb_set_parent_color(child, parent, RB_BLACK); + successor->rb_left = tmp = node->rb_left; + rb_set_parent(tmp, successor); + + pc = node->__rb_parent_color; + tmp = __rb_parent(pc); + __rb_change_child(node, successor, tmp, root); + if (child2) { + successor->__rb_parent_color = pc; + rb_set_parent_color(child2, parent, RB_BLACK); rebalance = NULL; } else { - rebalance = rb_is_black(node) ? parent : NULL; + unsigned long pc2 = successor->__rb_parent_color; + successor->__rb_parent_color = pc; + rebalance = __rb_is_black(pc2) ? parent : NULL; } - node->__rb_parent_color = old->__rb_parent_color; - node->rb_left = old->rb_left; - rb_set_parent(old->rb_left, node); } if (rebalance) |