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const { ConditionExpressionGroup, ConditionExpression, LOGICAL } = require("./expression");
const { operatorMap } = require("./operators");
/**
* @param {ConditionExpression} expression Expression to evaluate
* @param {object} context Context to evaluate against; These are values for variables in the expression
* @returns {boolean} Whether the expression evaluates true or false
* @throws {Error}
*/
function evaluateExpression(expression, context) {
/**
* @type {import("./operators").ConditionOperator|null}
*/
const operator = operatorMap.get(expression.operator) || null;
if (operator === null) {
throw new Error("Unexpected expression operator ID '" + expression.operator + "'. Expected one of [" + operatorMap.keys().join(",") + "]");
}
if (!Object.prototype.hasOwnProperty.call(context, expression.variable)) {
throw new Error("Variable missing in context: " + expression.variable);
}
return operator.test(context[expression.variable], expression.value);
}
/**
* @param {ConditionExpressionGroup} group Group of expressions to evaluate
* @param {object} context Context to evaluate against; These are values for variables in the expression
* @returns {boolean} Whether the group evaluates true or false
* @throws {Error}
*/
function evaluateExpressionGroup(group, context) {
if (!group.children.length) {
throw new Error("ConditionExpressionGroup must contain at least one child.");
}
let result = null;
for (const child of group.children) {
let childResult;
if (child instanceof ConditionExpression) {
childResult = evaluateExpression(child, context);
} else if (child instanceof ConditionExpressionGroup) {
childResult = evaluateExpressionGroup(child, context);
} else {
throw new Error("Invalid child type in ConditionExpressionGroup. Expected ConditionExpression or ConditionExpressionGroup");
}
if (result === null) {
result = childResult; // Initialize result with the first child's result
} else if (child.andOr === LOGICAL.OR) {
result = result || childResult;
} else if (child.andOr === LOGICAL.AND) {
result = result && childResult;
} else {
throw new Error("Invalid logical operator in child of ConditionExpressionGroup. Expected 'and' or 'or'. Got '" + group.andOr + "'");
}
}
if (result === null) {
throw new Error("ConditionExpressionGroup did not result in a boolean.");
}
return result;
}
module.exports = {
evaluateExpression,
evaluateExpressionGroup,
};
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