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'use strict';
var define = require('define-property');
var extend = require('extend-shallow');
var not = require('regex-not');
var MAX_LENGTH = 1024 * 64;
/**
* Session cache
*/
var cache = {};
/**
* Create a regular expression from the given `pattern` string.
*
* @param {String|RegExp} `pattern` Pattern can be a string or regular expression.
* @param {Object} `options`
* @return {RegExp}
* @api public
*/
module.exports = function(patterns, options) {
if (!Array.isArray(patterns)) {
return makeRe(patterns, options);
}
return makeRe(patterns.join('|'), options);
};
/**
* Create a regular expression from the given `pattern` string.
*
* @param {String|RegExp} `pattern` Pattern can be a string or regular expression.
* @param {Object} `options`
* @return {RegExp}
* @api public
*/
function makeRe(pattern, options) {
if (pattern instanceof RegExp) {
return pattern;
}
if (typeof pattern !== 'string') {
throw new TypeError('expected a string');
}
if (pattern.length > MAX_LENGTH) {
throw new Error('expected pattern to be less than ' + MAX_LENGTH + ' characters');
}
var key = pattern;
// do this before shallow cloning options, it's a lot faster
if (!options || (options && options.cache !== false)) {
key = createKey(pattern, options);
if (cache.hasOwnProperty(key)) {
return cache[key];
}
}
var opts = extend({}, options);
if (opts.contains === true) {
if (opts.negate === true) {
opts.strictNegate = false;
} else {
opts.strict = false;
}
}
if (opts.strict === false) {
opts.strictOpen = false;
opts.strictClose = false;
}
var open = opts.strictOpen !== false ? '^' : '';
var close = opts.strictClose !== false ? '$' : '';
var flags = opts.flags || '';
var regex;
if (opts.nocase === true && !/i/.test(flags)) {
flags += 'i';
}
try {
if (opts.negate || typeof opts.strictNegate === 'boolean') {
pattern = not.create(pattern, opts);
}
var str = open + '(?:' + pattern + ')' + close;
regex = new RegExp(str, flags);
} catch (err) {
if (opts.strictErrors === true) {
err.key = key;
err.pattern = pattern;
err.originalOptions = options;
err.createdOptions = opts;
throw err;
}
try {
regex = new RegExp('^' + pattern.replace(/(\W)/g, '\\$1') + '$');
} catch (err) {
regex = /.^/; //<= match nothing
}
}
if (opts.cache !== false) {
cacheRegex(regex, key, pattern, opts);
}
return regex;
}
/**
* Cache generated regex. This can result in dramatic speed improvements
* and simplify debugging by adding options and pattern to the regex. It can be
* disabled by passing setting `options.cache` to false.
*/
function cacheRegex(regex, key, pattern, options) {
define(regex, 'cached', true);
define(regex, 'pattern', pattern);
define(regex, 'options', options);
define(regex, 'key', key);
cache[key] = regex;
}
/**
* Create the key to use for memoization. The key is generated
* by iterating over the options and concatenating key-value pairs
* to the pattern string.
*/
function createKey(pattern, options) {
if (!options) return pattern;
var key = pattern;
for (var prop in options) {
if (options.hasOwnProperty(prop)) {
key += ';' + prop + '=' + String(options[prop]);
}
}
return key;
}
/**
* Expose `makeRe`
*/
module.exports.makeRe = makeRe;
|
