notes/node_modules/regex-cache/index.js

/*!
 * regex-cache <https://github.com/jonschlinkert/regex-cache>
 *
 * Copyright (c) 2015 Jon Schlinkert.
 * Licensed under the MIT license.
 */

'use strict';

var isPrimitive = require('is-primitive');
var equal = require('is-equal-shallow');
var basic = {};
var cache = {};

/**
 * Expose `regexCache`
 */

module.exports = regexCache;

/**
 * Memoize the results of a call to the new RegExp constructor.
 *
 * @param  {Function} fn [description]
 * @param  {String} str [description]
 * @param  {Options} options [description]
 * @param  {Boolean} nocompare [description]
 * @return {RegExp}
 */

function regexCache(fn, str, opts) {
  var key = '_default_', regex, cached;

  if (!str && !opts) {
    if (typeof fn !== 'function') {
      return fn;
    }
    return basic[key] || (basic[key] = fn(str));
  }

  var isString = typeof str === 'string';
  if (isString) {
    if (!opts) {
      return basic[str] || (basic[str] = fn(str));
    }
    key = str;
  } else {
    opts = str;
  }

  cached = cache[key];
  if (cached && equal(cached.opts, opts)) {
    return cached.regex;
  }

  memo(key, opts, (regex = fn(str, opts)));
  return regex;
}

function memo(key, opts, regex) {
  cache[key] = {regex: regex, opts: opts};
}

/**
 * Expose `cache`
 */

module.exports.cache = cache;
module.exports.basic = basic;