memoizeStringOnly.js

/**
 * Copyright 2013-2014 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @providesModule memoizeStringOnly
 * @typechecks static-only
 */

"use strict";

/**
 * Memoizes the return value of a function that accepts one string argument.
 *
 * @param {function} callback
 * @return {function}
 */
function memoizeStringOnly(callback) {
  var cache = {};
  return function(string) {
    if (cache.hasOwnProperty(string)) {
      return cache[string];
    } else {
      return cache[string] = callback.call(this, string);
    }
  };
}

module.exports = memoizeStringOnly;