Source: lib/util/public_promise.js

  1. /**
  2.  * @license
  3.  * Copyright 2016 Google Inc.
  4.  *
  5.  * Licensed under the Apache License, Version 2.0 (the "License");
  6.  * you may not use this file except in compliance with the License.
  7.  * You may obtain a copy of the License at
  8.  *
  9.  *     http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  18. goog.provide('shaka.util.PublicPromise');
  21. /**
  22.  * A utility to create Promises with convenient public resolve and reject
  23.  * methods.
  24.  *
  25.  * @constructor
  26.  * @struct
  27.  * @extends {Promise.<T>}
  28.  * @return {Promise.<T>}
  29.  * @template T
  30.  */
  31. shaka.util.PublicPromise = function() {
  32.   let resolvePromise;
  33.   let rejectPromise;
  35.   // Promise.call causes an error.  It seems that inheriting from a native
  36.   // Promise is not permitted by JavaScript interpreters.
  38.   // The work-around is to construct a Promise object, modify it to look like
  39.   // the compiler's picture of PublicPromise, then return it.  The caller of
  40.   // new PublicPromise will receive |promise| instead of |this|, and the
  41.   // compiler will be aware of the additional properties |resolve| and
  42.   // |reject|.
  44.   let promise = new Promise(function(resolve, reject) {
  45.     resolvePromise = resolve;
  46.     rejectPromise = reject;
  47.   });
  49.   promise.resolve = resolvePromise;
  50.   promise.reject = rejectPromise;
  52.   return promise;
  53. };
  56. /** @param {T=} value */
  57. shaka.util.PublicPromise.prototype.resolve = function(value) {};
  60. /** @param {*=} reason */
  61. shaka.util.PublicPromise.prototype.reject = function(reason) {};