ui/webui/resources/js/promise_resolver.js

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview PromiseResolver is a helper class that allows creating a
 * Promise that will be fulfilled (resolved or rejected) some time later.
 *
 * Example:
 *  var resolver = new PromiseResolver();
 *  resolver.promise.then(function(result) {
 *    console.log('resolved with', result);
 *  });
 *  ...
 *  ...
 *  resolver.resolve({hello: 'world'});
 */

/**
 * @constructor @struct
 * @template T
 */
function PromiseResolver() {
  /** @private {function(T=): void} */
  this.resolve_;

  /** @private {function(*=): void} */
  this.reject_;

  /** @private {boolean} */
  this.isFulfilled_ = false;

  /** @private {!Promise<T>} */
  this.promise_ = new Promise(function(resolve, reject) {
    this.resolve_ = /** @param {T=} resolution */ function(resolution) {
      resolve(resolution);
      this.isFulfilled_ = true;
    };
    this.reject_ = /** @param {*=} reason */ function(reason) {
      reject(reason);
      this.isFulfilled_ = true;
    };
  }.bind(this));
}

PromiseResolver.prototype = {
  /** @return {boolean} Whether this resolver has been resolved or rejected. */
  get isFulfilled() {
    return this.isFulfilled_;
  },
  set isFulfilled(i) {
    assertNotReached();
  },

  /** @return {!Promise<T>} */
  get promise() {
    return this.promise_;
  },
  set promise(p) {
    assertNotReached();
  },

  /** @return {function(T=): void} */
  get resolve() {
    return this.resolve_;
  },
  set resolve(r) {
    assertNotReached();
  },

  /** @return {function(*=): void} */
  get reject() {
    return this.reject_;
  },
  set reject(s) {
    assertNotReached();
  },
};