/**
* @license
* Copyright 2016 Google 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.
*/
goog.provide('shaka.util.PublicPromise');
/**
* A utility to create Promises with convenient public resolve and reject
* methods.
*
* @constructor
* @struct
* @extends {Promise.<T>}
* @return {!Promise.<T>}
* @template T
*/
shaka.util.PublicPromise = function() {
let resolvePromise;
let rejectPromise;
// Promise.call causes an error. It seems that inheriting from a native
// Promise is not permitted by JavaScript interpreters.
// The work-around is to construct a Promise object, modify it to look like
// the compiler's picture of PublicPromise, then return it. The caller of
// new PublicPromise will receive |promise| instead of |this|, and the
// compiler will be aware of the additional properties |resolve| and
// |reject|.
const promise = new Promise(function(resolve, reject) {
resolvePromise = resolve;
rejectPromise = reject;
});
// Now cast the Promise object to our subclass PublicPromise so that the
// compiler will permit us to attach resolve() and reject() to it.
const publicPromise = /** @type {shaka.util.PublicPromise} */(promise);
publicPromise.resolve = resolvePromise;
publicPromise.reject = rejectPromise;
return publicPromise;
};
/** @param {T=} value */
shaka.util.PublicPromise.prototype.resolve = function(value) {};
/** @param {*=} reason */
shaka.util.PublicPromise.prototype.reject = function(reason) {};