75 lines
2.0 KiB
Plaintext
75 lines
2.0 KiB
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule Deferred
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* @typechecks
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* @flow
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*/
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/**
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* Deferred provides a Promise-like API that exposes methods to resolve and
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* reject the Promise. It is most useful when converting non-Promise code to use
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* Promises.
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*
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* If you want to export the Promise without exposing access to the resolve and
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* reject methods, you should export `getPromise` which returns a Promise with
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* the same semantics excluding those methods.
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*/
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class Deferred<Tvalue, Treason> {
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_settled: boolean;
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_promise: Promise<any>;
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_resolve: (value: Tvalue) => void;
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_reject: (reason: Treason) => void;
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constructor() {
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this._settled = false;
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this._promise = new Promise((resolve, reject) => {
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this._resolve = (resolve: any);
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this._reject = (reject: any);
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});
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}
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getPromise(): Promise<any> {
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return this._promise;
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}
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resolve(value: Tvalue): void {
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this._settled = true;
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this._resolve(value);
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}
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reject(reason: Treason): void {
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this._settled = true;
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this._reject(reason);
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}
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catch(): Promise<any> {
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return Promise.prototype.catch.apply(this._promise, arguments);
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}
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then(): Promise<any> {
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return Promise.prototype.then.apply(this._promise, arguments);
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}
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done(): void {
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// Embed the polyfill for the non-standard Promise.prototype.done so that
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// users of the open source fbjs don't need a custom lib for Promise
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const promise = arguments.length ? this._promise.then.apply(this._promise, arguments) : this._promise;
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promise.then(undefined, function (err) {
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setTimeout(function () {
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throw err;
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}, 0);
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});
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}
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isSettled(): boolean {
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return this._settled;
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}
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}
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module.exports = Deferred;
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