53 lines
1.4 KiB
Plaintext
53 lines
1.4 KiB
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule PromiseMap
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* @flow
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*/
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'use strict';
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const Deferred = require('./Deferred');
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const invariant = require('./invariant');
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/**
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* A map of asynchronous values that can be get or set in any order. Unlike a
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* normal map, setting the value for a particular key more than once throws.
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* Also unlike a normal map, a key can either be resolved or rejected.
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*/
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class PromiseMap<Tvalue, Treason> {
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_deferred: { [key: string]: Deferred<any, any> };
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constructor() {
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this._deferred = {};
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}
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get(key: string): Promise<any> {
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return getDeferred(this._deferred, key).getPromise();
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}
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resolveKey(key: string, value: Tvalue): void {
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const entry = getDeferred(this._deferred, key);
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invariant(!entry.isSettled(), 'PromiseMap: Already settled `%s`.', key);
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entry.resolve(value);
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}
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rejectKey(key: string, reason: Treason): void {
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const entry = getDeferred(this._deferred, key);
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invariant(!entry.isSettled(), 'PromiseMap: Already settled `%s`.', key);
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entry.reject(reason);
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}
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}
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function getDeferred(entries: { [key: string]: Deferred<any, any> }, key: string): Deferred<any, any> {
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if (!entries.hasOwnProperty(key)) {
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entries[key] = new Deferred();
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}
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return entries[key];
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}
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module.exports = PromiseMap;
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