299 lines
6.8 KiB
JavaScript
299 lines
6.8 KiB
JavaScript
'use strict';
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var immediate = require('immediate');
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/* istanbul ignore next */
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function INTERNAL() {}
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var handlers = {};
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var REJECTED = ['REJECTED'];
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var FULFILLED = ['FULFILLED'];
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var PENDING = ['PENDING'];
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/* istanbul ignore else */
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if (!process.browser) {
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// in which we actually take advantage of JS scoping
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var UNHANDLED = ['UNHANDLED'];
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}
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module.exports = Promise;
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function Promise(resolver) {
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if (typeof resolver !== 'function') {
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throw new TypeError('resolver must be a function');
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}
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this.state = PENDING;
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this.queue = [];
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this.outcome = void 0;
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/* istanbul ignore else */
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if (!process.browser) {
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this.handled = UNHANDLED;
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}
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if (resolver !== INTERNAL) {
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safelyResolveThenable(this, resolver);
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}
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}
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Promise.prototype.finally = function (callback) {
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if (typeof callback !== 'function') {
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return this;
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}
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var p = this.constructor;
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return this.then(resolve, reject);
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function resolve(value) {
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function yes () {
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return value;
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}
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return p.resolve(callback()).then(yes);
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}
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function reject(reason) {
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function no () {
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throw reason;
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}
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return p.resolve(callback()).then(no);
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}
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};
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Promise.prototype.catch = function (onRejected) {
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return this.then(null, onRejected);
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};
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Promise.prototype.then = function (onFulfilled, onRejected) {
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if (typeof onFulfilled !== 'function' && this.state === FULFILLED ||
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typeof onRejected !== 'function' && this.state === REJECTED) {
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return this;
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}
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var promise = new this.constructor(INTERNAL);
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/* istanbul ignore else */
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if (!process.browser) {
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if (this.handled === UNHANDLED) {
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this.handled = null;
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}
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}
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if (this.state !== PENDING) {
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var resolver = this.state === FULFILLED ? onFulfilled : onRejected;
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unwrap(promise, resolver, this.outcome);
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} else {
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this.queue.push(new QueueItem(promise, onFulfilled, onRejected));
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}
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return promise;
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};
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function QueueItem(promise, onFulfilled, onRejected) {
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this.promise = promise;
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if (typeof onFulfilled === 'function') {
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this.onFulfilled = onFulfilled;
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this.callFulfilled = this.otherCallFulfilled;
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}
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if (typeof onRejected === 'function') {
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this.onRejected = onRejected;
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this.callRejected = this.otherCallRejected;
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}
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}
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QueueItem.prototype.callFulfilled = function (value) {
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handlers.resolve(this.promise, value);
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};
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QueueItem.prototype.otherCallFulfilled = function (value) {
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unwrap(this.promise, this.onFulfilled, value);
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};
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QueueItem.prototype.callRejected = function (value) {
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handlers.reject(this.promise, value);
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};
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QueueItem.prototype.otherCallRejected = function (value) {
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unwrap(this.promise, this.onRejected, value);
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};
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function unwrap(promise, func, value) {
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immediate(function () {
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var returnValue;
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try {
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returnValue = func(value);
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} catch (e) {
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return handlers.reject(promise, e);
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}
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if (returnValue === promise) {
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handlers.reject(promise, new TypeError('Cannot resolve promise with itself'));
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} else {
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handlers.resolve(promise, returnValue);
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}
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});
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}
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handlers.resolve = function (self, value) {
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var result = tryCatch(getThen, value);
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if (result.status === 'error') {
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return handlers.reject(self, result.value);
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}
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var thenable = result.value;
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if (thenable) {
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safelyResolveThenable(self, thenable);
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} else {
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self.state = FULFILLED;
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self.outcome = value;
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var i = -1;
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var len = self.queue.length;
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while (++i < len) {
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self.queue[i].callFulfilled(value);
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}
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}
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return self;
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};
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handlers.reject = function (self, error) {
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self.state = REJECTED;
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self.outcome = error;
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/* istanbul ignore else */
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if (!process.browser) {
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if (self.handled === UNHANDLED) {
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immediate(function () {
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if (self.handled === UNHANDLED) {
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process.emit('unhandledRejection', error, self);
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}
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});
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}
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}
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var i = -1;
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var len = self.queue.length;
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while (++i < len) {
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self.queue[i].callRejected(error);
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}
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return self;
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};
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function getThen(obj) {
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// Make sure we only access the accessor once as required by the spec
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var then = obj && obj.then;
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if (obj && (typeof obj === 'object' || typeof obj === 'function') && typeof then === 'function') {
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return function appyThen() {
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then.apply(obj, arguments);
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};
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}
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}
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function safelyResolveThenable(self, thenable) {
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// Either fulfill, reject or reject with error
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var called = false;
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function onError(value) {
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if (called) {
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return;
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}
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called = true;
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handlers.reject(self, value);
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}
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function onSuccess(value) {
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if (called) {
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return;
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}
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called = true;
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handlers.resolve(self, value);
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}
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function tryToUnwrap() {
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thenable(onSuccess, onError);
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}
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var result = tryCatch(tryToUnwrap);
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if (result.status === 'error') {
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onError(result.value);
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}
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}
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function tryCatch(func, value) {
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var out = {};
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try {
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out.value = func(value);
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out.status = 'success';
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} catch (e) {
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out.status = 'error';
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out.value = e;
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}
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return out;
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}
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Promise.resolve = resolve;
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function resolve(value) {
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if (value instanceof this) {
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return value;
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}
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return handlers.resolve(new this(INTERNAL), value);
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}
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Promise.reject = reject;
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function reject(reason) {
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var promise = new this(INTERNAL);
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return handlers.reject(promise, reason);
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}
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Promise.all = all;
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function all(iterable) {
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var self = this;
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if (Object.prototype.toString.call(iterable) !== '[object Array]') {
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return this.reject(new TypeError('must be an array'));
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}
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var len = iterable.length;
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var called = false;
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if (!len) {
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return this.resolve([]);
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}
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var values = new Array(len);
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var resolved = 0;
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var i = -1;
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var promise = new this(INTERNAL);
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while (++i < len) {
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allResolver(iterable[i], i);
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}
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return promise;
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function allResolver(value, i) {
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self.resolve(value).then(resolveFromAll, function (error) {
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if (!called) {
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called = true;
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handlers.reject(promise, error);
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}
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});
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function resolveFromAll(outValue) {
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values[i] = outValue;
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if (++resolved === len && !called) {
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called = true;
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handlers.resolve(promise, values);
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}
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}
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}
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}
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Promise.race = race;
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function race(iterable) {
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var self = this;
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if (Object.prototype.toString.call(iterable) !== '[object Array]') {
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return this.reject(new TypeError('must be an array'));
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}
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var len = iterable.length;
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var called = false;
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if (!len) {
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return this.resolve([]);
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}
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var i = -1;
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var promise = new this(INTERNAL);
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while (++i < len) {
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resolver(iterable[i]);
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}
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return promise;
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function resolver(value) {
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self.resolve(value).then(function (response) {
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if (!called) {
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called = true;
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handlers.resolve(promise, response);
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}
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}, function (error) {
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if (!called) {
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called = true;
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handlers.reject(promise, error);
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}
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});
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}
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}
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