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107 lines
3.7 KiB
JavaScript
107 lines
3.7 KiB
JavaScript
"use strict"
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/** @constructor */
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var PromisePolyfill = function(executor) {
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if (!(this instanceof PromisePolyfill)) throw new Error("Promise must be called with `new`")
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if (typeof executor !== "function") throw new TypeError("executor must be a function")
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var self = this, resolvers = [], rejectors = [], resolveCurrent = handler(resolvers, true), rejectCurrent = handler(rejectors, false)
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var instance = self._instance = {resolvers: resolvers, rejectors: rejectors}
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var callAsync = typeof setImmediate === "function" ? setImmediate : setTimeout
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function handler(list, shouldAbsorb) {
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return function execute(value) {
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var then
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try {
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if (shouldAbsorb && value != null && (typeof value === "object" || typeof value === "function") && typeof (then = value.then) === "function") {
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if (value === self) throw new TypeError("Promise can't be resolved w/ itself")
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executeOnce(then.bind(value))
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}
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else {
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callAsync(function() {
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if (!shouldAbsorb && list.length === 0) console.error("Possible unhandled promise rejection:", value)
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for (var i = 0; i < list.length; i++) list[i](value)
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resolvers.length = 0, rejectors.length = 0
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instance.state = shouldAbsorb
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instance.retry = function() {execute(value)}
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})
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}
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}
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catch (e) {
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rejectCurrent(e)
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}
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}
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}
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function executeOnce(then) {
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var runs = 0
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function run(fn) {
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return function(value) {
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if (runs++ > 0) return
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fn(value)
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}
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}
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var onerror = run(rejectCurrent)
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try {then(run(resolveCurrent), onerror)} catch (e) {onerror(e)}
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}
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executeOnce(executor)
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}
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PromisePolyfill.prototype.then = function(onFulfilled, onRejection) {
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var self = this, instance = self._instance
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function handle(callback, list, next, state) {
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list.push(function(value) {
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if (typeof callback !== "function") next(value)
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else try {resolveNext(callback(value))} catch (e) {if (rejectNext) rejectNext(e)}
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})
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if (typeof instance.retry === "function" && state === instance.state) instance.retry()
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}
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var resolveNext, rejectNext
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var promise = new PromisePolyfill(function(resolve, reject) {resolveNext = resolve, rejectNext = reject})
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handle(onFulfilled, instance.resolvers, resolveNext, true), handle(onRejection, instance.rejectors, rejectNext, false)
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return promise
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}
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PromisePolyfill.prototype.catch = function(onRejection) {
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return this.then(null, onRejection)
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}
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PromisePolyfill.resolve = function(value) {
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if (value instanceof PromisePolyfill) return value
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return new PromisePolyfill(function(resolve) {resolve(value)})
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}
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PromisePolyfill.reject = function(value) {
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return new PromisePolyfill(function(resolve, reject) {reject(value)})
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}
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PromisePolyfill.all = function(list) {
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return new PromisePolyfill(function(resolve, reject) {
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var total = list.length, count = 0, values = []
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if (list.length === 0) resolve([])
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else for (var i = 0; i < list.length; i++) {
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(function(i) {
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function consume(value) {
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count++
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values[i] = value
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if (count === total) resolve(values)
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}
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if (list[i] != null && (typeof list[i] === "object" || typeof list[i] === "function") && typeof list[i].then === "function") {
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list[i].then(consume, reject)
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}
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else consume(list[i])
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})(i)
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}
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})
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}
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PromisePolyfill.race = function(list) {
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return new PromisePolyfill(function(resolve, reject) {
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for (var i = 0; i < list.length; i++) {
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list[i].then(resolve, reject)
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}
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})
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}
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if (typeof window !== "undefined") {
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if (typeof window.Promise === "undefined") window.Promise = PromisePolyfill
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module.exports = window.Promise
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} else if (typeof global !== "undefined") {
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if (typeof global.Promise === "undefined") global.Promise = PromisePolyfill
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module.exports = global.Promise
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} else {
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module.exports = PromisePolyfill
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}
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