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promise.js
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promise.js
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'use strict';
//This file contains then/promise specific extensions to the core promise API
var Promise = require('./core.js')
var asap = require('asap')
module.exports = Promise
/* Static Functions */
function ValuePromise(value) {
this.then = function (onFulfilled) {
if (typeof onFulfilled !== 'function') return this
return new Promise(function (resolve, reject) {
asap(function () {
try {
resolve(onFulfilled(value))
} catch (ex) {
reject(ex);
}
})
})
}
}
ValuePromise.prototype = Promise.prototype
var TRUE = new ValuePromise(true)
var FALSE = new ValuePromise(false)
var NULL = new ValuePromise(null)
var UNDEFINED = new ValuePromise(undefined)
var ZERO = new ValuePromise(0)
var EMPTYSTRING = new ValuePromise('')
Promise.resolve = function (value) {
if (value instanceof Promise) return value
if (value === null) return NULL
if (value === undefined) return UNDEFINED
if (value === true) return TRUE
if (value === false) return FALSE
if (value === 0) return ZERO
if (value === '') return EMPTYSTRING
if (typeof value === 'object' || typeof value === 'function') {
try {
var then = value.then
if (typeof then === 'function') {
return new Promise(then.bind(value))
}
} catch (ex) {
return new Promise(function (resolve, reject) {
reject(ex)
})
}
}
return new ValuePromise(value)
}
Promise.from = Promise.cast = function (value) {
var err = new Error('Promise.from and Promise.cast are deprecated, use Promise.resolve instead')
err.name = 'Warning'
console.warn(err.stack)
return Promise.resolve(value)
}
Promise.denodeify = function (fn, argumentCount) {
argumentCount = argumentCount || Infinity
return function () {
var self = this
var args = Array.prototype.slice.call(arguments)
return new Promise(function (resolve, reject) {
while (args.length && args.length > argumentCount) {
args.pop()
}
args.push(function (err, res) {
if (err) reject(err)
else resolve(res)
})
fn.apply(self, args)
})
}
}
Promise.nodeify = function (fn) {
return function () {
var args = Array.prototype.slice.call(arguments)
var callback = typeof args[args.length - 1] === 'function' ? args.pop() : null
try {
return fn.apply(this, arguments).nodeify(callback)
} catch (ex) {
if (callback === null || typeof callback == 'undefined') {
return new Promise(function (resolve, reject) { reject(ex) })
} else {
asap(function () {
callback(ex)
})
}
}
}
}
Promise.all = function () {
var calledWithArray = arguments.length === 1 && Array.isArray(arguments[0])
var args = Array.prototype.slice.call(calledWithArray ? arguments[0] : arguments)
if (!calledWithArray) {
var err = new Error('Promise.all should be called with a single array, calling it with multiple arguments is deprecated')
err.name = 'Warning'
console.warn(err.stack)
}
return new Promise(function (resolve, reject) {
if (args.length === 0) return resolve([])
var remaining = args.length
function res(i, val) {
try {
if (val && (typeof val === 'object' || typeof val === 'function')) {
var then = val.then
if (typeof then === 'function') {
then.call(val, function (val) { res(i, val) }, reject)
return
}
}
args[i] = val
if (--remaining === 0) {
resolve(args);
}
} catch (ex) {
reject(ex)
}
}
for (var i = 0; i < args.length; i++) {
res(i, args[i])
}
})
}
Promise.reject = function (value) {
return new Promise(function (resolve, reject) {
reject(value);
});
}
Promise.race = function (values) {
return new Promise(function (resolve, reject) {
values.forEach(function(value){
Promise.resolve(value).then(resolve, reject);
})
});
}
/* Prototype Methods */
Promise.prototype.done = function (onFulfilled, onRejected) {
var self = arguments.length ? this.then.apply(this, arguments) : this
self.then(null, function (err) {
asap(function () {
throw err
})
})
}
Promise.prototype.nodeify = function (callback) {
if (typeof callback != 'function') return this
this.then(function (value) {
asap(function () {
callback(null, value)
})
}, function (err) {
asap(function () {
callback(err)
})
})
}
Promise.prototype['catch'] = function (onRejected) {
return this.then(null, onRejected);
}