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'use strict';
var PENDING = 'pending';
var SETTLED = 'settled';
var FULFILLED = 'fulfilled';
var REJECTED = 'rejected';
var NOOP = function () {};
var isNode = typeof global !== 'undefined' && typeof global.process !== 'undefined' && typeof global.process.emit === 'function';
var asyncSetTimer = typeof setImmediate === 'undefined' ? setTimeout : setImmediate;
var asyncQueue = [];
var asyncTimer;
function asyncFlush() {
// run promise callbacks
for (var i = 0; i < asyncQueue.length; i++) {
asyncQueue[i][0](asyncQueue[i][1]);
}
// reset async asyncQueue
asyncQueue = [];
asyncTimer = false;
}
function asyncCall(callback, arg) {
asyncQueue.push([callback, arg]);
if (!asyncTimer) {
asyncTimer = true;
asyncSetTimer(asyncFlush, 0);
}
}
function invokeResolver(resolver, promise) {
function resolvePromise(value) {
resolve(promise, value);
}
function rejectPromise(reason) {
reject(promise, reason);
}
try {
resolver(resolvePromise, rejectPromise);
} catch (e) {
rejectPromise(e);
}
}
function invokeCallback(subscriber) {
var owner = subscriber.owner;
var settled = owner._state;
var value = owner._data;
var callback = subscriber[settled];
var promise = subscriber.then;
if (typeof callback === 'function') {
settled = FULFILLED;
try {
value = callback(value);
} catch (e) {
reject(promise, e);
}
}
if (!handleThenable(promise, value)) {
if (settled === FULFILLED) {
resolve(promise, value);
}
if (settled === REJECTED) {
reject(promise, value);
}
}
}
function handleThenable(promise, value) {
var resolved;
try {
if (promise === value) {
throw new TypeError('A promises callback cannot return that same promise.');
}
if (value && (typeof value === 'function' || typeof value === 'object')) {
// then should be retrieved only once
var then = value.then;
if (typeof then === 'function') {
then.call(value, function (val) {
if (!resolved) {
resolved = true;
if (value === val) {
fulfill(promise, val);
} else {
resolve(promise, val);
}
}
}, function (reason) {
if (!resolved) {
resolved = true;
reject(promise, reason);
}
});
return true;
}
}
} catch (e) {
if (!resolved) {
reject(promise, e);
}
return true;
}
return false;
}
function resolve(promise, value) {
if (promise === value || !handleThenable(promise, value)) {
fulfill(promise, value);
}
}
function fulfill(promise, value) {
if (promise._state === PENDING) {
promise._state = SETTLED;
promise._data = value;
asyncCall(publishFulfillment, promise);
}
}
function reject(promise, reason) {
if (promise._state === PENDING) {
promise._state = SETTLED;
promise._data = reason;
asyncCall(publishRejection, promise);
}
}
function publish(promise) {
promise._then = promise._then.forEach(invokeCallback);
}
function publishFulfillment(promise) {
promise._state = FULFILLED;
publish(promise);
}
function publishRejection(promise) {
promise._state = REJECTED;
publish(promise);
if (!promise._handled && isNode) {
global.process.emit('unhandledRejection', promise._data, promise);
}
}
function notifyRejectionHandled(promise) {
global.process.emit('rejectionHandled', promise);
}
/**
* @class
*/
function Promise(resolver) {
if (typeof resolver !== 'function') {
throw new TypeError('Promise resolver ' + resolver + ' is not a function');
}
if (this instanceof Promise === false) {
throw new TypeError('Failed to construct \'Promise\': Please use the \'new\' operator, this object constructor cannot be called as a function.');
}
this._then = [];
invokeResolver(resolver, this);
}
Promise.prototype = {
constructor: Promise,
_state: PENDING,
_then: null,
_data: undefined,
_handled: false,
then: function (onFulfillment, onRejection) {
var subscriber = {
owner: this,
then: new this.constructor(NOOP),
fulfilled: onFulfillment,
rejected: onRejection
};
if ((onRejection || onFulfillment) && !this._handled) {
this._handled = true;
if (this._state === REJECTED && isNode) {
asyncCall(notifyRejectionHandled, this);
}
}
if (this._state === FULFILLED || this._state === REJECTED) {
// already resolved, call callback async
asyncCall(invokeCallback, subscriber);
} else {
// subscribe
this._then.push(subscriber);
}
return subscriber.then;
},
catch: function (onRejection) {
return this.then(null, onRejection);
}
};
Promise.all = function (promises) {
if (!Array.isArray(promises)) {
throw new TypeError('You must pass an array to Promise.all().');
}
return new Promise(function (resolve, reject) {
var results = [];
var remaining = 0;
function resolver(index) {
remaining++;
return function (value) {
results[index] = value;
if (!--remaining) {
resolve(results);
}
};
}
for (var i = 0, promise; i < promises.length; i++) {
promise = promises[i];
if (promise && typeof promise.then === 'function') {
promise.then(resolver(i), reject);
} else {
results[i] = promise;
}
}
if (!remaining) {
resolve(results);
}
});
};
Promise.race = function (promises) {
if (!Array.isArray(promises)) {
throw new TypeError('You must pass an array to Promise.race().');
}
return new Promise(function (resolve, reject) {
for (var i = 0, promise; i < promises.length; i++) {
promise = promises[i];
if (promise && typeof promise.then === 'function') {
promise.then(resolve, reject);
} else {
resolve(promise);
}
}
});
};
Promise.resolve = function (value) {
if (value && typeof value === 'object' && value.constructor === Promise) {
return value;
}
return new Promise(function (resolve) {
resolve(value);
});
};
Promise.reject = function (reason) {
return new Promise(function (resolve, reject) {
reject(reason);
});
};
module.exports = Promise;