com.google.javascript.jscomp.js.es6.promise.promise.js Maven / Gradle / Ivy
Show all versions of closure-compiler Show documentation
/*
* Copyright 2016 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'require base';
'require es6/util/makeiterator';
'require util/global';
'require util/polyfill';
/**
* Should we unconditionally override a native Promise implementation with our
* own?
* @define {boolean}
*/
$jscomp.FORCE_POLYFILL_PROMISE = false;
$jscomp.polyfill('Promise',
/**
* @param {*} NativePromise
* @return {*}
* @suppress {reportUnknownTypes}
*/
function(NativePromise) {
// TODO(bradfordcsmith): Do we need to add checks for standards conformance?
// e.g. The version of FireFox we currently use for testing has a Promise
// that fails to reject attempts to fulfill it with itself, but that
// isn't reasonably testable here.
if (NativePromise && !$jscomp.FORCE_POLYFILL_PROMISE) {
return NativePromise;
}
/**
* Schedules code to be executed asynchronously.
* @constructor
* @struct
*/
function AsyncExecutor() {
/**
* Batch of functions to execute.
*
* Will be `null` initially and immediately after a batch finishes
* executing.
* @private {?Array}
*/
this.batch_ = null;
}
/**
* Schedule a function to execute asynchronously.
*
* - The function will execute:
* - After the current call stack has completed executing.
* - After any functions previously scheduled using this object.
* - The return value will be ignored.
* - An exception thrown by the method will be caught and asynchronously
* rethrown when it cannot interrupt any other code. This class provides
* no way to catch such exceptions.
* @param {function():?} f
*/
AsyncExecutor.prototype.asyncExecute = function(f) {
if (this.batch_ == null) {
// no batch created yet, or last batch was fully executed
this.batch_ = [];
var self = this;
this.asyncExecuteFunction(function() { self.executeBatch_(); });
}
this.batch_.push(f);
};
// NOTE: We want to make sure AsyncExecutor will work as expected even if
// testing code should override setTimeout()
/** @const {function(!Function, number)} */
var nativeSetTimeout = $jscomp.global['setTimeout'];
/**
* Schedule a function to execute asynchronously as soon as possible.
*
* NOTE: May be overridden for testing.
* @package
* @param {function()} f
*/
AsyncExecutor.prototype.asyncExecuteFunction = function(f) {
nativeSetTimeout(f, 0);
};
/**
* Execute scheduled jobs in a batch until all are executed or the batch
* execution time limit has been reached.
* @private
*/
AsyncExecutor.prototype.executeBatch_ = function() {
while (this.batch_ && this.batch_.length) {
var /** !Array */ executingBatch = this.batch_;
// Executions scheduled while executing this batch go into a new one to
// avoid the batch array getting too big.
this.batch_ = [];
for (var i = 0; i < executingBatch.length; ++i) {
var f = /** @type {function()} */ (executingBatch[i]);
executingBatch[i] = null; // free memory
try {
f();
} catch (error) {
this.asyncThrow_(error);
}
}
}
// All jobs finished executing, so force scheduling a new batch next
// time asyncExecute() is called.
this.batch_ = null;
};
/**
* @private
* @param {*} exception
*/
AsyncExecutor.prototype.asyncThrow_ = function(exception) {
this.asyncExecuteFunction(function() { throw exception; });
};
/**
* @enum {number}
*/
var PromiseState = {
/** The Promise is waiting for resolution. */
PENDING: 0,
/** The Promise has been resolved with a fulfillment value. */
FULFILLED: 1,
/** The Promise has been resolved with a rejection reason. */
REJECTED: 2
};
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
* @param {function(
* function((TYPE|IThenable|Thenable|null)=),
* function(*=))} executor
* @constructor
* @extends {Promise}
* @template TYPE
*/
var PolyfillPromise = function(executor) {
/** @private {PromiseState} */
this.state_ = PromiseState.PENDING;
/**
* The settled result of the Promise. Immutable once set with either a
* fulfillment value or rejection reason.
* @private {*}
*/
this.result_ = undefined;
/**
* These functions must be asynchronously executed when this promise
* settles.
* @private {?Array}
*/
this.onSettledCallbacks_ = [];
var resolveAndReject = this.createResolveAndReject_();
try {
executor(resolveAndReject.resolve, resolveAndReject.reject);
} catch (e) {
resolveAndReject.reject(e);
}
};
/**
* Create a pair of functions for resolving or rejecting this Promise.
*
* After the resolve or reject function has been called once, later calls
* do nothing.
* @private
* @return {{
* resolve: function((TYPE|IThenable|Thenable|null)=),
* reject: function(*=)
* }}
*/
PolyfillPromise.prototype.createResolveAndReject_ = function() {
var thisPromise = this;
var alreadyCalled = false;
/**
* @param {function(this:PolyfillPromise, T=)} method
* @return {function(T=)}
* @template T
*/
function firstCallWins(method) {
return function(/** T= */ x) {
if (!alreadyCalled) {
alreadyCalled = true;
method.call(thisPromise, x);
}
};
}
return {
resolve: firstCallWins(this.resolveTo_),
reject: firstCallWins(this.reject_)
};
};
/**
* @private
* @param {*=} value
*/
PolyfillPromise.prototype.resolveTo_ = function(value) {
if (value === this) {
this.reject_(new TypeError('A Promise cannot resolve to itself'));
} else if (value instanceof PolyfillPromise) {
this.settleSameAsPromise_(/** @type {!PolyfillPromise} */ (value));
} else if (isObject(value)) {
this.resolveToNonPromiseObj_(/** @type {!Object} */ (value));
} else {
this.fulfill_(value);
}
};
/**
* @private
* @param {!Object} obj
* @suppress {strictMissingProperties} obj.then
*/
PolyfillPromise.prototype.resolveToNonPromiseObj_ = function(obj) {
var thenMethod = undefined;
try {
thenMethod = obj.then;
} catch (error) {
this.reject_(error);
return;
}
if (typeof thenMethod == 'function') {
this.settleSameAsThenable_(thenMethod, /** @type {!Thenable} */ (obj));
} else {
this.fulfill_(obj);
}
};
/**
* @param {*} value anything
* @return {boolean}
*/
function isObject(value) {
switch (typeof value) {
case 'object':
return value != null;
case 'function':
return true;
default:
return false;
}
}
/**
* Reject this promise for the given reason.
* @private
* @param {*=} reason
* @throws {!Error} if this promise is already fulfilled or rejected.
*/
PolyfillPromise.prototype.reject_ = function(reason) {
this.settle_(PromiseState.REJECTED, reason);
};
/**
* Fulfill this promise with the given value.
* @private
* @param {!TYPE} value
* @throws {!Error} when this promise is already fulfilled or rejected.
*/
PolyfillPromise.prototype.fulfill_ = function(value) {
this.settle_(PromiseState.FULFILLED, value);
};
/**
* Fulfill or reject this promise with the given value/reason.
* @private
* @param {!PromiseState} settledState (FULFILLED or REJECTED)
* @param {*} valueOrReason
* @throws {!Error} when this promise is already fulfilled or rejected.
*/
PolyfillPromise.prototype.settle_ = function(settledState, valueOrReason) {
if (this.state_ != PromiseState.PENDING) {
throw new Error(
'Cannot settle(' + settledState + ', ' + valueOrReason +
'): Promise already settled in state' + this.state_);
}
this.state_ = settledState;
this.result_ = valueOrReason;
this.executeOnSettledCallbacks_();
};
PolyfillPromise.prototype.executeOnSettledCallbacks_ = function() {
if (this.onSettledCallbacks_ != null) {
for (var i = 0; i < this.onSettledCallbacks_.length; ++i) {
asyncExecutor.asyncExecute(this.onSettledCallbacks_[i]);
}
this.onSettledCallbacks_ = null; // free memory
}
};
/**
* All promise async execution is managed by a single executor for the
* sake of efficiency.
* @const {!AsyncExecutor}
*/
var asyncExecutor = new AsyncExecutor();
/**
* Arrange to settle this promise in the same way as the given thenable.
* @private
* @param {!PolyfillPromise} promise
*/
PolyfillPromise.prototype.settleSameAsPromise_ = function(promise) {
var methods = this.createResolveAndReject_();
// Calling then() would create an unnecessary extra promise.
promise.callWhenSettled_(methods.resolve, methods.reject);
};
/**
* Arrange to settle this promise in the same way as the given thenable.
* @private
* @param {function(
* function((TYPE|IThenable|Thenable|null)=),
* function(*=))
* } thenMethod
* @param {!Thenable} thenable
*/
PolyfillPromise.prototype.settleSameAsThenable_ = function(
thenMethod, thenable) {
var methods = this.createResolveAndReject_();
// Don't trust an unknown thenable implementation not to throw exceptions.
try {
thenMethod.call(thenable, methods.resolve, methods.reject);
} catch (error) {
methods.reject(error);
}
};
/** @override */
PolyfillPromise.prototype.then = function(onFulfilled, onRejected) {
var resolveChild;
var rejectChild;
var childPromise = new PolyfillPromise(function(resolve, reject) {
resolveChild = resolve;
rejectChild = reject;
});
function createCallback(paramF, defaultF) {
// The spec says to ignore non-function values for onFulfilled and
// onRejected
if (typeof paramF == 'function') {
return function(x) {
try {
resolveChild(paramF(x));
} catch (error) {
rejectChild(error);
}
};
} else {
return defaultF;
}
}
this.callWhenSettled_(
createCallback(onFulfilled, resolveChild),
createCallback(onRejected, rejectChild));
return childPromise;
};
/** @override */
PolyfillPromise.prototype.catch = function(onRejected) {
return this.then(undefined, onRejected);
};
PolyfillPromise.prototype.callWhenSettled_ = function(
onFulfilled, onRejected) {
var /** !PolyfillPromise */ thisPromise = this;
function callback() {
switch (thisPromise.state_) {
case PromiseState.FULFILLED:
onFulfilled(thisPromise.result_);
break;
case PromiseState.REJECTED:
onRejected(thisPromise.result_);
break;
default:
throw new Error('Unexpected state: ' + thisPromise.state_);
}
}
if (this.onSettledCallbacks_ == null) {
// we've already settled
asyncExecutor.asyncExecute(callback);
} else {
this.onSettledCallbacks_.push(callback);
}
};
// called locally, so give it a name
function resolvingPromise(opt_value) {
if (opt_value instanceof PolyfillPromise) {
return opt_value;
} else {
return new PolyfillPromise(function(resolve, reject) {
resolve(opt_value);
});
}
}
PolyfillPromise['resolve'] = resolvingPromise;
PolyfillPromise['reject'] = function(opt_reason) {
return new PolyfillPromise(function(resolve, reject) {
reject(opt_reason);
});
};
PolyfillPromise['race'] = function(thenablesOrValues) {
return new PolyfillPromise(function(resolve, reject) {
var /** !Iterator<*> */ iterator =
$jscomp.makeIterator(thenablesOrValues);
for (var /** !IIterableResult<*> */ iterRec = iterator.next();
!iterRec.done;
iterRec = iterator.next()) {
// Using resolvingPromise() allows us to treat all elements the same
// way.
// NOTE: resolvingPromise(promise) always returns the argument
// unchanged.
// Using .callWhenSettled_() instead of .then() avoids creating an
// unnecessary extra promise.
resolvingPromise(iterRec.value).callWhenSettled_(resolve, reject);
}
});
};
PolyfillPromise['all'] = function(thenablesOrValues) {
var /** !Iterator<*> */ iterator = $jscomp.makeIterator(thenablesOrValues);
var /** !IIterableResult<*> */ iterRec = iterator.next();
if (iterRec.done) {
return resolvingPromise([]);
} else {
return new PolyfillPromise(function(resolveAll, rejectAll) {
var resultsArray = [];
var unresolvedCount = 0;
function onFulfilled(i) {
return function(ithResult) {
resultsArray[i] = ithResult;
unresolvedCount--;
if (unresolvedCount == 0) {
resolveAll(resultsArray);
}
};
}
do {
resultsArray.push(undefined);
unresolvedCount++;
// Using resolvingPromise() allows us to treat all elements the same
// way.
// NOTE: resolvingPromise(promise) always returns the argument
// unchanged. Using .callWhenSettled_() instead of .then() avoids
// creating an unnecessary extra promise.
resolvingPromise(iterRec.value)
.callWhenSettled_(
onFulfilled(resultsArray.length - 1), rejectAll);
iterRec = iterator.next();
} while (!iterRec.done);
});
}
};
return PolyfillPromise;
}, 'es6', 'es3');