Source/JavaScriptCore/builtins/PromiseOperations.js

/*
 * Copyright (C) 2015 Yusuke Suzuki <utatane.tea@gmail.com>.
 * Copyright (C) 2016 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// @internal

@globalPrivate
function isPromise(promise)
{
    "use strict";

    return @isObject(promise) && !!@getByIdDirectPrivate(promise, "promiseState");
}

@globalPrivate
function newPromiseReaction(capability, onFulfilled, onRejected)
{
    "use strict";

    return {
        @capabilities: capability,
        @onFulfilled: onFulfilled,
        @onRejected: onRejected,
    };
}

@globalPrivate
function newPromiseCapability(constructor)
{
    "use strict";

    if (!@isConstructor(constructor))
        @throwTypeError("promise capability requires a constructor function");

    var promiseCapability = {
        @promise: @undefined,
        @resolve: @undefined,
        @reject: @undefined
    };

    function @executor(resolve, reject)
    {
        if (promiseCapability.@resolve !== @undefined)
            @throwTypeError("resolve function is already set");
        if (promiseCapability.@reject !== @undefined)
            @throwTypeError("reject function is already set");

        promiseCapability.@resolve = resolve;
        promiseCapability.@reject = reject;
    }

    var promise = new constructor(@executor);

    if (typeof promiseCapability.@resolve !== "function")
        @throwTypeError("executor did not take a resolve function");

    if (typeof promiseCapability.@reject !== "function")
        @throwTypeError("executor did not take a reject function");

    promiseCapability.@promise = promise;

    return promiseCapability;
}

@globalPrivate
function newHandledRejectedPromise(error)
{
    "use strict";
    let promise = @Promise.@reject(error);
    @putByIdDirectPrivate(promise, "promiseIsHandled", true);
    return promise;
}

@globalPrivate
function triggerPromiseReactions(state, reactions, argument)
{
    "use strict";

    for (var index = 0, length = reactions.length; index < length; ++index)
        @enqueueJob(@promiseReactionJob, [state, reactions[index], argument]);
}

@globalPrivate
function rejectPromise(promise, reason)
{
    "use strict";

    var reactions = @getByIdDirectPrivate(promise, "promiseReactions");
    @putByIdDirectPrivate(promise, "promiseResult", reason);
    @putByIdDirectPrivate(promise, "promiseReactions", @undefined);
    @putByIdDirectPrivate(promise, "promiseState", @promiseStateRejected);

    @InspectorInstrumentation.promiseRejected(promise, reason, reactions);

    if (!@getByIdDirectPrivate(promise, "promiseIsHandled"))
        @hostPromiseRejectionTracker(promise, @promiseRejectionReject);

    @triggerPromiseReactions(@promiseStateRejected, reactions, reason);
}

@globalPrivate
function fulfillPromise(promise, value)
{
    "use strict";

    var reactions = @getByIdDirectPrivate(promise, "promiseReactions");
    @putByIdDirectPrivate(promise, "promiseResult", value);
    @putByIdDirectPrivate(promise, "promiseReactions", @undefined);
    @putByIdDirectPrivate(promise, "promiseState", @promiseStateFulfilled);

    @InspectorInstrumentation.promiseFulfilled(promise, value, reactions);

    @triggerPromiseReactions(@promiseStateFulfilled, reactions, value);
}

@globalPrivate
function createResolvingFunctions(promise)
{
    "use strict";

    var alreadyResolved = false;

    function @resolve(resolution) {
        if (alreadyResolved)
            return @undefined;
        alreadyResolved = true;

        if (resolution === promise)
            return @rejectPromise(promise, @makeTypeError("Resolve a promise with itself"));

        if (!@isObject(resolution))
            return @fulfillPromise(promise, resolution);

        var then;
        try {
            then = resolution.then;
        } catch (error) {
            return @rejectPromise(promise, error);
        }

        if (typeof then !== 'function')
            return @fulfillPromise(promise, resolution);

        @enqueueJob(@promiseResolveThenableJob, [promise, resolution, then]);

        return @undefined;
    }

    function @reject(reason) {
        if (alreadyResolved)
            return @undefined;
        alreadyResolved = true;

        return @rejectPromise(promise, reason);
    }

    return { @resolve, @reject };
}

@globalPrivate
function promiseReactionJob(state, reaction, argument)
{
    "use strict";

    var promiseCapability = reaction.@capabilities;

    var result;
    var handler = (state === @promiseStateFulfilled) ? reaction.@onFulfilled: reaction.@onRejected;
    try {
        result = handler(argument);
    } catch (error) {
        return promiseCapability.@reject.@call(@undefined, error);
    }

    return promiseCapability.@resolve.@call(@undefined, result);
}

@globalPrivate
function promiseResolveThenableJob(promiseToResolve, thenable, then)
{
    "use strict";

    var resolvingFunctions = @createResolvingFunctions(promiseToResolve);

    try {
        return then.@call(thenable, resolvingFunctions.@resolve, resolvingFunctions.@reject);
    } catch (error) {
        return resolvingFunctions.@reject.@call(@undefined, error);
    }
}

@globalPrivate
function initializePromise(executor)
{
    "use strict";

    if (typeof executor !== 'function')
        @throwTypeError("Promise constructor takes a function argument");

    @putByIdDirectPrivate(this, "promiseState", @promiseStatePending);
    @putByIdDirectPrivate(this, "promiseReactions", []);
    @putByIdDirectPrivate(this, "promiseIsHandled", false);

    var resolvingFunctions = @createResolvingFunctions(this);
    try {
        executor(resolvingFunctions.@resolve, resolvingFunctions.@reject);
    } catch (error) {
        return resolvingFunctions.@reject.@call(@undefined, error);
    }

    return this;
}