Source/WebCore/Modules/streams/TransformStream.js

/*
 * Copyright (C) 2020 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. AND ITS CONTRIBUTORS ``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 ITS 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.
 */

function initializeTransformStream()
{
    "use strict";

    let transformer = arguments[0];

    // This is the path for CreateTransformStream.
    if (@isObject(transformer) && @getByIdDirectPrivate(transformer, "TransformStream"))
        return this;

    let writableStrategy = arguments[1];
    let readableStrategy = arguments[2];

    if (transformer === @undefined)
        transformer = null;

    if (readableStrategy === @undefined)
        readableStrategy = { };

    if (writableStrategy === @undefined)
        writableStrategy = { };

    let transformerDict = { };
    if (transformer !== null) {
        if ("start" in transformer) {
            transformerDict["start"] = transformer["start"];
            if (typeof transformerDict["start"] !== "function")
                @throwTypeError("transformer.start should be a function");
        }
        if ("transform" in transformer) {
            transformerDict["transform"] = transformer["transform"];
            if (typeof transformerDict["transform"] !== "function")
                @throwTypeError("transformer.transform should be a function");
        }
        if ("flush" in transformer) {
            transformerDict["flush"] = transformer["flush"];
            if (typeof transformerDict["flush"] !== "function")
                @throwTypeError("transformer.flush should be a function");
        }

        if ("readableType" in transformer)
            @throwRangeError("TransformStream transformer has a readableType");
        if ("writableType" in transformer)
            @throwRangeError("TransformStream transformer has a writableType");
    }

    const readableHighWaterMark = @extractHighWaterMark(readableStrategy, 0);
    const readableSizeAlgorithm = @extractSizeAlgorithm(readableStrategy);

    const writableHighWaterMark = @extractHighWaterMark(writableStrategy, 1);
    const writableSizeAlgorithm = @extractSizeAlgorithm(writableStrategy);

    const startPromiseCapability = @newPromiseCapability(@Promise);
    @initializeTransformStream(this, startPromiseCapability.@promise, writableHighWaterMark, writableSizeAlgorithm, readableHighWaterMark, readableSizeAlgorithm);
    @setUpTransformStreamDefaultControllerFromTransformer(this, transformer, transformerDict);

    if ("start" in transformerDict) {
        const controller = @getByIdDirectPrivate(this, "controller");
        const startAlgorithm = () => @promiseInvokeOrNoopMethodNoCatch(transformer, transformerDict["start"], [controller]);
        startAlgorithm().@then(() => {
            // FIXME: We probably need to resolve start promise with the result of the start algorithm.
            startPromiseCapability.@resolve.@call();
        }, (error) => {
            startPromiseCapability.@reject.@call(@undefined, error);
        });
    } else
        startPromiseCapability.@resolve.@call();

    return this;
}

@getter
function readable()
{
    "use strict";

    if (!@isTransformStream(this))
        throw @makeThisTypeError("TransformStream", "readable");

    return @getByIdDirectPrivate(this, "readable");
}

function writable()
{
    "use strict";

    if (!@isTransformStream(this))
        throw @makeThisTypeError("TransformStream", "writable");

    return @getByIdDirectPrivate(this, "writable");
}