Source/JavaScriptCore/builtins/TypedArrayConstructor.js

/*
 * Copyright (C) 2015 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.
 */

// According to the spec we are supposed to crawl the prototype chain looking
// for the a TypedArray constructor. The way we implement this is with a
// private function, @alloctateTypedArray, on each of the prototypes.
// This enables us to optimize this lookup in the inline cache.

function of(/* items... */)
{
    "use strict";
    let len = arguments.length;
    let constructFunction = @getByIdDirectPrivate(this, "allocateTypedArray");
    if (constructFunction === @undefined)
        @throwTypeError("TypedArray.of requires its this argument to subclass a TypedArray constructor");

    let result = constructFunction(len);

    for (let i = 0; i < len; i++)
        result[i] = arguments[i];

    return result;
}

function from(items /* [ , mapfn [ , thisArg ] ] */)
{
    "use strict";

    let mapFn = @argument(1);

    let thisArg;

    if (mapFn !== @undefined) {
        if (typeof mapFn !== "function")
            @throwTypeError("TypedArray.from requires that the second argument, when provided, be a function");

        thisArg = @argument(2);
    }

    let arrayLike = @toObject(items, "TypedArray.from requires an array-like object - not null or undefined");

    let iteratorMethod = items.@iteratorSymbol;
    if (iteratorMethod != null) {
        if (typeof iteratorMethod !== "function")
            @throwTypeError("TypedArray.from requires that the property of the first argument, items[Symbol.iterator], when exists, be a function");

        let accumulator = [];

        let k = 0;
        let iterator = iteratorMethod.@call(items);

        // Since for-of loop once more looks up the @@iterator property of a given iterable,
        // it could be observable if the user defines a getter for @@iterator.
        // To avoid this situation, we define a wrapper object that @@iterator just returns a given iterator.
        let wrapper = {};
        wrapper.@iteratorSymbol = function() { return iterator; }

        for (let value of wrapper) {
            if (mapFn)
                @putByValDirect(accumulator, k, thisArg === @undefined ? mapFn(value, k) : mapFn.@call(thisArg, value, k));
            else
                @putByValDirect(accumulator, k, value);
            k++;
        }

        let constructFunction = @getByIdDirectPrivate(this, "allocateTypedArray");
        if (constructFunction === @undefined)
            @throwTypeError("TypedArray.from requires its this argument subclass a TypedArray constructor");

        let result = constructFunction(k);

        for (let i = 0; i < k; i++) 
            result[i] = accumulator[i];


        return result;
    }

    let arrayLikeLength = @toLength(arrayLike.length);

    let constructFunction = @getByIdDirectPrivate(this, "allocateTypedArray");
    if (constructFunction === @undefined)
        @throwTypeError("this does not subclass a TypedArray constructor");

    let result = constructFunction(arrayLikeLength);

    let k = 0;
    while (k < arrayLikeLength) {
        let value = arrayLike[k];
        if (mapFn)
            result[k] = thisArg === @undefined ? mapFn(value, k) : mapFn.@call(thisArg, value, k);
        else
            result[k] = value;
        k++;
    }

    return result;
}

function allocateInt8Array(length)
{
    return new @Int8Array(length);
}

function allocateInt16Array(length)
{
    return new @Int16Array(length);    
}

function allocateInt32Array(length)
{
    return new @Int32Array(length);   
}

function allocateUint32Array(length)
{
    return new @Uint32Array(length);
}

function allocateUint16Array(length)
{
    return new @Uint16Array(length);   
}

function allocateUint8Array(length)
{
    return new @Uint8Array(length);   
}

function allocateUint8ClampedArray(length)
{
    return new @Uint8ClampedArray(length);
}

function allocateFloat32Array(length)
{
    return new @Float32Array(length);
}

function allocateFloat64Array(length)
{
    return new @Float64Array(length);
}