Source/WebCore/bindings/v8/custom/V8ArrayBufferCustom.cpp

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 *
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 * in the documentation and/or other materials provided with the
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "config.h"
#include "V8ArrayBufferCustom.h"

#include <wtf/ArrayBuffer.h>
#include <wtf/StdLibExtras.h>

#include "ExceptionCode.h"
#include "V8ArrayBuffer.h"
#include "V8Binding.h"

namespace WebCore {

V8ArrayBufferDeallocationObserver* V8ArrayBufferDeallocationObserver::instance()
{
    DEFINE_STATIC_LOCAL(V8ArrayBufferDeallocationObserver, deallocationObserver, ());
    return &deallocationObserver;
}


v8::Handle<v8::Value> V8ArrayBuffer::constructorCallback(const v8::Arguments& args)
{
    INC_STATS("DOM.ArrayBuffer.Constructor");

    if (!args.IsConstructCall())
        return throwTypeError("DOM object constructor cannot be called as a function.", args.GetIsolate());

    if (ConstructorMode::current() == ConstructorMode::WrapExistingObject)
        return args.Holder();

    // If we return a previously constructed ArrayBuffer,
    // e.g. from the call to ArrayBufferView.buffer, this code is called
    // with a zero-length argument list. The V8DOMWrapper will then
    // set the internal pointer in the newly-created object.
    // Unfortunately it doesn't look like it's possible to distinguish
    // between this case and that where the user calls "new
    // ArrayBuffer()" from JavaScript. To guard against problems,
    // we always create at least a zero-length ArrayBuffer, even
    // if it is immediately overwritten by the V8DOMWrapper.

    // Supported constructors:
    // ArrayBuffer(n) where n is an integer:
    //   -- create an empty buffer of n bytes

    int argLength = args.Length();
    int length = 0;
    if (argLength > 0)
        length = toInt32(args[0]); // NaN/+inf/-inf returns 0, this is intended by WebIDL
    RefPtr<ArrayBuffer> buffer;
    if (length >= 0)
        buffer = ArrayBuffer::create(static_cast<unsigned>(length), 1);
    if (!buffer.get())
        return throwError(RangeError, "ArrayBuffer size is not a small enough positive integer.", args.GetIsolate());
    buffer->setDeallocationObserver(V8ArrayBufferDeallocationObserver::instance());
    v8::V8::AdjustAmountOfExternalAllocatedMemory(buffer->byteLength());
    // Transform the holder into a wrapper object for the array.
    v8::Handle<v8::Object> wrapper = args.Holder();
    V8DOMWrapper::setDOMWrapper(wrapper, &info, buffer.get());
    V8DOMWrapper::setJSWrapperForDOMObject(buffer.release(), wrapper);
    return wrapper;
}

} // namespace WebCore