Source/JavaScriptCore/runtime/GenericArguments.h

/*
 * Copyright (C) 2015-2019 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. 
 */

#pragma once

#include "CagedBarrierPtr.h"
#include "JSObject.h"

namespace JSC {

// This is a mixin for the two kinds of Arguments-class objects that arise when you say
// "arguments" inside a function. This class doesn't show up in the JSCell inheritance hierarchy.
template<typename Type>
class GenericArguments : public JSNonFinalObject {
public:
    typedef JSNonFinalObject Base;
    static constexpr unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | InterceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero | OverridesGetPropertyNames;

protected:
    GenericArguments(VM& vm, Structure* structure)
        : Base(vm, structure)
    {
    }

    static void visitChildren(JSCell*, SlotVisitor&);
    static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
    static bool getOwnPropertySlotByIndex(JSObject*, ExecState*, unsigned propertyName, PropertySlot&);
    static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
    static bool put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
    static bool putByIndex(JSCell*, ExecState*, unsigned propertyName, JSValue, bool shouldThrow);
    static bool deleteProperty(JSCell*, ExecState*, PropertyName);
    static bool deletePropertyByIndex(JSCell*, ExecState*, unsigned propertyName);
    static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
    
    void initModifiedArgumentsDescriptor(VM&, unsigned length);
    void initModifiedArgumentsDescriptorIfNecessary(VM&, unsigned length);
    void setModifiedArgumentDescriptor(VM&, unsigned index, unsigned length);
    bool isModifiedArgumentDescriptor(unsigned index, unsigned length);

    void copyToArguments(ExecState*, VirtualRegister firstElementDest, unsigned offset, unsigned length);

    using ModifiedArgumentsPtr = CagedBarrierPtr<Gigacage::Primitive, bool>;
    ModifiedArgumentsPtr m_modifiedArgumentsDescriptor;
};

} // namespace JSC