JavaScriptCore/runtime/JSActivation.cpp

/*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
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 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"
#include "JSActivation.h"

#include "Arguments.h"
#include "Interpreter.h"
#include "JSFunction.h"

namespace JSC {

ASSERT_CLASS_FITS_IN_CELL(JSActivation);

const ClassInfo JSActivation::info = { "JSActivation", 0, 0, 0 };

JSActivation::JSActivation(CallFrame* callFrame, PassRefPtr<FunctionBodyNode> functionBody)
    : Base(callFrame->globalData().activationStructure, new JSActivationData(functionBody, callFrame->registers()))
{
}

JSActivation::~JSActivation()
{
    delete d();
}

void JSActivation::mark()
{
    Base::mark();

    Register* registerArray = d()->registerArray.get();
    if (!registerArray)
        return;

    size_t numParametersMinusThis = d()->functionBody->parameterCount();

    size_t i = 0;
    size_t count = numParametersMinusThis; 
    for ( ; i < count; ++i) {
        Register& r = registerArray[i];
        if (!r.marked())
            r.mark();
    }

    size_t numVars = d()->numVars;

    // Skip the call frame, which sits between the parameters and vars.
    i += RegisterFile::CallFrameHeaderSize;
    count += RegisterFile::CallFrameHeaderSize + numVars;

    for ( ; i < count; ++i) {
        Register& r = registerArray[i];
        if (r.jsValue() && !r.marked())
            r.mark();
    }
}

bool JSActivation::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
{
    if (symbolTableGet(propertyName, slot))
        return true;

    if (JSValue* location = getDirectLocation(propertyName)) {
        slot.setValueSlot(location);
        return true;
    }

    // Only return the built-in arguments object if it wasn't overridden above.
    if (propertyName == exec->propertyNames().arguments) {
        slot.setCustom(this, getArgumentsGetter());
        return true;
    }

    // We don't call through to JSObject because there's no way to give an 
    // activation object getter properties or a prototype.
    ASSERT(!hasGetterSetterProperties());
    ASSERT(prototype().isNull());
    return false;
}

void JSActivation::put(ExecState*, const Identifier& propertyName, JSValue value, PutPropertySlot& slot)
{
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));

    if (symbolTablePut(propertyName, value))
        return;

    // We don't call through to JSObject because __proto__ and getter/setter 
    // properties are non-standard extensions that other implementations do not
    // expose in the activation object.
    ASSERT(!hasGetterSetterProperties());
    putDirect(propertyName, value, 0, true, slot);
}

// FIXME: Make this function honor ReadOnly (const) and DontEnum
void JSActivation::putWithAttributes(ExecState* exec, const Identifier& propertyName, JSValue value, unsigned attributes)
{
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));

    if (symbolTablePutWithAttributes(propertyName, value, attributes))
        return;

    // We don't call through to JSObject because __proto__ and getter/setter 
    // properties are non-standard extensions that other implementations do not
    // expose in the activation object.
    ASSERT(!hasGetterSetterProperties());
    PutPropertySlot slot;
    JSObject::putWithAttributes(exec, propertyName, value, attributes, true, slot);
}

bool JSActivation::deleteProperty(ExecState* exec, const Identifier& propertyName)
{
    if (propertyName == exec->propertyNames().arguments)
        return false;

    return Base::deleteProperty(exec, propertyName);
}

JSObject* JSActivation::toThisObject(ExecState* exec) const
{
    return exec->globalThisValue();
}

bool JSActivation::isDynamicScope() const
{
    return d()->functionBody->usesEval();
}

JSValue JSActivation::argumentsGetter(ExecState* exec, const Identifier&, const PropertySlot& slot)
{
    JSActivation* activation = asActivation(slot.slotBase());

    if (activation->d()->functionBody->usesArguments()) {
        PropertySlot slot;
        activation->symbolTableGet(exec->propertyNames().arguments, slot);
        return slot.getValue(exec, exec->propertyNames().arguments);
    }

    CallFrame* callFrame = CallFrame::create(activation->d()->registers);
    Arguments* arguments = callFrame->optionalCalleeArguments();
    if (!arguments) {
        arguments = new (callFrame) Arguments(callFrame);
        arguments->copyRegisters();
        callFrame->setCalleeArguments(arguments);
    }
    ASSERT(arguments->isObject(&Arguments::info));

    return arguments;
}

// These two functions serve the purpose of isolating the common case from a
// PIC branch.

PropertySlot::GetValueFunc JSActivation::getArgumentsGetter()
{
    return argumentsGetter;
}

} // namespace JSC