Source/JavaScriptCore/runtime/JSActivation.cpp

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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, NonNullPassRefPtr<FunctionExecutable> functionExecutable)
    : Base(callFrame->globalData().activationStructure, new JSActivationData(functionExecutable, callFrame->registers()))
{
}

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

void JSActivation::markChildren(MarkStack& markStack)
{
    Base::markChildren(markStack);

    // No need to mark our registers if they're still in the RegisterFile.
    Register* registerArray = d()->registerArray.get();
    if (!registerArray)
        return;

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

    size_t count = numParametersMinusThis;
    markStack.appendValues(registerArray, count);

    size_t numVars = d()->functionExecutable->capturedVariableCount();

    // Skip the call frame, which sits between the parameters and vars.
    markStack.appendValues(registerArray + count + RegisterFile::CallFrameHeaderSize, numVars, MayContainNullValues);
}

inline bool JSActivation::symbolTableGet(const Identifier& propertyName, PropertySlot& slot)
{
    SymbolTableEntry entry = symbolTable().inlineGet(propertyName.impl());
    if (!entry.isNull()) {
        ASSERT(entry.getIndex() < static_cast<int>(d()->functionExecutable->capturedVariableCount()));
        slot.setRegisterSlot(&registerAt(entry.getIndex()));
        return true;
    }
    return false;
}

inline bool JSActivation::symbolTablePut(const Identifier& propertyName, JSValue value)
{
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
    
    SymbolTableEntry entry = symbolTable().inlineGet(propertyName.impl());
    if (entry.isNull())
        return false;
    if (entry.isReadOnly())
        return true;
    ASSERT(entry.getIndex() < static_cast<int>(d()->functionExecutable->capturedVariableCount()));
    registerAt(entry.getIndex()) = value;
    return true;
}

void JSActivation::getOwnPropertyNames(ExecState* exec, PropertyNameArray& propertyNames, EnumerationMode mode)
{
    SymbolTable::const_iterator end = symbolTable().end();
    for (SymbolTable::const_iterator it = symbolTable().begin(); it != end; ++it) {
        ASSERT(it->second.getIndex() < static_cast<int>(d()->functionExecutable->capturedVariableCount()));
        if (!(it->second.getAttributes() & DontEnum) || (mode == IncludeDontEnumProperties))
            propertyNames.add(Identifier(exec, it->first.get()));
    }
    // Skip the JSVariableObject implementation of getOwnPropertyNames
    JSObject::getOwnPropertyNames(exec, propertyNames, mode);
}

inline bool JSActivation::symbolTablePutWithAttributes(const Identifier& propertyName, JSValue value, unsigned attributes)
{
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
    
    SymbolTable::iterator iter = symbolTable().find(propertyName.impl());
    if (iter == symbolTable().end())
        return false;
    SymbolTableEntry& entry = iter->second;
    ASSERT(!entry.isNull());
    if (entry.getIndex() >= static_cast<int>(d()->functionExecutable->capturedVariableCount()))
        return false;
    entry.setAttributes(attributes);
    registerAt(entry.getIndex()) = value;
    return true;
}

bool JSActivation::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
{
    if (propertyName == exec->propertyNames().arguments) {
        slot.setCustom(this, getArgumentsGetter());
        return true;
    }

    if (symbolTableGet(propertyName, slot))
        return true;

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

JSValue JSActivation::toStrictThisObject(ExecState*) const
{
    return jsNull();
}
    
bool JSActivation::isDynamicScope(bool& requiresDynamicChecks) const
{
    requiresDynamicChecks = d()->functionExecutable->usesEval();
    return false;
}

JSValue JSActivation::argumentsGetter(ExecState*, JSValue slotBase, const Identifier&)
{
    JSActivation* activation = asActivation(slotBase);
    CallFrame* callFrame = CallFrame::create(activation->d()->registers);
    int argumentsRegister = activation->d()->functionExecutable->generatedBytecode().argumentsRegister();
    if (JSValue arguments = callFrame->uncheckedR(argumentsRegister).jsValue())
        return arguments;
    int realArgumentsRegister = unmodifiedArgumentsRegister(argumentsRegister);

    JSValue arguments = JSValue(new (callFrame) Arguments(callFrame));
    callFrame->uncheckedR(argumentsRegister) = arguments;
    callFrame->uncheckedR(realArgumentsRegister) = arguments;
    
    ASSERT(callFrame->uncheckedR(realArgumentsRegister).jsValue().inherits(&Arguments::info));
    return callFrame->uncheckedR(realArgumentsRegister).jsValue();
}

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

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

} // namespace JSC