/*

 *  Copyright (C) 2005, 2007, 2008 Apple Inc. All rights reserved.

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Library General Public

 *  License as published by the Free Software Foundation; either

 *  version 2 of the License, or (at your option) any later version.

 *

 *  This library is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 *  Library General Public License for more details.

 *

 *  You should have received a copy of the GNU Library General Public License

 *  along with this library; see the file COPYING.LIB.  If not, write to

 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 *  Boston, MA 02110-1301, USA.

 *

 */

#ifndef PropertySlot_h

#define PropertySlot_h

#include "Identifier.h"

#include "JSValue.h"

#include "Register.h"

#include <wtf/Assertions.h>

#include <wtf/NotFound.h>

namespace JSC {

    class ExecState;

    class JSObject;

#define JSC_VALUE_SLOT_MARKER 0

#define JSC_REGISTER_SLOT_MARKER reinterpret_cast<GetValueFunc>(1)

    class PropertySlot {

    public:

        PropertySlot()

        {

            clearBase();

            clearOffset();

            clearValue();

        }

        explicit PropertySlot(const JSValue base)

            : m_slotBase(base)

        {

            clearOffset();

            clearValue();

        }

        typedef JSValue (*GetValueFunc)(ExecState*, const Identifier&, const PropertySlot&);

        JSValue getValue(ExecState* exec, const Identifier& propertyName) const

        {

            if (m_getValue == JSC_VALUE_SLOT_MARKER)

                return *m_data.valueSlot;

            if (m_getValue == JSC_REGISTER_SLOT_MARKER)

                return (*m_data.registerSlot).jsValue();

            return m_getValue(exec, propertyName, *this);

        }

        JSValue getValue(ExecState* exec, unsigned propertyName) const

        {

            if (m_getValue == JSC_VALUE_SLOT_MARKER)

                return *m_data.valueSlot;

            if (m_getValue == JSC_REGISTER_SLOT_MARKER)

                return (*m_data.registerSlot).jsValue();

            return m_getValue(exec, Identifier::from(exec, propertyName), *this);

        }

        bool isCacheable() const { return m_offset != WTF::notFound; }

        size_t cachedOffset() const

        {

            ASSERT(isCacheable());

            return m_offset;

        }

        void setValueSlot(JSValue* valueSlot) 

        {

            ASSERT(valueSlot);

            clearBase();

            clearOffset();

            m_getValue = JSC_VALUE_SLOT_MARKER;

            m_data.valueSlot = valueSlot;

        }

        void setValueSlot(JSValue slotBase, JSValue* valueSlot)

        {

            ASSERT(valueSlot);

            m_getValue = JSC_VALUE_SLOT_MARKER;

            m_slotBase = slotBase;

            m_data.valueSlot = valueSlot;

        }

        void setValueSlot(JSValue slotBase, JSValue* valueSlot, size_t offset)

        {

            ASSERT(valueSlot);

            m_getValue = JSC_VALUE_SLOT_MARKER;

            m_slotBase = slotBase;

            m_data.valueSlot = valueSlot;

            m_offset = offset;

        }

        void setValue(JSValue value)

        {

            ASSERT(value);

            clearBase();

            clearOffset();

            m_getValue = JSC_VALUE_SLOT_MARKER;

            m_value = value;

            m_data.valueSlot = &m_value;

        }

        void setRegisterSlot(Register* registerSlot)

        {

            ASSERT(registerSlot);

            clearBase();

            clearOffset();

            m_getValue = JSC_REGISTER_SLOT_MARKER;

            m_data.registerSlot = registerSlot;

        }

        void setCustom(JSValue slotBase, GetValueFunc getValue)

        {

            ASSERT(slotBase);

            ASSERT(getValue);

            m_getValue = getValue;

            m_slotBase = slotBase;

        }

        void setCustomIndex(JSValue slotBase, unsigned index, GetValueFunc getValue)

        {

            ASSERT(slotBase);

            ASSERT(getValue);

            m_getValue = getValue;

            m_slotBase = slotBase;

            m_data.index = index;

        }

        void setGetterSlot(JSObject* getterFunc)

        {

            ASSERT(getterFunc);

            m_getValue = functionGetter;

            m_data.getterFunc = getterFunc;

        }

        void setUndefined()

        {

            setValue(jsUndefined());

        }

        JSValue slotBase() const

        {

            return m_slotBase;

        }

        void setBase(JSValue base)

        {

            ASSERT(m_slotBase);

            ASSERT(base);

            m_slotBase = base;

        }

        void clearBase()

        {

#ifndef NDEBUG

            m_slotBase = JSValue();

#endif

        }

        void clearValue()

        {

#ifndef NDEBUG

            m_value = JSValue();

#endif

        }

        void clearOffset()

        {

            // Clear offset even in release builds, in case this PropertySlot has been used before.

            // (For other data members, we don't need to clear anything because reuse would meaningfully overwrite them.)

            m_offset = WTF::notFound;

        }

        unsigned index() const { return m_data.index; }

    private:

        static JSValue functionGetter(ExecState*, const Identifier&, const PropertySlot&);

        GetValueFunc m_getValue;

        JSValue m_slotBase;

        union {

            JSObject* getterFunc;

            JSValue* valueSlot;

            Register* registerSlot;

            unsigned index;

        } m_data;

        JSValue m_value;

        size_t m_offset;

    };

} // namespace JSC

#endif // PropertySlot_h