jsobject.h

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 *  Copyright (C) 1999-2001 Harri Porten ([e-mail])
 *  Copyright (C) 2001 Peter Kelly ([e-mail])
 *  Copyright (C) 2003, 2004, 2005, 2006, 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 JSObject_h
#define JSObject_h

#include "ArgList.h"
#include "ClassInfo.h"
#include "CommonIdentifiers.h"
#include "CallFrame.h"
#include "JSNumberCell.h"
#include "PropertySlot.h"
#include "PutPropertySlot.h"
#include "ScopeChain.h"
#include "Structure.h"

namespace JSC {

    class InternalFunction;
    class PropertyNameArray;
    class Structure;
    struct HashEntry;
    struct HashTable;

    // ECMA 262-3 8.6.1
    // Property attributes
    enum Attribute {
        None         = 0,
        ReadOnly     = 1 << 1,  // property can be only read, not written
        DontEnum     = 1 << 2,  // property doesn't appear in (for .. in ..)
        DontDelete   = 1 << 3,  // property can't be deleted
        Function     = 1 << 4,  // property is a function - only used by static hashtables
    };

    typedef JSValuePtr* PropertyStorage;

    class JSObject : public JSCell {
        friend class BatchedTransitionOptimizer;
        friend class JIT;
        friend class JSCell;

    public:
        explicit JSObject(PassRefPtr<Structure>);

        virtual void mark();

        // The inline virtual destructor cannot be the first virtual function declared
        // in the class as it results in the vtable being generated as a weak symbol
        virtual ~JSObject();

        bool inherits(const ClassInfo* classInfo) const { return JSCell::isObject(classInfo); }

        JSValuePtr prototype() const;
        void setPrototype(JSValuePtr prototype);
        
        void setStructure(PassRefPtr<Structure>);
        Structure* inheritorID();

        PropertyStorage& propertyStorage() { return m_propertyStorage; }

        virtual UString className() const;

        JSValuePtr get(ExecState*, const Identifier& propertyName) const;
        JSValuePtr get(ExecState*, unsigned propertyName) const;

        bool getPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
        bool getPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);

        virtual bool getOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
        virtual bool getOwnPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);

        virtual void put(ExecState*, const Identifier& propertyName, JSValuePtr value, PutPropertySlot&);
        virtual void put(ExecState*, unsigned propertyName, JSValuePtr value);

        virtual void putWithAttributes(ExecState*, const Identifier& propertyName, JSValuePtr value, unsigned attributes);
        virtual void putWithAttributes(ExecState*, unsigned propertyName, JSValuePtr value, unsigned attributes);

        bool propertyIsEnumerable(ExecState*, const Identifier& propertyName) const;

        bool hasProperty(ExecState*, const Identifier& propertyName) const;
        bool hasProperty(ExecState*, unsigned propertyName) const;
        bool hasOwnProperty(ExecState*, const Identifier& propertyName) const;

        virtual bool deleteProperty(ExecState*, const Identifier& propertyName);
        virtual bool deleteProperty(ExecState*, unsigned propertyName);

        virtual JSValuePtr defaultValue(ExecState*, PreferredPrimitiveType) const;

        virtual bool hasInstance(ExecState*, JSValuePtr, JSValuePtr prototypeProperty);

        virtual void getPropertyNames(ExecState*, PropertyNameArray&);

        virtual JSValuePtr toPrimitive(ExecState*, PreferredPrimitiveType = NoPreference) const;
        virtual bool getPrimitiveNumber(ExecState*, double& number, JSValuePtr& value);
        virtual bool toBoolean(ExecState*) const;
        virtual double toNumber(ExecState*) const;
        virtual UString toString(ExecState*) const;
        virtual JSObject* toObject(ExecState*) const;

        virtual JSObject* toThisObject(ExecState*) const;
        virtual JSObject* unwrappedObject();

        virtual bool getPropertyAttributes(ExecState*, const Identifier& propertyName, unsigned& attributes) const;

        // This get function only looks at the property map.
        JSValuePtr getDirect(const Identifier& propertyName) const
        {
            size_t offset = m_structure->get(propertyName);
            return offset != WTF::notFound ? m_propertyStorage[offset] : noValue();
        }

        JSValuePtr* getDirectLocation(const Identifier& propertyName)
        {
            size_t offset = m_structure->get(propertyName);
            return offset != WTF::notFound ? locationForOffset(offset) : 0;
        }

        JSValuePtr* getDirectLocation(const Identifier& propertyName, unsigned& attributes)
        {
            size_t offset = m_structure->get(propertyName, attributes);
            return offset != WTF::notFound ? locationForOffset(offset) : 0;
        }

        size_t offsetForLocation(JSValuePtr* location)
        {
            return location - m_propertyStorage;
        }

        JSValuePtr* locationForOffset(size_t offset)
        {
            return &m_propertyStorage[offset];
        }

        void transitionTo(Structure*);

        void removeDirect(const Identifier& propertyName);
        bool hasCustomProperties() { return !m_structure->isEmpty(); }
        bool hasGetterSetterProperties() { return m_structure->hasGetterSetterProperties(); }

        void putDirect(const Identifier& propertyName, JSValuePtr value, unsigned attr = 0);
        void putDirect(const Identifier& propertyName, JSValuePtr value, unsigned attr, bool checkReadOnly, PutPropertySlot& slot);
        void putDirectFunction(ExecState* exec, InternalFunction* function, unsigned attr = 0);
        void putDirectWithoutTransition(const Identifier& propertyName, JSValuePtr value, unsigned attr = 0);
        void putDirectFunctionWithoutTransition(ExecState* exec, InternalFunction* function, unsigned attr = 0);

        // Fast access to known property offsets.
        JSValuePtr getDirectOffset(size_t offset) { return m_propertyStorage[offset]; }
        void putDirectOffset(size_t offset, JSValuePtr value) { m_propertyStorage[offset] = value; }

        void fillGetterPropertySlot(PropertySlot&, JSValuePtr* location);

        virtual void defineGetter(ExecState*, const Identifier& propertyName, JSObject* getterFunction);
        virtual void defineSetter(ExecState*, const Identifier& propertyName, JSObject* setterFunction);
        virtual JSValuePtr lookupGetter(ExecState*, const Identifier& propertyName);
        virtual JSValuePtr lookupSetter(ExecState*, const Identifier& propertyName);

        virtual bool isGlobalObject() const { return false; }
        virtual bool isVariableObject() const { return false; }
        virtual bool isActivationObject() const { return false; }
        virtual bool isWatchdogException() const { return false; }
        virtual bool isNotAnObjectErrorStub() const { return false; }

        void allocatePropertyStorage(size_t oldSize, size_t newSize);
        void allocatePropertyStorageInline(size_t oldSize, size_t newSize);
        bool usingInlineStorage() const { return m_propertyStorage == m_inlineStorage; }

        static const size_t inlineStorageCapacity = 2;
        static const size_t nonInlineBaseStorageCapacity = 16;

        static PassRefPtr<Structure> createStructure(JSValuePtr prototype)
        {
            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot));
        }

    protected:
        bool getOwnPropertySlotForWrite(ExecState*, const Identifier&, PropertySlot&, bool& slotIsWriteable);

    private:
        bool inlineGetOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);

        const HashEntry* findPropertyHashEntry(ExecState*, const Identifier& propertyName) const;
        Structure* createInheritorID();

        RefPtr<Structure> m_inheritorID;

        PropertyStorage m_propertyStorage;        
        JSValuePtr m_inlineStorage[inlineStorageCapacity];
    };

    JSObject* asObject(JSValuePtr);

    JSObject* constructEmptyObject(ExecState*);

inline JSObject* asObject(JSValuePtr value)
{
    ASSERT(asCell(value)->isObject());
    return static_cast<JSObject*>(asCell(value));
}

inline JSObject::JSObject(PassRefPtr<Structure> structure)
    : JSCell(structure.releaseRef()) // ~JSObject balances this ref()
    , m_propertyStorage(m_inlineStorage)
{
    ASSERT(m_structure);
    ASSERT(m_structure->propertyStorageCapacity() == inlineStorageCapacity);
    ASSERT(m_structure->isEmpty());
    ASSERT(prototype().isNull() || Heap::heap(this) == Heap::heap(prototype()));
}

inline JSObject::~JSObject()
{
    ASSERT(m_structure);
    if (m_propertyStorage != m_inlineStorage)
        delete [] m_propertyStorage;
    m_structure->deref();
}

inline JSValuePtr JSObject::prototype() const
{
    return m_structure->storedPrototype();
}

inline void JSObject::setPrototype(JSValuePtr prototype)
{
    ASSERT(prototype);
    RefPtr<Structure> newStructure = Structure::changePrototypeTransition(m_structure, prototype);
    setStructure(newStructure.release());
}

inline void JSObject::setStructure(PassRefPtr<Structure> structure)
{
    m_structure->deref();
    m_structure = structure.releaseRef(); // ~JSObject balances this ref()
}

inline Structure* JSObject::inheritorID()
{
    if (m_inheritorID)
        return m_inheritorID.get();
    return createInheritorID();
}

inline bool JSCell::isObject(const ClassInfo* info) const
{
    for (const ClassInfo* ci = classInfo(); ci; ci = ci->parentClass) {
        if (ci == info)
            return true;
    }
    return false;
}

// this method is here to be after the inline declaration of JSCell::isObject
inline bool JSValuePtr::isObject(const ClassInfo* classInfo) const
{
    return isCell() && asCell()->isObject(classInfo);
}

ALWAYS_INLINE bool JSObject::inlineGetOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
{