Source/JavaScriptCore/runtime/JSNotAnObject.h

/*
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#ifndef JSNotAnObject_h
#define JSNotAnObject_h

#include "JSObject.h"

namespace JSC {

    // This unholy class is used to allow us to avoid multiple exception checks
    // in certain SquirrelFish bytecodes -- effectively it just silently consumes
    // any operations performed on the result of a failed toObject call.
    class JSNotAnObject : public JSNonFinalObject {
    public:
        JSNotAnObject(ExecState* exec)
            : JSNonFinalObject(exec->globalData().notAnObjectStructure)
        {
        }

        static PassRefPtr<Structure> createStructure(JSGlobalData& globalData, JSValue prototype)
        {
            return Structure::create(globalData, prototype, TypeInfo(ObjectType, StructureFlags), AnonymousSlotCount, &s_info);
        }

     private:
        
        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesGetPropertyNames | JSObject::StructureFlags;

        // JSValue methods
        virtual JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
        virtual bool getPrimitiveNumber(ExecState*, double& number, JSValue&);
        virtual bool toBoolean(ExecState*) const;
        virtual double toNumber(ExecState*) const;
        virtual UString toString(ExecState*) const;
        virtual JSObject* toObject(ExecState*, JSGlobalObject*) const;

        // JSObject methods
        virtual bool getOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
        virtual bool getOwnPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
        virtual bool getOwnPropertyDescriptor(ExecState*, const Identifier&, PropertyDescriptor&);

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

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

        virtual void getOwnPropertyNames(ExecState*, PropertyNameArray&, EnumerationMode mode = ExcludeDontEnumProperties);
    };

} // namespace JSC

#endif // JSNotAnObject_h