root/MMgc/GCWeakRef.h

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//
// GCWeakRef.h
// GC weak references (aka safe handles) as template classes
//

#ifndef _GC_WEAK_REF_H_
#define _GC_WEAK_REF_H_

namespace MMgc
{
        // new improved weak ref
        class GCWeakRef : public GCFinalizedObject
        {
                friend class GC;
        public:
                GCObject *get() { return (GCObject*)m_obj; }
                ~GCWeakRef() 
                { 
                        if(m_obj) {
                                GC::GetGC(this)->ClearWeakRef(m_obj); 
                        }
                }
        private:
                /**
                 * When allocating a GCWeakRef, tell the GC we don't contain pointers
                 * (overriding the default base-class behavior).
                 */
                static void *operator new(size_t size, GC *gc)
                {
                        return gc->Alloc(size, GC::kFinalize);
                }

                // private, only GC can access
                GCWeakRef(const void *obj) : m_obj(obj) 
                {
#ifdef MMGC_MEMORY_INFO
                        obj_creation = obj;
#endif
                }
                const void *m_obj;
#ifdef MMGC_MEMORY_INFO
                const void* obj_creation;
#endif
        };

#if 0
        // something like this would be nice
        template<class T> class GCWeakRefPtr 
        {
                
        public:
                GCWeakRefPtr() {}
                GCWeakRefPtr(T t) {  set(t);}
                ~GCWeakRefPtr() { t = NULL;     }

                T operator=(const GCWeakRefPtr<T>& wb)
                {
                        return set(wb.t);       
                }

                T operator=(T tNew)
                {
                        return set(tNew);
                }

                operator T() const { return (T) t->get(); }

                bool operator!=(T other) const { return other != t; }

                T operator->() const
                {
                        return (T) t->get();
                }
        private:                
                T set(const T tNew)
                {
                        t = tNew->GetWeakRef();
                }
                GCWeakRef* t;
        };
#endif
}

#endif // _GC_WEAK_REF_H_