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include/platform/memory/nweak_ptr.h

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+/* -----------------------------------------------------------------------------
+	GSFramework
+	Copyright 2001-2013 Emmanuel Julien. All Rights Reserved.
+----------------------------------------------------------------------------- */
+
+
+#ifndef	__NWEAK_PTR__
+#define __NWEAK_PTR__
+
+
+		#include "memory/nshared_ptr.h"
+
+
+namespace GS {
+
+/*!
+	@short	Weak pointer to a reference counted object.
+	@author	Emmanuel Julien (ejulien@gsworks.fr)
+*/
+template <class T> class WeakPtr
+{
+private:
+
+		T			*rc_o;
+		WeakRef		*wref;
+
+public:
+
+		T			*c_ptr() const { return wref && wref->IsValid() ? rc_o : 0; }
+
+		bool		IsValid() const { return wref && wref->IsValid() ? true : false; }
+		bool		IsNull() const { return !IsValid(); }
+
+		/// Lock pointed object to a strong pointer.
+		bool		Lock(SharedPtr <T> &p)
+		{
+			if	(IsNull())
+				return false;
+			p = rc_o;
+			return true;
+		}
+		SharedPtr <T> Lock() const { return SharedPtr <T> (IsValid() ? rc_o : 0); }
+
+		void		Init()
+		{
+			if	(!rc_o)
+				wref = 0;
+			else
+			{
+				wref = rc_o->GetWeakRef();
+				wref->AddRef();
+			}
+		}
+
+inline	bool		operator == (const T *p) const
+		{	return rc_o == p;	}
+inline	bool		operator != (const T *p) const
+		{	return rc_o != p;	}
+inline	bool		operator == (T *p) const
+		{	return rc_o == p;	}
+inline	bool		operator != (T *p) const
+		{	return rc_o != p;	}
+
+inline	bool		operator == (const WeakPtr &p) const
+		{	return rc_o == p.rc_o;	}
+inline	bool		operator != (const WeakPtr &p) const
+		{	return rc_o != p.rc_o;	}
+
+		WeakPtr <T> &operator = (const WeakPtr &p)
+		{
+			if	(rc_o != p.rc_o)
+			{
+				WeakRef *old_wref = wref;
+
+				rc_o = p.rc_o;
+				Init();
+
+				if	(old_wref)
+					old_wref->RemoveRef();
+			}
+			return *this;
+		}
+inline	T			*operator -> () const
+		{	return rc_o;	}
+inline	T			&operator * () const
+		{	return *rc_o;	}
+
+		WeakPtr(T *p = 0) : rc_o(p) { Init(); }
+		WeakPtr(const WeakPtr &p) : rc_o(p.rc_o) { Init(); }
+		WeakPtr(const SharedPtr <T> &p) : rc_o(p.c_ptr()) { Init(); }
+		~WeakPtr()
+		{
+			if	(wref)
+				wref->RemoveRef();
+		}
+};
+
+} // GS
+
+
+#endif	// __NWEAK_PTR__