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#ifndef DeleteObserver_h__
#define DeleteObserver_h__

#include "prtypes.h"
class nsVoidArray;

//-------------------------------------------------------------------------
//
//-------------------------------------------------------------------------
//
// This is a small utility class which allows to notify an object
// (the "observer") holding a reference on another object 
// (the "observed") that the observed object has been deleted.
//
// As you imagine, it's reserved to cases where XPCOM refCouting doesn't fit.
// It is used by the MacEventHandler and the Toolkit to hold references
// on the focused widget and the the last widget hit.



//-------------------------------------------------------------------------
//
//-------------------------------------------------------------------------

class nsDeleteObserver
{
public:
		virtual void	NotifyDelete(void* aDeletedObject) = 0;
};

//-------------------------------------------------------------------------
//
//-------------------------------------------------------------------------

class nsDeleteObserved
{
public:
							nsDeleteObserved(void* aObject);
	virtual			~nsDeleteObserved();

	PRBool			AddDeleteObserver(nsDeleteObserver* aDeleteObserver);
	PRBool			RemoveDeleteObserver(nsDeleteObserver* aDeleteObserver);

private:
	nsVoidArray*			mDeleteObserverArray;
	void*							mObject;
};


#endif //DeleteObserver_h__