/*
 *	DNN - Data News Network
 *
 *	by Stephane Chatty
 *
 *	Copyright 1993-1995
 *	Centre d'Etudes de la Navigation Aerienne (CENA)
 *
 *	Event triggers.
 *
 *	$Id$
 *	$CurLog$
 */

#ifndef DnnTrigger_H_
#define DnnTrigger_H_

#include "cplus_bugs.h"
#include "ccu/List.h"
#include "ccu/bool.h"

class DnnEvent;
class DnnBaseCriterion;

class DnnTrigger {
friend	class	DnnBaseReaction;

public:
enum	REL_PRIORITY { isFirstPriority, isNormalPriority, isLastPriority };

private:
		DnnTrigger (const DnnTrigger&);
	DnnTrigger&	operator = (const DnnTrigger&);

protected:
	CcuListOf <DnnBaseReaction>	FirstSubscribers;
	CcuListOf <DnnBaseReaction>	Subscribers;
	CcuListOf <DnnBaseReaction>	LastSubscribers;
	CcuListOf <DnnBaseReaction>	Grabs;
	CcuListOf <DnnBaseCriterion>	Criteria;
	void	Subscribe (DnnBaseReaction&, REL_PRIORITY);
	void	Unsubscribe (DnnBaseReaction&);
	void	Grab (DnnBaseReaction&);
	void	Release (DnnBaseReaction&);

public:
		DnnTrigger ();
		~DnnTrigger ();
inline	bool	IsUnused () const	{ return bool (Subscribers.IsEmpty () && FirstSubscribers.IsEmpty () && LastSubscribers.IsEmpty ()); }
	void	Dispatch (DnnEvent&);
	bool	Check (DnnEvent&);
inline	void	AddCriterion    (DnnBaseCriterion& c) { Criteria.Append (&c); }
inline	void	RemoveCriterion (DnnBaseCriterion& c) { Criteria.Remove (&c); }
};

#endif	/* DnnTrigger_H_ */