/*
 *	DNN - Data News Network
 *
 *	by Stephane Chatty
 *
 *	Copyright 1993-1997
 *	Centre d'Etudes de la Navigation Aerienne (CENA)
 *
 *	Reactions.
 *
 *	$Id$
 *	$CurLog$
 */

#include "Reaction.h"
#include "Trigger.h"

/*?class DnnBaseReaction
The class \typ{DnnBaseReaction} is the base class for event handling.
A reaction implements a behaviour (through the virtual function \fun{Manage}),
and can be associated to one or more triggers, generally located in a sensor.
?*/

/*?
Create a reaction.
?*/
DnnBaseReaction :: DnnBaseReaction ()
: Triggers (),
  Grabbed ()
{
}

/*?nodoc?*/
DnnBaseReaction :: ~DnnBaseReaction ()
{
	CcuListIterOf <DnnTrigger> ti = Grabbed;
	while (++ti)
		(*ti)->Release (*this);

	ti = Triggers;
	while (++ti)
		(*ti)->Unsubscribe (*this);
}

/*!
Tell a reaction to forget a trigger. This special function is used only
when destroying a trigger.
!*/
void
DnnBaseReaction :: Forget (DnnTrigger& t)
{
	Triggers.Remove (&t);
	Grabbed.Remove (&t);
}

/*?nextdoc?*/
void
DnnBaseReaction :: SubscribeTo (DnnTrigger& t, REL_PRIORITY p)
{
	Triggers.Append (&t);
	t.Subscribe (*this, (DnnTrigger::REL_PRIORITY) p);
}

/*?
Tell that a reaction should (resp. should no more) be activated when the trigger \var{t}
causes the emission of an event.
?*/
void
DnnBaseReaction :: UnsubscribeTo (DnnTrigger& t)
{
	Triggers.Remove (&t);
	t.Unsubscribe (*this);
}

/*?nextdoc?*/
void
DnnBaseReaction :: Grab (DnnTrigger& t)
{
	Grabbed.Append (&t);
	t.Grab (*this);
}

/*?
Tell that a reaction should (resp. should no more) be the only one
activated when the trigger \var{t} causes the emission of an event.
?*/
void
DnnBaseReaction :: Release (DnnTrigger& t)
{
	Grabbed.Remove (&t);
	t.Release (*this);
}

/*?
This virtual function is called when an event is emitted because of a trigger to which
this reaction was attached. It should be redefined in derived classes to implement
behaviours.
?*/
void
DnnBaseReaction :: Manage (DnnEvent&)
{
}

/*?class DnnCallback
The class \typ{DnnCallback} is a ready-to-use derived class of \typ{DnnBaseReaction}.
In this class, the function \fun{Manage} is redefined to call a function passed when creating
the reaction.
?*/

/*?
Build a reaction that will call \var{f} to handle events.
\fun{f} has to take a \typ{DnnEvent\&} parameter and return \typ{void}.
?*/
DnnCallback :: DnnCallback (DnnHandlingFunction f)
: DnnBaseReaction (),
  Handler (f)
{
}

/*?nodoc?*/
DnnCallback :: ~DnnCallback ()
{
}

/*?nodoc?*/
void
DnnCallback :: Manage (DnnEvent& ev)
{
	(*Handler) (ev);
}