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/*
* DNN - Data News Network
*
* by Stephane Chatty
*
* Copyright 1993-1995
* Centre d'Etudes de la Navigation Aerienne (CENA)
*
* Event triggers.
*
* $Id$
* $CurLog$
*/
#include "Trigger.h"
#include "Reaction.h"
#include "Criterion.h"
/*?class IvlTrigger
\typ{IvlTrigger}s are the core of event detection and emission. The presence of a trigger
(generally in a sensor) determines whether a certain situation, or the reception
of an event from the underlying window system, should provoke the emission of an event.
Each trigger holds a list of reactions (of type \typ{IvlBaseReaction}). These reactions will
receive all the events whose creation and emission was caused by the presence of
the trigger.
?*/
/*?
Create a trigger with an empty list of associated reaction.
?*/
IvlTrigger :: IvlTrigger ()
: FirstSubscribers (),
LastSubscribers (),
Subscribers (),
Grabs (),
Criteria ()
{
}
/*?nodoc?*/
IvlTrigger :: ~IvlTrigger ()
{
/* Force reactions to unsubscribe.
We should take care of conditions when destructor is called
during iteration */
IvlListIterOf <IvlBaseReaction> ri = FirstSubscribers;
while (++ri)
(*ri)->Forget (*this);
ri = Subscribers;
while (++ri)
(*ri)->Forget (*this);
ri = LastSubscribers;
while (++ri)
(*ri)->Forget (*this);
ri = Grabs;
while (++ri)
(*ri)->Forget (*this);
}
/*?nextdoc?*/
void
IvlTrigger :: Subscribe (IvlBaseReaction& a, REL_PRIORITY p)
{
switch (p) {
case isFirstPriority:
FirstSubscribers.Append (&a);
break;
case isNormalPriority:
Subscribers.Append (&a);
break;
case isLastPriority:
LastSubscribers.Prepend (&a);
break;
}
}
/*?
Add (resp. Remove) a reaction to (resp. from) the list of reactions that should receive
events caused by this trigger.
?*/
void
IvlTrigger :: Unsubscribe (IvlBaseReaction& a)
{
FirstSubscribers.Remove (&a);
Subscribers.Remove (&a);
LastSubscribers.Remove (&a);
Grabs.Remove (&a);
}
/*?nextdoc?*/
void
IvlTrigger :: Grab (IvlBaseReaction& a)
{
Grabs.Prepend (&a);
}
/*?
Add (resp. Remove) a reaction onto (resp. from) the stack of reactions that preempt
events caused by this trigger.
?*/
void
IvlTrigger :: Release (IvlBaseReaction& a)
{
Grabs.Remove (&a);
}
#if 0
void
IvlTrigger :: Circulate (IvlBaseReaction& r, REL_POS pos, IvlBaseReaction* ref)
{
if (Subscribers.Remove (&r)) {
/* find the predecessor of ref */
IvlListIterOf <IvlBaseReaction> lc = Subscribers;
while (++lc && (*lc != ref))
;
/* NOW, lc is on ref, or at the end if ref == 0 */
if (pos == isBefore)
Subscribers.InsertBefore (lc, &r);
else
Subscribers.InsertAfter (lc, &r);
}
}
#endif
/*?
Have a trigger dispatch the event \var{ev} to its associated reactions.
?*/
void
IvlTrigger :: Dispatch (IvlEvent& ev)
{
IvlBaseReaction* r = Grabs.First ();
if (r) {
r->Manage (ev);
} else {
/* calls to Manage may result in changes in Subscribers; let's make a safe copy */
IvlListOf <IvlBaseReaction> first_subscribers = FirstSubscribers;
IvlListOf <IvlBaseReaction> subscribers = Subscribers;
IvlListOf <IvlBaseReaction> last_subscribers = LastSubscribers;
IvlListIterOf <IvlBaseReaction> s = first_subscribers;
while (++s)
#ifdef CRITERIA_IN_REACTIONS
if ((*s)->Check (ev))
#endif
(*s)->Manage (ev);
s = subscribers;
while (++s)
#ifdef CRITERIA_IN_REACTIONS
if ((*s)->Check (ev))
#endif
(*s)->Manage (ev);
s = last_subscribers;
while (++s)
#ifdef CRITERIA_IN_REACTIONS
if ((*s)->Check (ev))
#endif
(*s)->Manage (ev);
}
}
bool
IvlTrigger :: Check (IvlEvent& ev)
{
IvlListIterOf <IvlBaseCriterion> c = Criteria;
while (++c)
if (!(*c)->Test (ev))
return false;
#ifdef CRITERIA_IN_REACTIONS
IvlListIterOf <IvlBaseReaction> ri = FirstSubscribers;
while (++ri)
if ((*ri)->Check (ev))
return true;
ri = Subscribers;
while (++ri)
if ((*ri)->Check (ev))
return true;
ri = LastSubscribers;
while (++ri)
if ((*ri)->Check (ev))
return true;
return false;
#else
return true;
#endif
}
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