/**
* Fires a transition in this marking. Changes this marking.
*
* @param transition transition to be fired in the marking
* @return false if the specified transition was not enabled, otherwise true
*/
public boolean fire(Transition transition) {
boolean success;
lock.writeLock().lock();
try {
if (isEnabled(transition)) {
for (Arc arc : transition.getConnectedArcs()) {
if (arc.isPlaceToTransition()) {
int tokens = getTokens(arc.getPlaceNode());
if (!arc.getInhibitory()) { // inhibitory arc doesnt consume tokens
if (arc.getReset()) { // reset arc consumes them all
setTokens(arc.getPlaceNode(), 0);
} else {
setTokens(arc.getPlaceNode(), tokens - arc.getMultiplicity());
}
}
} else {
int tokens = getTokens(arc.getPlaceNode());
setTokens(arc.getPlaceNode(), tokens + arc.getMultiplicity());
}
}
success = true;
} else {
success = false;
}
} finally {
lock.writeLock().unlock();
}
return success;
}
/**
* Determines if a transition is enabled in this marking
*
* @param transition - transition to be checked
* @return true if transition is enabled in the marking, otherwise false
*/
public boolean isEnabled(Transition transition) {
boolean isEnabled = true;
lock.readLock().lock();
try {
for (Arc arc : transition.getConnectedArcs()) {
if (arc.isPlaceToTransition()) {
if (arc.getReset()) { // reset arc is always fireable
continue; // but can be blocked by other arcs
} else {
if (!arc.getInhibitory()) {
if (getTokens(arc.getPlaceNode()) < arc.getMultiplicity()) { // normal arc
isEnabled = false;
break;
}
} else {
if (getTokens(arc.getPlaceNode()) >= arc.getMultiplicity()) { // inhibitory arc
isEnabled = false;
break;
}
}
}
}
}
} finally {
lock.readLock().unlock();
}
return isEnabled;
}
public boolean canBeUnfired(Transition transition) {
boolean canBeUnfired = true;
lock.readLock().lock();
try {
for (Arc arc : transition.getConnectedArcs()) {
if (!arc.isPlaceToTransition()) {
if (getTokens(arc.getPlaceNode()) < arc.getMultiplicity()) {
canBeUnfired = false;
break;
}
}
}
} finally {
lock.readLock().unlock();
}
return canBeUnfired;
}
public void undoFire(Transition transition) {
lock.writeLock().lock();
try {
if (canBeUnfired(transition)) {
for (Arc arc : transition.getConnectedArcs()) {
if (!arc.isPlaceToTransition()) {
int tokens = getTokens(arc.getPlaceNode());
setTokens(arc.getPlaceNode(), tokens - arc.getMultiplicity());
} else {
int tokens = getTokens(arc.getPlaceNode());
setTokens(arc.getPlaceNode(), tokens + arc.getMultiplicity());
}
}
}
} finally {
lock.writeLock().unlock();
}
}
