/* A schedule element that contains a reference to an actor.
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*/
package ptolemy.actor.sched;
import java.util.Collections;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import ptolemy.actor.Actor;
import ptolemy.kernel.util.InvalidStateException;
//////////////////////////////////////////////////////////////////////////
//// Firing
/**
This class is a schedule element that contains a reference to an
actor and an iteration count. This class is used together
with the Schedule class to construct a static schedule.
This class is used to represent a single actor repeated some
number of times, whereas Schedule is used for multi-actor schedules.
The setActor() method is used to
create the reference to an actor, and the setIterationCount() method
to set the iteration count. The getActor() method will return
a reference to this actor, and getIterationCount() will return
the iteration count. <p>
It is more efficient to use this class than to simply maintain a list of
actors since actors will often fire multiple times consecutively. Using
this class (and the Schedule data structure in general) greatly reduces the
memory requirements of most large schedules.
@author Brian K. Vogel, Steve Neuendorffer
@version $Id$
@since Ptolemy II 1.0
@Pt.ProposedRating Green (vogel)
@Pt.AcceptedRating Yellow (chf)
@see ptolemy.actor.sched.Schedule
@see ptolemy.actor.sched.ScheduleElement
*/
public class Firing extends ScheduleElement {
/** Construct a firing with a default iteration count equal to one
* and with no parent schedule.
*/
public Firing() {
super();
}
/** Construct a firing with a actor, an iteration count equal to one
* and no parent schedule.
* @param actor The actor in the firing.
*/
public Firing(Actor actor) {
super();
_actor = actor;
}
///////////////////////////////////////////////////////////////////
//// public methods ////
/** Return the actor invocation sequence of the schedule in the
* form of a sequence of actors. For a valid schedule, all of the
* lowest-level nodes should be an instance of Actor. If the
* schedule is not valid, then the returned iterator will contain
* null elements.
* <p>
* A runtime exception is thrown if the
* underlying schedule structure is modified while the iterator
* is active.
*
* @return An iterator over a sequence of actors.
* @exception ConcurrentModificationException If the
* underlying schedule structure is modified while the iterator
* is active.
*/
public Iterator actorIterator() {
return new ActorIterator(getIterationCount());
}
/** Return the actor invocation sequence in the form
* of a sequence of firings.
* Since this ScheduleElement is a Firing, which
* represents an Actor and an iteration count. the
* iterator returned will contain exactly one Firing (this Firing).
* <p>
* A runtime exception is thrown if the
* underlying schedule structure is modified while the iterator
* is active.
*
* @return An iterator over a sequence of firings.
* @exception ConcurrentModificationException If the
* underlying schedule structure is modified while the iterator
* is active.
*/
public Iterator firingIterator() {
// FIXME: a ConcurrentModificationException will not necessarily
// be thrown, see the failing tests.
if (_firing == null) {
_firing = Collections.singletonList(this);
}
return _firing.iterator();
}
/** Get the actor associated with this Firing. The setActor()
* method is used to set the actor that this method returns.
* If setActor() was never called, then throw an exception.
*
* @return The actor associated with this Firing.
* @see #setActor(Actor)
*/
public Actor getActor() {
return _actor;
}
/** Set the actor associated with this firing. This actor will
* then be returned when the getActor() method is invoked. If this
* firing already contains a reference to an actor, then the
* reference will overwritten.
*
* @param actor The actor to associate with this firing.
* @see #getActor()
*/
public void setActor(Actor actor) {
_incrementVersion();
_actor = actor;
}
/**
* Output a string representation of this Firing.
*/
public String toString() {
String result = "Fire Actor " + _actor;
int iterationCount = getIterationCount();
if (iterationCount > 1) {
result += (" " + iterationCount + " times");
}
return result;
}
///////////////////////////////////////////////////////////////////
//// inner classes ////
/** An adapter class for iterating over the elements of this
* schedule. An exception is thrown if the schedule structure
* changes while this iterator is active.
*/
private class ActorIterator implements Iterator {
// As of 8/02, it seems like this inner class is not really
// used except by the test suite.
/** Construct a ScheduleIterator.
*/
public ActorIterator(int iterationCount) {
_startingVersion = _getVersion();
_currentElement = 0;
_iterationCount = iterationCount;
}
/** Return true if the iteration has more elements.
*
* @exception ConcurrentModificationException If the schedule
* data structure has changed since this iterator
* was created.
* @return true if the iterator has more elements.
*/
public boolean hasNext() {
if (_startingVersion != _getVersion()) {
throw new ConcurrentModificationException(
"Schedule structure changed while iterator is active.");
} else {
return (_currentElement <= _iterationCount);
}
}
/** Return the next object in the iteration.
*
* @exception InvalidStateException If the schedule
* data structure has changed since this iterator
* was created.
* @return the next object in the iteration.
*/
public Object next() throws NoSuchElementException {
if (!hasNext()) {
throw new NoSuchElementException("No element to return.");
} else {
_currentElement++;
return getActor();
}
}
/** Throw an exception, since removal is not allowed. It really
* doesn't make sense to remove an actor from an actor invocation
* sequence anyway.
*/
public void remove() {
throw new UnsupportedOperationException();
}
private long _startingVersion;
private int _currentElement;
private int _iterationCount;
}
///////////////////////////////////////////////////////////////////
//// private variables ////
// The actor associated with this firing.
private Actor _actor;
// The list containing this firing as the only element.
private List _firing = null;
}