Package ptolemy.actor.util

Class PeriodicDirectorHelper

java.lang.Object

ptolemy.actor.util.PeriodicDirectorHelper

public class PeriodicDirectorHelper
extends java.lang.Object

This is a helper class for directors implementing PeriodicDirector. It collects common functionality to avoid code duplication.

Since:

Ptolemy II 8.0

Version:

$Id$

Author:

Edward A. Lee

See Also:

PeriodicDirector

Pt.AcceptedRating:

Red (eal)

Pt.ProposedRating:

Yellow (eal)

Constructor Summary

Constructors

Constructor	Description
PeriodicDirectorHelper(PeriodicDirector director)	Construct a new helper.

Method Summary

Modifier and Type	Method	Description
Time	fireAt(Actor actor, Time time)	Request a firing of the given actor at the given absolute time, and return the time at which the specified will be fired.
void	initialize()	If the period parameter is greater than zero, then request a first firing of the executive director, if there is one.
void	postfire()	If the period parameter is greater than 0.0, then if the associated director is at the top level, then increment its time by the specified period, and otherwise request a refiring at the current time plus the period.
boolean	prefire()	If the period value is greater than zero, then return true if the current time is a multiple of the value and the current microstep is 1.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PeriodicDirectorHelper

public PeriodicDirectorHelper(PeriodicDirector director)
                       throws IllegalActionException

Construct a new helper.

Parameters:

director - The associated director.

Throws:

IllegalActionException - If the argument is not an instance of Director.

Method Detail

fireAt

public Time fireAt(Actor actor,
                   Time time)
            throws IllegalActionException

Request a firing of the given actor at the given absolute time, and return the time at which the specified will be fired. If the period is 0.0 and there is no enclosing director, then this method returns the current time. If the period is 0.0 and there is an enclosing director, then this method delegates to the enclosing director, returning whatever it returns. If the period is not 0.0, then this method checks to see whether the requested time is equal to the current time plus an integer multiple of the period. If so, it returns the requested time. If not, it returns the earliest future time that exceeds the requested time.

Parameters:

actor - The actor scheduled to be fired.

time - The requested time.

Returns:

Either the requested time or the current time plus the period or whatever the enclosing director returns.

Throws:

IllegalActionException - If the operation is not permissible (e.g. the given time is in the past).

initialize

public void initialize()
                throws IllegalActionException

If the period parameter is greater than zero, then request a first firing of the executive director, if there is one.

Throws:

IllegalActionException - If the superclass throws it.

postfire

public void postfire()
              throws IllegalActionException

If the period parameter is greater than 0.0, then if the associated director is at the top level, then increment its time by the specified period, and otherwise request a refiring at the current time plus the period.

Throws:

IllegalActionException - If the period parameter cannot be evaluated.

prefire

public boolean prefire()
                throws IllegalActionException

If the period value is greater than zero, then return true if the current time is a multiple of the value and the current microstep is 1. The associated director expects to always be fired at microstep 1. If there is an enclosing director that does not understand superdense time, then we ignore that microstep and agree to fire anyway. This means simply that we will fire the first time that current time matches a multiple of the period.

Returns:

true If either the period has value 0.0 or the current time is a multiple of the period.

Throws:

IllegalActionException - If the period parameter cannot be evaluated.