ptolemy.domains.de.lib
Class Previous

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.domains.de.kernel.DEActor
                              ptolemy.domains.de.lib.DETransformer
                                  ptolemy.domains.de.lib.Previous

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, SequenceActor, TimedActor, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

public class Previous
extends DETransformer

On each iteration, this actor produces the token received on the previous iteration. On the first iteration, it produces the token given by the initialValue parameter, if such a value has been set.

Although it might be tempting to try, this actor is not very useful for breaking precedences in a feedback loop in DE, the way the TimedDelay actor in DE or the SampleDelay actor in SDF do. Since it does not trigger until there is an input, it will not actually break the precedences in a feedback loop.

The output data type is constrained to be at least as general as both the input and the initialValue parameter.

Since:

Ptolemy II 2.0

Version:

$Id: Previous.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Edward A. Lee

See Also:

TimedDelay, SampleDelay, Serialized Form

Accepted Rating:

Red (cxh)

Proposed Rating:

Red (eal)

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.kernel.Entity

Entity.ContainedObjectsIterator

Field Summary

private Token	_previous
private Token	_tempPrevious
Parameter	initialValue The initial output value.

Fields inherited from class ptolemy.domains.de.lib.DETransformer

input, output

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS

Fields inherited from interface ptolemy.actor.Executable

COMPLETED, NOT_READY, STOP_ITERATING

Constructor Summary

Previous(CompositeEntity container, java.lang.String name)
Construct an actor with the specified container and name.

Method Summary

void	fire() If there is a previous token, then produce it on the output, and then read the input and record it for the next firing.
void	initialize() Initialize so that the initial token will be produced.
boolean	postfire() Update the state of the actor.
java.util.Set<Inequality>	typeConstraints() Override the method in the base class so that the type constraint for the initialValue parameter will be set if it contains a value.
void	wrapup() Reset the state variables.

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, _fireAt, _fireAt, attributeTypeChanged, clone, newPort, typeConstraintList

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, addActorFiringListener, addInitializable, clone, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, prefire, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate

Methods inherited from class ptolemy.kernel.ComponentEntity

_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName

Methods inherited from class ptolemy.kernel.Entity

_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName

Methods inherited from class ptolemy.kernel.InstantiableNamedObj

_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeChanged, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace

Methods inherited from class java.lang.Object

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

Methods inherited from interface ptolemy.actor.Actor

createReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortList

Methods inherited from interface ptolemy.actor.Executable

isFireFunctional, isStrict, iterate, prefire, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable

Methods inherited from interface ptolemy.kernel.util.Nameable

description, getContainer, getDisplayName, getFullName, getName, getName, setName

Methods inherited from interface ptolemy.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

Field Detail

initialValue

public Parameter initialValue

The initial output value. If this is set, it specifies the first output value produced when the first input arrives. If it is not set, then no output is produced on the first firing.

_previous

private Token _previous

_tempPrevious

private Token _tempPrevious

Constructor Detail

Previous

public Previous(CompositeEntity container,
                java.lang.String name)
         throws NameDuplicationException,
                IllegalActionException

Construct an actor with the specified container and name.

Parameters:

container - The composite actor to contain this one.

name - The name of this actor.

Throws:

IllegalActionException - If the entity cannot be contained by the proposed container.

NameDuplicationException - If the container already has an actor with this name.

Method Detail

fire

public void fire()
          throws IllegalActionException

If there is a previous token, then produce it on the output, and then read the input and record it for the next firing.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If getting token from input or sending token to output throws it.

initialize

public void initialize()
                throws IllegalActionException

Initialize so that the initial token will be produced.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If the super class throws it or can not get a valid token from the initializeValue parameter.

postfire

public boolean postfire()
                 throws IllegalActionException

Update the state of the actor.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True if execution can continue into the next iteration.

Throws:

IllegalActionException - If the base class throws it.

typeConstraints

public java.util.Set<Inequality> typeConstraints()

Override the method in the base class so that the type constraint for the initialValue parameter will be set if it contains a value.

Specified by:

typeConstraints in interface TypedActor

Overrides:

typeConstraints in class TypedAtomicActor

Returns:

a list of Inequality objects.

See Also:

Inequality

wrapup

public void wrapup()
            throws IllegalActionException

Reset the state variables.

Specified by:

wrapup in interface Initializable

Overrides:

wrapup in class AtomicActor

Throws:

IllegalActionException - If the base class throws it.