ptolemy.domains.sr.lib
Class NonStrictDelay

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.actor.lib.Transformer
                              ptolemy.domains.sr.lib.NonStrictDelay

All Implemented Interfaces:

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

public class NonStrictDelay
extends Transformer

A nonstrict actor that delays tokens by one iteration.

This actor provides a one-tick delay. On each firing, it produces on the output port whatever value it read on the input port in the previous tick of the clock. If the input was absent on the previous tick of the clock, then the output will be absent. On the first tick, the output is initialValue if it is given, and absent otherwise. In contrast to the Pre actor, this actor is non-strict, and hence can break causality loops. Whereas Pre provides a one-step delay of non-absent values, this actor simply delays by one clock tick.

Since:

Ptolemy II 2.0

Version:

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

Author:

Paul Whitaker, Elaine Cheong, and Edward A. Lee

See Also:

Pre, SampleDelay, TimedDelay, Serialized Form

Accepted Rating:

Yellow (cxh)

Proposed Rating:

Yellow (celaine)

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

protected Token	_previousToken The token received on the previous iteration to be output on the current iteration.
Parameter	initialValue Initial token value.

Fields inherited from class ptolemy.actor.lib.Transformer

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

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

Method Summary

void	fire() Send to the output the previous token received.
void	initialize() Initialize the state of the actor.
boolean	isStrict() Return false.
boolean	postfire() If the input is known, then read it and record it for the next tick.
void	preinitialize() Override the base class to declare that the output does not depend on the input in a firing.
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.

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, iterate, newReceiver, outputPortList, prefire, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup

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, iterate, prefire, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, removeInitializable, wrapup

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

Initial token value. This defaults to no value, which results in the first output being absent. If a value is given, then output will be constrained to have at least the type of the value (as well as at least the type of the input).

_previousToken

protected Token _previousToken

The token received on the previous iteration to be output on the current iteration.

Constructor Detail

NonStrictDelay

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

Construct an actor in the specified container with the specified name.

Parameters:

container - The container.

name - The name of this actor within the container.

Throws:

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

NameDuplicationException - If the name coincides with an actor already in the container.

Method Detail

fire

public void fire()
          throws IllegalActionException

Send to the output the previous token received. If no token was received on the previous tick, then assert that the output is absent. If this is the first tick, then produce on the output the value provided by initialValue, or there was none, then assert that the output is empty.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If there is no director.

initialize

public void initialize()
                throws IllegalActionException

Initialize the state of the actor.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If there is no director.

isStrict

public boolean isStrict()

Return false. This actor can produce some output event the input receiver has status unknown.

Specified by:

isStrict in interface Executable

Overrides:

isStrict in class AtomicActor

Returns:

False.

postfire

public boolean postfire()
                 throws IllegalActionException

If the input is known, then read it and record it for the next tick. Otherwise, throw an exception.

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 input is not known, or if there is no director.

preinitialize

public void preinitialize()
                   throws IllegalActionException

Override the base class to declare that the output does not depend on the input in a firing.

Specified by:

preinitialize in interface Initializable

Overrides:

preinitialize in class AtomicActor

Throws:

IllegalActionException - If the superclass 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