ptolemy.domains.sr.lib
Class Pre

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.Pre

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 Pre
extends Transformer

When the input is present, the output is the previously received input. When the input is absent, the output is absent. The first time the input is present, the output is given by initialValue , or if initialValue is not given, then the output is absent. The output data type is greater than or equal to the input and the initialValue parameter, if it is given. Note that in contrast to the NonStrictDelay actor, this actor is strict. It cannot fire until the input is known. While NonStrictDelay delays by one clock tick, regardless of whether the input is present, this actor delays only present values, and produces an output only when the input is present.

Since:

Ptolemy II 4.1

Version:

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

Author:

Edward A. Lee

See Also:

NonStrictDelay, Serialized Form

Accepted Rating:

Red (cxh)

Proposed Rating:

Yellow (eal)

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

private Token	_currentToken
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

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

Method Summary

void	fire() If there is an input token, the produce the previously read input token on the output.
void	initialize() Initialize the actor by recording the value of initialValue, if there is one.
boolean	postfire() Update the state of the actor by recording the current input value, if there is one.
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, isStrict, 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, isStrict, 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. Can be of any type.

_currentToken

private Token _currentToken

Constructor Detail

Pre

public Pre(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

If there is an input token, the produce the previously read input token on the output. If there is no previously read input token, then produce the initialValue token. If the initialValue has not been set, the produce absent.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - Not thrown in this base class.

initialize

public void initialize()
                throws IllegalActionException

Initialize the actor by recording the value of initialValue, if there is one.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If there is no director.

postfire

public boolean postfire()
                 throws IllegalActionException

Update the state of the actor by recording the current input value, if there is one.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True if execution can continue into the next iteration.

Throws:

IllegalActionException - 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