Package ptolemy.domains.sr.lib

Class Pre

java.lang.Object

ptolemy.kernel.util.NamedObj

ptolemy.kernel.InstantiableNamedObj

ptolemy.kernel.Entity<T>

ptolemy.kernel.ComponentEntity<T>

ptolemy.actor.AtomicActor<TypedIOPort>

ptolemy.actor.TypedAtomicActor

ptolemy.actor.lib.Transformer

ptolemy.domains.sr.lib.Pre

All Implemented Interfaces:

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:

$Id$

Author:

Edward A. Lee

See Also:

NonStrictDelay

Pt.AcceptedRating:

Red (cxh)

Pt.ProposedRating:

Yellow (eal)

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

Fields

Modifier and Type	Field	Description
Parameter	initialValue	Initial token value.

Fields inherited from class ptolemy.actor.lib.Transformer

input, output

Fields inherited from class ptolemy.actor.TypedAtomicActor

_typesValid

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _deferChangeRequests, _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

Constructors

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

Method Summary

Modifier and Type	Method	Description
protected java.util.Set<Inequality>	_customTypeConstraints()	Return a constraint that requires the initial value to be less than or equal to the type of the output.
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.

Methods inherited from class ptolemy.actor.TypedAtomicActor

_containedTypeConstraints, _defaultTypeConstraints, _fireAt, _fireAt, attributeTypeChanged, clone, clone, isBackwardTypeInferenceEnabled, newPort, typeConstraintList, typeConstraints

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, _declareDelayDependency, addActorFiringListener, addInitializable, 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

_addPort, _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, _containedDecorators, _copyChangeRequestList, _debug, _debug, _debug, _debug, _debug, _executeChangeRequests, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _notifyHierarchyListenersAfterChange, _notifyHierarchyListenersBeforeChange, _propagateValue, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, addHierarchyListener, attributeChanged, attributeDeleted, attributeList, attributeList, decorators, 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, notifyOfNameChange, propagateValue, propagateValues, removeAttribute, removeChangeListener, removeDebugListener, removeHierarchyListener, 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.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

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

Field Detail

initialValue

public Parameter initialValue

Initial token value. Can be of any type.

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<TypedIOPort>

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<TypedIOPort>

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<TypedIOPort>

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<TypedIOPort>

Throws:

IllegalActionException - If the superclass throws it.

_customTypeConstraints

protected java.util.Set<Inequality> _customTypeConstraints()

Return a constraint that requires the initial value to be less than or equal to the type of the output.

Overrides:

_customTypeConstraints in class TypedAtomicActor

Returns:

null