public class Expression extends TypedAtomicActor
On each firing, evaluate an expression that may include references to the inputs, current time, and a count of the firing. The ports are referenced by the identifiers that have the same name as the port. To use this class, instantiate it, then add ports (instances of TypedIOPort). In vergil, you can add ports by right clicking on the icon and selecting "Configure Ports". In MoML you can add ports by just including ports of class TypedIOPort, set to be inputs, as in the following example:
<entity name="exp" class="ptolemy.actor.lib.Expression"> <port name="in" class="ptolemy.actor.TypedIOPort"> <property name="input"/> </port> </entity>
This actor is type-polymorphic. The types of the inputs can be arbitrary and the types of the outputs are inferred from the expression based on the types inferred for the inputs.
The expression parameter specifies an expression that can refer to the inputs by name. By default, the expression is empty, and attempting to execute the actor without setting it triggers an exception. This actor can be used instead of many of the arithmetic actors, such as AddSubtract, MultiplyDivide, and TrigFunction. However, those actors will be usually be more efficient, and sometimes more convenient to use.
The expression language understood by this actor is the same as that used to set any parameter value, with the exception that the expressions evaluated by this actor can refer to the values of inputs, and to the current time by the identifier name "time", and to the current iteration count by the identifier named "iteration."
This actor requires its all of its inputs to be present. If inputs are not all present, then an exception will be thrown.
NOTE: There are a number of limitations in the current implementation. Primarily, multiports are not supported.
| Green (neuendor) |
| Green (neuendor) |
Entity.ContainedObjectsIterator| Modifier and Type | Field and Description |
|---|---|
protected Token |
_result
Variable storing the result of the expression evaluation so that
subclasses can access it in an overridden fire() method.
|
protected java.util.Map<java.lang.String,Token> |
_tokenMap
Map from input port name to input value.
|
StringAttribute |
expression
The expression that is evaluated to produce the output.
|
TypedIOPort |
output
The output port.
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_typesValid_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _deferChangeRequests, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKSCOMPLETED, NOT_READY, STOP_ITERATING| Constructor and Description |
|---|
Expression(CompositeEntity container,
java.lang.String name)
Construct an actor with the given container and name.
|
| Modifier and Type | Method and Description |
|---|---|
void |
attributeChanged(Attribute attribute)
React to a change in the value of an attribute.
|
java.lang.Object |
clone(Workspace workspace)
Clone the actor into the specified workspace.
|
void |
fire()
Evaluate the expression and send its result to the output.
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void |
initialize()
Initialize the iteration count to 1.
|
boolean |
postfire()
Increment the iteration count.
|
boolean |
prefire()
Prefire this actor.
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void |
preinitialize()
Preinitialize this actor.
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_containedTypeConstraints, _customTypeConstraints, _defaultTypeConstraints, _fireAt, _fireAt, attributeTypeChanged, clone, isBackwardTypeInferenceEnabled, newPort, typeConstraintList, typeConstraints_actorFiring, _actorFiring, _declareDelayDependency, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName_addPort, _description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _containedDecorators, _copyChangeRequestList, _debug, _debug, _debug, _debug, _debug, _executeChangeRequests, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _notifyHierarchyListenersAfterChange, _notifyHierarchyListenersBeforeChange, _propagateValue, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, addHierarchyListener, 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, workspaceequals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitcreateReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortListisFireFunctional, isStrict, iterate, stop, stopFire, terminateaddInitializable, removeInitializable, wrapupdescription, getContainer, getDisplayName, getFullName, getName, getName, setNamegetDerivedLevel, getDerivedList, propagateValuepublic TypedIOPort output
public StringAttribute expression
protected Token _result
protected java.util.Map<java.lang.String,Token> _tokenMap
public Expression(CompositeEntity container, java.lang.String name) throws NameDuplicationException, IllegalActionException
container - The container.name - The name of this actor.IllegalActionException - If the actor cannot be contained
by the proposed container.NameDuplicationException - If the container already has an
actor with this name.public void attributeChanged(Attribute attribute) throws IllegalActionException
attributeChanged in class NamedObjattribute - The attribute whose type changed.IllegalActionException - Not thrown in this base class.public java.lang.Object clone(Workspace workspace) throws java.lang.CloneNotSupportedException
clone in class TypedAtomicActorworkspace - The workspace for the new object.java.lang.CloneNotSupportedException - If a derived class contains
an attribute that cannot be cloned.NamedObj.exportMoML(Writer, int, String),
NamedObj.setDeferringChangeRequests(boolean)public void fire()
throws IllegalActionException
fire in interface Executablefire in class AtomicActor<TypedIOPort>IllegalActionException - If the evaluation of the expression
triggers it, or the evaluation yields a null result, or the evaluation
yields an incompatible type, or if there is no director, or if a
connected input has no tokens.public void initialize()
throws IllegalActionException
initialize in interface Initializableinitialize in class AtomicActor<TypedIOPort>IllegalActionException - If the parent class throws it.public boolean postfire()
throws IllegalActionException
postfire in interface Executablepostfire in class AtomicActor<TypedIOPort>IllegalActionException - If the superclass throws it.public boolean prefire()
throws IllegalActionException
prefire in interface Executableprefire in class AtomicActor<TypedIOPort>IllegalActionException - If the superclass throws it.public void preinitialize()
throws IllegalActionException
preinitialize in interface Initializablepreinitialize in class AtomicActor<TypedIOPort>IllegalActionException - Not thrown in this base class.