Package ptolemy.caltrop.ddi.util

Class DataflowActorInterpreter

java.lang.Object

ptolemy.caltrop.ddi.util.DataflowActorInterpreter

Direct Known Subclasses:

DataflowWithRatesActorInterpreter

public class DataflowActorInterpreter
extends java.lang.Object

The actor interpreter provides an abstract interface to the execution of an actor. It provides a number of operations on the actions of an actor, allowing clients to test them for firability and execute them.

An instance of this class maintains some internal state identifying the action it currently works on. It expects its methods to be called in a particular order, viz.
actionSetup(action) -- actionEvaluatePrecondition() -- actionStep() -- actionComputeOutputs()
During such a sequence, the methods operate on action n, which was selected by the call to actionSetup(action). At any point in time, the client may call actionClear(), which deselects the action and deletes the references to the resources used by the action environment created during setup.

Since:

Ptolemy II 4.0

Version:

$Id$

Author:

Jörn W. Janneck

See Also:

Actor, Action, actionSetup(caltrop.interpreter.ast.Action), actionEvaluatePrecondition(), actionStep(), actionComputeOutputs(), actionClear()

Pt.AcceptedRating:

Red (cxh)

Pt.ProposedRating:

Red (cxh)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	DataflowActorInterpreter.EnvironmentKey
protected static class	DataflowActorInterpreter.MultipleTokenReaderThunk
protected static class	DataflowActorInterpreter.SingleTokenReaderThunk	A single token reader thunk encapsulates the operation of reading a single token from a specified channel.

Field Summary

Fields

Modifier and Type	Field	Description
protected caltrop.interpreter.ast.Actor	actor
protected caltrop.interpreter.environment.Environment	actorEnv
protected caltrop.interpreter.Context	context
protected caltrop.interpreter.environment.Environment	env
protected caltrop.interpreter.ast.Action	envAction
protected java.util.Map	inputPortMap

Constructor Summary

Constructors

Constructor	Description
DataflowActorInterpreter(caltrop.interpreter.ast.Actor actor, caltrop.interpreter.Context context, caltrop.interpreter.environment.Environment actorEnv, java.util.Map inputPortMap, java.util.Map outputPortMap)	Defines a new actor interpreter for the specified actor.

Method Summary

Modifier and Type	Method	Description
void	actionClear()	Clear action selection.
void	actionComputeOutputs()	Compute the output tokens and send them to the specified (at construction time) output channels.
boolean	actionEvaluatePrecondition()	Evaluate the preconditions for the action and return its result.
void	actionSetup(caltrop.interpreter.ast.Action action)	Set up the local environment of the specified action.
void	actionStep()	Execute the action body, potentially changing the value of actor state variables and action-scope variables.
caltrop.interpreter.ast.Action	currentAction()	Return the current action.
int	nActions()	Return the number of actions in this actor.
int	nInitializers()	Return the number of initializers in this actor.
void	setOutputPortMap(java.util.Map outputPortMap)

Methods inherited from class java.lang.Object

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

Field Detail

actor

protected caltrop.interpreter.ast.Actor actor

context

protected caltrop.interpreter.Context context

actorEnv

protected caltrop.interpreter.environment.Environment actorEnv

env

protected caltrop.interpreter.environment.Environment env

envAction

protected caltrop.interpreter.ast.Action envAction

inputPortMap

protected java.util.Map inputPortMap

Constructor Detail

DataflowActorInterpreter

public DataflowActorInterpreter(caltrop.interpreter.ast.Actor actor,
                                caltrop.interpreter.Context context,
                                caltrop.interpreter.environment.Environment actorEnv,
                                java.util.Map inputPortMap,
                                java.util.Map outputPortMap)

Defines a new actor interpreter for the specified actor.

Parameters:

actor - The actor.

context - The interpretation context.

actorEnv - The global environment.

inputPortMap - Map from input port names to channels.

outputPortMap - Map from output port names to channels.

See Also:

InputChannel, OutputChannel

Method Detail

actionSetup

public void actionSetup(caltrop.interpreter.ast.Action action)

Set up the local environment of the specified action. This method is the only way a new action may be set up for execution. If completed successfully, the action environment and the action are stored in the state of this interpreter, and other methods may operate on them.

Parameters:

action - The action to setup.

actionEvaluatePrecondition

public boolean actionEvaluatePrecondition()

Evaluate the preconditions for the action and return its result. If this method returns false, some condition required for the successful completion of the action is not satisfied. This might be an insufficient number of input tokens, or some other condition depending on the value of the tokens or state variables.

Note that the converse need not hold---depending on the model of computation, a true return value does not necessarily imply that the action will successfully execute. It may represent an approximation to a complete precondition, in which case the model of computation is not responsible.

Returns:

True, if the action precondition was satisfied.

Throws:

caltrop.interpreter.InterpreterException - If the evaluation of the guards could not be successfully completed.

actionStep

public void actionStep()

Execute the action body, potentially changing the value of actor state variables and action-scope variables.

Throws:

caltrop.interpreter.InterpreterException - If the action body could not be executed successfully.

actionComputeOutputs

public void actionComputeOutputs()

Compute the output tokens and send them to the specified (at construction time) output channels.

See Also:

DataflowActorInterpreter

actionClear

public void actionClear()

Clear action selection. The reference to the environment is cleared, too, allowing the system to reclaim any resources associated with it.

currentAction

public caltrop.interpreter.ast.Action currentAction()

Return the current action. This is null if none has been selected.

Returns:

The current action, null if none.

nActions

public int nActions()

Return the number of actions in this actor.

Returns:

Number of actions.

nInitializers

public int nInitializers()

Return the number of initializers in this actor.

Returns:

Number of initializers.

setOutputPortMap

public void setOutputPortMap(java.util.Map outputPortMap)