org.glassfish.pfl.basic.fsm
Class Runner

java.lang.Object
  org.glassfish.pfl.basic.fsm.Runner

public class Runner
extends Object

This is the main class that represents an instance of a state machine using a state engine. It may be used as a base class, in which case the guards and actions have access to the derived class.

Author:

Ken Cavanaugh

Constructor Summary

Runner(FSM fsm)
Create a new Runner with fsm on top of the stack.

Runner(FSM fsm, boolean debug)

Method Summary

void	doIt(Input in) Perform the transition for the given input in the current state.
boolean	done() Return true if the stack is empty, which means that the runner is finished.
FSM	peek() Return the top fsm on the stack.
FSM	pop()
void	push(FSM fsm) Push a new fsm onto the stack.

Methods inherited from class java.lang.Object

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

Constructor Detail

Runner

public Runner(FSM fsm)

Create a new Runner with fsm on top of the stack.

Runner

public Runner(FSM fsm,
              boolean debug)

Method Detail

peek

public FSM peek()

Return the top fsm on the stack.

push

public void push(FSM fsm)

Push a new fsm onto the stack.

pop

public FSM pop()

done

public boolean done()

Return true if the stack is empty, which means that the runner is finished.

doIt

public void doIt(Input in)

Perform the transition for the given input in the current state. This proceeds as follows:

Let S be the current state of the FSM. If there are guarded actions for S with input in, evaluate their guards successively until all have been evaluted, or one returns a non-DISABLED Result.

1. If a DEFERED result is returned, retry the input
2. If a ENABLED result is returned, the action for the guarded action is the current action
3. Otherwise there is no enabled action. If S has a default action and next state, use them; otherwise use the state engine default action (the next state is always the current state).

After the action is available, the transition proceeds as follows:

1. If the next state is not the current state, execute the current state postAction method.
2. Execute the action.
3. If the next state is not the current state, execute the next state preAction method.
4. Set the current state to the next state.