org.glassfish.pfl.basic.fsm
Class StateEngine

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

public class StateEngine
extends Object

Encodes the state transition function for a finite state machine.

Author:

Ken Cavanaugh

Method Summary

StateEngine	add(State oldState, Input input, Action action, State newState) Add a transition with a guard that always evaluates to true.
StateEngine	add(State oldState, Input input, Guard guard, Action action, State newState) Add a new transition (old,in,guard,act,new) to the state engine.
StateEngine	add(State oldState, Set<Input> input, Action action, State newState) Repeatedly call add( State, Input, Action, State ) for each element of input.
StateEngine	add(State oldState, Set<Input> input, Guard guard, Action action, State newState) Repeatedly calls add( State, Input, Guard, Action, State ) for each element of input.
static StateEngine	create() Create an empty uninitialized state engine.
void	doIt(Runner runner, Input in, boolean debug) Actually perform a state transition on the FSM on the runner.peek() FSM under Input in.
void	done() Called after all transitions have been added to the state engine.
Set<State>	getStates(State.Kind kind) Return the set of final states for this state engine.
StateEngine	setDefault(State oldState) Euaivalent to setDefault( oldState, oldState )
StateEngine	setDefault(State oldState, Action action, State newState) Set the default transition and action for a state.
StateEngine	setDefault(State oldState, State newState) Equivalent to setDefault( oldState, act, newState ) where act is an action that does nothing.
void	setDefaultAction(Action act) Set the default action used in this state engine.

Methods inherited from class java.lang.Object

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

Method Detail

create

public static StateEngine create()

Create an empty uninitialized state engine.

getStates

public Set<State> getStates(State.Kind kind)

Return the set of final states for this state engine. This may be an empty set.

add

public StateEngine add(State oldState,
                       Input input,
                       Guard guard,
                       Action action,
                       State newState)

Add a new transition (old,in,guard,act,new) to the state engine. Multiple calls to add with the same old and in are permitted, in which case only a transition in which the guard evaluates to true will be taken. If no such transition is enabled, a default will be taken. If more than one transition is enabled, one will be chosen arbitrarily. This method can only be called before done(). An attempt to call it after done() results in an IllegalStateException.

add

public StateEngine add(State oldState,
                       Set<Input> input,
                       Guard guard,
                       Action action,
                       State newState)

Repeatedly calls add( State, Input, Guard, Action, State ) for each element of input.

add

public StateEngine add(State oldState,
                       Input input,
                       Action action,
                       State newState)

Add a transition with a guard that always evaluates to true.

add

public StateEngine add(State oldState,
                       Set<Input> input,
                       Action action,
                       State newState)

Repeatedly call add( State, Input, Action, State ) for each element of input.

setDefault

public StateEngine setDefault(State oldState,
                              Action action,
                              State newState)

Set the default transition and action for a state. This transition will be used if no more specific transition was defined for the actual input. Repeated calls to this method simply change the default. This method can only be called before done(). An attempt to call it after done() results in an IllegalStateException.

setDefault

public StateEngine setDefault(State oldState,
                              State newState)

Equivalent to setDefault( oldState, act, newState ) where act is an action that does nothing.

setDefault

public StateEngine setDefault(State oldState)

Euaivalent to setDefault( oldState, oldState )

done

public void done()

Called after all transitions have been added to the state engine. This provides an opportunity for the implementation to optimize its representation before the state engine is used. This method may only be called once. An attempt to call it more than once results in an IllegalStateException.

Note that a valid StateEngine must satisfy the following conditions:

1. It must contain exactly one state with Kind INITIAL.
2. No final state may have an outgoing transition.

If either of these conditions are violated, done() throws an IllegalStateException.

setDefaultAction

public void setDefaultAction(Action act)

Set the default action used in this state engine. This is the action that is called whenever there is no applicable transition. Normally this would simply flag an error. This method can only be called before done(). An attempt to call it after done() results in an IllegalStateException.

doIt

public void doIt(Runner runner,
                 Input in,
                 boolean debug)

Actually perform a state transition on the FSM on the runner.peek() FSM under Input in.