/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.glassfish.pfl.basic.fsm ;

An FSM is used to represent an instance of a finite state machine
which has a transition function represented by an instance of
StateEngine.  An instance of an FSM may be created either by calling
StateEngine.makeFSM( startState ) on a state engine, or by extending FSMImpl and
using a constructor.  Using FSMImpl as a base class is convenient if
additional state is associated with the FSM beyond that encoded 
by the current state.  This is especially convenient if an action
needs some additional information.  For example, counters are best
handled by special actions rather than encoding a bounded counter
in a state machine.  It is also possible to create a class that
implements the FSM interface by delegating to an FSM instance
created by StateEngine.makeFSM.
Author:
Ken Cavanaugh/**
 * An FSM is used to represent an instance of a finite state machine
 * which has a transition function represented by an instance of
 * StateEngine.  An instance of an FSM may be created either by calling
 * StateEngine.makeFSM( startState ) on a state engine, or by extending FSMImpl and
 * using a constructor.  Using FSMImpl as a base class is convenient if
 * additional state is associated with the FSM beyond that encoded 
 * by the current state.  This is especially convenient if an action
 * needs some additional information.  For example, counters are best
 * handled by special actions rather than encoding a bounded counter
 * in a state machine.  It is also possible to create a class that
 * implements the FSM interface by delegating to an FSM instance
 * created by StateEngine.makeFSM.
 *
 * @author Ken Cavanaugh
 */
public interface FSM
{
    
Return the state engine used to create this FSM.
/** Return the state engine used to create this FSM.
     */
    public StateEngine getStateEngine() ;

    
Get the parent state machine.
/** Get the parent state machine.
     */
    public FSM getParent() ;

    
Set the parent state machine.
/** Set the parent state machine.
     */
    public void setParent( FSM fsm ) ;

    
Set the current state of this FSM.  May not be called
inside a transition action, or from a State method.
Only here for use by the StateEngine.
/** Set the current state of this FSM.  May not be called
     * inside a transition action, or from a State method.
     * Only here for use by the StateEngine.
     */
    public void setState( State state ) ;

    
Get the current state of this FSM.
/** Get the current state of this FSM.
    */
    public State getState() ;
}

// end of FSM.java