/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package com.sun.corba.se.spi.orbutil.fsm ;

import java.util.Set ;

import java.util.HashSet ;

import com.sun.corba.se.spi.orbutil.fsm.Input ;

import com.sun.corba.se.spi.orbutil.fsm.StateEngine ;

import com.sun.corba.se.impl.orbutil.fsm.StateEngineImpl ;

import com.sun.corba.se.impl.orbutil.ORBUtility ;

import com.sun.corba.se.spi.orbutil.fsm.FSM ;

/**

 * 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

 */

public class FSMImpl implements FSM

{

    private boolean debug ;

    private State state ;

    private StateEngineImpl stateEngine ;

    /** Create an instance of an FSM using the StateEngine

    * in a particular start state.

    */

    public FSMImpl( StateEngine se, State startState )

    {

        this( se, startState, false ) ;

    }

    public FSMImpl( StateEngine se, State startState, boolean debug )

    {

        state = startState ;

        stateEngine = (StateEngineImpl)se ;

        this.debug = debug ;

    }

    /** Return the current state.

    */

    public State getState()

    {

        return state ;

    }

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

    * <p>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.

    * <ol>

    * <li>If a DEFERED result is returned, retry the input

    * <li>If a ENABLED result is returned, the action for the guarded action

    * is the current action

    * <li>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).

    * </ol>

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

    * <ol>

    * <li>If the next state is not the current state, execute the current state postAction method.

    * <li>Execute the action.

    * <li>If the next state is not the current state, execute the next state preAction method.

    * <li>Set the current state to the next state.

    * </ol>

    */

    public void doIt( Input in )

    {

        stateEngine.doIt( this, in, debug ) ;

    }

    // Methods for use only by StateEngineImpl

    public void internalSetState( State nextState )

    {

        if (debug) {

            ORBUtility.dprint( this, "Calling internalSetState with nextState = " +

                nextState ) ;

        }

        state = nextState ;

        if (debug) {

            ORBUtility.dprint( this, "Exiting internalSetState with state = " +

                state ) ;

        }

    }

}

// end of FSMImpl.java