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/***************************************************************************
* Copyright (c) 2004, 2005, 2006 Eike Stepper, Fuggerstr. 39, 10777 Berlin, Germany.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Eike Stepper - initial API and implementation
**************************************************************************/
package org.eclipse.net4j.util.fsm;
import org.apache.log4j.Logger;
public abstract class StateMachine<SUBJECT> implements IStateMachine<SUBJECT>
{
private static final Logger logger = Logger.getLogger(StateMachine.class.getName());
private String[] stateNames;
private String[] eventNames;
private ITransition<SUBJECT>[][] matrix;
public StateMachine(String[] stateNames, String[] eventNames,
ITransition<SUBJECT> defaultTransition)
{
this.stateNames = stateNames;
this.eventNames = eventNames;
matrix = new ITransition[stateNames.length][eventNames.length];
if (defaultTransition != null)
{
for (int state = 0; state < stateNames.length; state++)
{
for (int event = 0; event < eventNames.length; event++)
{
handle(state, event, defaultTransition);
}
}
}
}
public StateMachine(String[] stateNames, String[] eventNames)
{
this(stateNames, eventNames, null);
}
public int getStateCount()
{
return stateNames.length;
}
public int getEventCount()
{
return eventNames.length;
}
public String getStateName(int state)
{
return stateNames[state];
}
public String getEventName(int event)
{
return eventNames[event];
}
public ITransition<SUBJECT> getIdentityTransition()
{
return new ITransition<SUBJECT>()
{
public void process(SUBJECT subject, int event, Object data) throws Exception
{
if (getLogger().isDebugEnabled())
{
int state = getState(subject);
getLogger().debug("Ignoring " + makeLabel(subject, state, event));
}
}
};
}
public void handle(int state, int event, ITransition<SUBJECT> transition)
{
matrix[state][event] = transition;
}
public void handle(int state, int event, final int newState)
{
handle(state, event, new ITransition<SUBJECT>()
{
public void process(SUBJECT subject, int event, Object data) throws Exception
{
setState(subject, newState);
}
});
}
public void ignore(int state, int event)
{
handle(state, event, getIdentityTransition());
}
public void cancel(int state, int event)
{
handle(state, event, null);
}
public void process(SUBJECT subject, int event, Object data) throws Exception
{
int state = getState(subject);
ITransition<SUBJECT> transition = matrix[state][event];
if (transition == null)
{
if (getLogger().isDebugEnabled())
{
getLogger().warn("Ignoring " + makeLabel(subject, state, event));
}
return;
}
if (getLogger().isDebugEnabled())
{
getLogger().debug("Processing " + makeLabel(subject, state, event));
}
transition.process(subject, event, data);
if (getLogger().isDebugEnabled())
{
int newState = getState(subject);
getLogger()
.debug(
"Finished " + makeLabel(subject, state, event) + ", newState="
+ getStateName(newState));
}
}
protected Logger getLogger()
{
return logger;
}
protected String makeLabel(SUBJECT subject, int state, int event)
{
return "event " + eventNames[event] + " in state " + stateNames[state] + " for subject "
+ subject;
}
protected abstract int getState(SUBJECT subject);
protected abstract void setState(SUBJECT subject, int state);
}
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