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/*
* @(#)TransitionImpl.java
*
* Copyright (C) 2002-2003 Matt Albrecht
* groboclown@users.sourceforge.net
* http://groboutils.sourceforge.net
*
* Part of the GroboUtils package at:
* http://groboutils.sourceforge.net
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
package net.sourceforge.groboutils.mbtf.v1.engine;
import net.sourceforge.groboutils.mbtf.v1.IState;
import net.sourceforge.groboutils.mbtf.v1.IAction;
import net.sourceforge.groboutils.mbtf.v1.IValidate;
import net.sourceforge.groboutils.mbtf.v1.ITransition;
/**
* Nearly-Immutable implementation of ITransition. As an immutable, transitions
* cannot be created if there are cycles in the state machine. Therefore,
* there needs to be a way to post-creation correctly populate the Transition's
* destination state. Thus, the destination state may be set once.
*
* @author Matt Albrecht <a href="mailto:groboclown@users.sourceforge.net">groboclown@users.sourceforge.net</a>
* @version $Date: 2003/02/10 22:52:26 $
* @since June 12, 2002
*/
public class TransitionImpl implements ITransition
{
private String name;
private IState destination;
private IAction action;
private IValidate[] validate;
public TransitionImpl( String name, IState dest, IAction a, IValidate[] v )
{
// allow destination to be null
if (name == null || a == null)
{
throw new IllegalArgumentException("no null args");
}
if (v == null)
{
v = new IValidate[0];
}
else
{
int len = v.length;
IValidate[] vv = new IValidate[ len ];
for (int i = len; --i >= 0;)
{
if (v[i] == null)
{
throw new IllegalArgumentException(
"no nulls allowed in IValidate array");
}
// else
vv[i] = v[i];
}
v = vv;
}
this.name = name;
setDestinationState( dest );
this.action = a;
this.validate = v;
}
/**
* Retrieves the name for the transition. This should be unique for
* state-machine assembly purposes, but it does not have to be.
*
* @return a non-null name for this transition.
*/
public String getName()
{
return this.name;
}
/**
* Returns the next state if the corresponding action is executed.
*
* @return destination state, which can never be <tt>null</tt>.
*/
public IState getDestinationState()
{
if (isDestinationStateSet())
{
return this.destination;
}
// else
throw new IllegalStateException("Destination was never set.");
}
/**
* Returns the action used to transition to the destination state.
*
* @return transition's action, which can never be <tt>null</tt>.
*/
public IAction getAction()
{
return this.action;
}
/**
* Returns all validation methods used to assert that the system can
* perform this transition.
*
* @return a list of associated validation instances.
*/
public IValidate[] getValidates()
{
int len = this.validate.length;
IValidate v[] = new IValidate[ len ];
System.arraycopy( this.validate, 0, v, 0, len );
return v;
}
//-------------------------------------------------------------------------
/**
* Allows for post-creation setting of the destination. The destination
* may only be set to a non-<tt>null</tt> value once. If there is an
* attempt to pull the destination through <tt>getDestinationState()</tt>
* and it has not been set yet, then an IllegalStateException will
* be thrown.
*/
public void setDestinationState( IState dest )
{
if (isDestinationStateSet())
{
throw new IllegalStateException(
"Destination has already been set.");
}
else
{
this.destination = dest;
}
}
/**
* Allows for a builder system to detect if the destination state has
* been set or not, without causing the IllegalStateException through
* the <tt>getDestinationState()</tt>.
*/
public boolean isDestinationStateSet()
{
return (this.destination != null);
}
public String toString()
{
return "[Transition "+getName()+"]";
}
}
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