sequence.java

Rakiura JFern是一个非常轻型的带有模拟器的Petri网络框架

// This is copyrighted source file, part of Rakiura JFern package. 
// See the file LICENSE for copyright information and the terms and conditions
// for copying, distributing and modifications of Rakiura JFern package.
// Copyright (C) 1999-2002 by Mariusz Nowostawski and others  [http://www.rakiura.org]

package org.rakiura.cpn.lib;

/**/
import java.util.ArrayList;
import java.util.List;

import org.rakiura.cpn.InputArc;
import org.rakiura.cpn.Multiset;
import org.rakiura.cpn.OutputArc;
import org.rakiura.cpn.Place;
import org.rakiura.cpn.Transition;


/**
 * Simple control pattern representing Sequence Pattern. This pattern
 * net begins with the input place, which makes the first transition
 * enabled, and ends with transition n-th, which puts the processed
 * token into the final output place. All intermediate places and arcs 
 * are not visible to the user, they simply propagate single token at
 * the time. This sequence does not wait till the token is passed till
 * the end of the sequence, and can fire another sequence once the
 * input place has at least one token (first transition is enabled).
 * 
 *<br><br>
 * SequenceTT.java<br>
 * Created: Tue Oct  3 09:21:20 2000<br>
 *
 * @author Mariusz Nowostawski
 * @version 2.1.0 $Revision: 1.6 $
 */
public class Sequence extends PatternPT {

  protected Place outputPlace;
  protected OutputArc outputArc;
  protected List transitionList;


  /** @todo write comments. */
  public Sequence() {
    
    final Transition trans2 = new Transition();
    transitionList = new ArrayList(10);
    transitionList.add(transition);
    transitionList.add(trans2);

    final Place tmpPlace = new Place();
    createOutputArc(transition, tmpPlace);
    createInputArc(tmpPlace, trans2);

    outputPlace = new Place();
    createOutputArc(trans2, outputPlace);

    add(tmpPlace).add(trans2).add(outputPlace);
  }

  public List transitions(){
    return this.transitionList;
  }

  public Place inputPlace(){
    return this.inputPlace;
  }

  public Place outputPlace(){
    return this.outputPlace;
  }

  private InputArc createInputArc(Place p, Transition t) {
    final InputArc arc = new InputArc(p, t);
    arc.setGuard(arc.new Guard() {
        public boolean evaluate() {
          final Multiset multiset = getMultiset();
          return (multiset.size()>0);
        }        
      });
    arc.setExpression(arc.new Expression() {
        public void evaluate() {
          var("X");
        }       
      });
    return arc;
  }

  
  private OutputArc createOutputArc(Transition t, Place p){
    final OutputArc arc = new OutputArc(t, p);
    arc.setExpression(arc.new Expression() {
        public Multiset evaluate() {
          final Multiset multiset = getMultiset();
          final Multiset result = new Multiset();
          result.add(multiset.getAny());
          return result;
        }
      });
    return arc;
  }
  

} // Sequence
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