SearchListenerMulticaster.java :  » Code-Analyzer » javapathfinder » gov » nasa » jpf » Java Open Source

//
// Copyright (C) 2005 United States Government as represented by the
// Administrator of the National Aeronautics and Space Administration
// (NASA).  All Rights Reserved.
// 
// This software is distributed under the NASA Open Source Agreement
// (NOSA), version 1.3.  The NOSA has been approved by the Open Source
// Initiative.  See the file NOSA-1.3-JPF at the top of the distribution
// directory tree for the complete NOSA document.
// 
// THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
// KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
// LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
// SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
// A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
// THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
// DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
//
package gov.nasa.jpf;

/**
 * helper class to avoid indirection if there is just one observer
 * (the usual case) Typical 'Container' pattern implementation
 */
public class SearchListenerMulticaster implements SearchListener {
    
  SearchListener head;
  SearchListener tail;

  public static SearchListener add (SearchListener oldListener, SearchListener newListener) {
    if (newListener == null) {
      return oldListener;
    }
    if (oldListener == null) {
      return newListener;
    }
    
    // we store in the order of registration, multiple entries are allowed
    // (but generally useless)
    return new SearchListenerMulticaster(oldListener, newListener);
  }

  public static SearchListener remove (SearchListener oldListener, SearchListener removeListener){
    if (oldListener == removeListener) {
      return null;
    }
    if (oldListener instanceof SearchListenerMulticaster){
      return ((SearchListenerMulticaster)oldListener).remove( removeListener);
    }
    
    return oldListener;
  }
  
  protected SearchListener remove (SearchListener listener) {
    if (listener == head) {
      return tail;
    }
    if (listener == tail){
      return head;
    }
    
    SearchListenerMulticaster h,t;
    if (head instanceof SearchListenerMulticaster) {
      h = (SearchListenerMulticaster)head;
      if (tail instanceof SearchListenerMulticaster){
        t = (SearchListenerMulticaster)tail;
        return new SearchListenerMulticaster( h.remove(listener),t.remove(listener));
      } else {
        return new SearchListenerMulticaster( h.remove(listener), tail);
      }
    } else if (tail instanceof SearchListenerMulticaster) {
      t = (SearchListenerMulticaster)tail;      
      return new SearchListenerMulticaster( head, t.remove(listener));
    }
    
    return this;
  }

  
  public SearchListenerMulticaster (SearchListener h, SearchListener t) {
    head = h;
    tail = t;
  }

  public void stateAdvanced (Search search) {
    head.stateAdvanced(search);
    tail.stateAdvanced(search);
  }

  public void stateProcessed (Search search) {
    head.stateProcessed(search);
    tail.stateProcessed(search);
  }
  
  public void stateBacktracked (Search search) {
    head.stateBacktracked(search);
    tail.stateBacktracked(search);
  }

  public void stateRestored (Search search) {
    head.stateRestored(search);
    tail.stateRestored(search);
  }
  
  public void propertyViolated (Search search) {
    head.propertyViolated(search);
    tail.propertyViolated(search);
  }

  public void searchStarted(Search search) {
    head.searchStarted(search);
    tail.searchStarted(search);
  }
  
  public void searchFinished(Search search) {
    head.searchFinished(search);
    tail.searchFinished(search);
  }
  
  public void searchConstraintHit(Search search) {
    head.searchConstraintHit(search);
    tail.searchConstraintHit(search);
  }

}