/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.aspects.patterns.observable;

import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**
 * The subject implementation.
 * 
 * @author <a href="adrian@jboss.com">Adrian Brock</a>
 * @version $Revision: 1.1.4.4 $
 */
public class SubjectImpl implements Subject
{
   /** The observers */
   private Set observers = Collections.synchronizedSet(new HashSet());
   
   /** The subject */
   private Object subject;

   public SubjectImpl(Object subject)
   {
      this.subject = subject;
   }
   
   public void addObserver(Observer observer)
   {
      if(observers.contains(observer))
         return;  // return right away since we have that already.
      observers.add(observer);
   }
   
   public void removeObserver(Observer observer)
   {
      observers.remove(observer);
   }
   
   public void notifyObservers()
   {
      Subject obj = (Subject) subject;
      
      synchronized (observers)
      {
         for (Iterator i = observers.iterator(); i.hasNext();)
         {
            Observer observer = (Observer) i.next();
            observer.fireChange(obj);
         }
      }
   }
}
