/*
  * 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 test.dbc.stack;

import java.util.LinkedList;

/**
 * 
 * @author <a href="mailto:kabir.khan@jboss.org">Kabir Khan </a>
 * @version $Revision: 71280 $
 */
@SuppressWarnings("unchecked")
public class StackImpl implements Stack
{
   private final LinkedList elements = new LinkedList();

   public void push(Object o)
   {
      elements.add(o);
   }

   public Object pop()
   {
      //For this we need $old functionality
      //* @@org.jboss.aspects.dbc.PostCond ({"$tgt.top() == $rtn"})
      final Object popped = top();
      elements.removeLast();
      return popped;
   }

   public Object top()
   {
      if (elements.size() == 0)
      {
         return null;
      }
      return elements.getLast();
   }

   public boolean isEmpty()
   {
      return elements.size() == 0;
   }
}

