content: /*
   * $Header$
   * $Revision$
   * $Date$
   *
   * ====================================================================
   *
   * Copyright 2000-2002 bob mcwhirter & James Strachan.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   * 
   *   * Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   * 
   *   * Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   * 
   *   * Neither the name of the Jaxen Project nor the names of its
   *     contributors may be used to endorse or promote products derived 
   *     from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * ====================================================================
   * This software consists of voluntary contributions made by many 
   * individuals on behalf of the Jaxen Project and was originally 
   * created by bob mcwhirter <bob@werken.com> and 
   * James Strachan <jstrachan@apache.org>.  For more information on the 
   * Jaxen Project, please see <http://www.jaxen.org/>.
   * 
   * $Id$
   */
  
  
  
  package org.jaxen.util;
  
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.NoSuchElementException;
  import java.util.Set;
  
  import org.jaxen.Navigator;
  
  /**
   * @deprecated this iterator is no longer used to implement any of the Jaxen axes. If you have implemented
   * a navigator-specific axis based on this class, take a look at the DescendantAxisIterator for ideas 
   * on how to remove that dependency.
   */
  public abstract class StackedIterator implements Iterator
  {
  
      private LinkedList iteratorStack;
      private Navigator  navigator;
  
      private Set        created;
  
      public StackedIterator(Object contextNode,
                             Navigator navigator)
      {
          this.iteratorStack = new LinkedList();
          this.created       = new HashSet();
  
          init( contextNode,
                navigator );
      }
  
      protected StackedIterator()
      {
          this.iteratorStack = new LinkedList();
          this.created       = new HashSet();
      }
  
      protected void init(Object contextNode,
                          Navigator navigator)
      {
          this.navigator     = navigator;
          
          //pushIterator( internalCreateIterator( contextNode ) );
      }
  
      protected Iterator internalCreateIterator(Object contextNode)
      {
          if ( this.created.contains( contextNode ) )
          {
              return null;
          }
  
          this.created.add( contextNode );
  
          return createIterator( contextNode );
      }
  
      public boolean hasNext()
      {
          Iterator curIter = currentIterator();
  
          if ( curIter == null )
          {
              return false;
          }
  
          return curIter.hasNext();
      }
  
      public Object next() throws NoSuchElementException
      {
          if ( ! hasNext() )
          {
              throw new NoSuchElementException();
          }
  
          Iterator curIter = currentIterator();
          Object   object  = curIter.next();
  
          pushIterator( internalCreateIterator( object ) );
  
          return object;
      }
  
      public void remove() throws UnsupportedOperationException
      {
          throw new UnsupportedOperationException();
      }
  
      abstract protected Iterator createIterator(Object contextNode);
  
      protected void pushIterator(Iterator iter)
      {
          if ( iter != null )
          {
              this.iteratorStack.addFirst(iter); //addLast( iter );
          }
      }
  
      private Iterator currentIterator()
      {
          while ( iteratorStack.size() > 0 )
          {
              Iterator curIter = (Iterator) iteratorStack.getFirst();
  
              if ( curIter.hasNext() )
              {
                  return curIter;
              }
  
              iteratorStack.removeFirst();
          }
  
          return null;
      }
  
      protected Navigator getNavigator()
      {
          return this.navigator;
      }
  }
  