content: package org.jaxen.util;
  
  /*
   * $Header$
   * $Revision$
   * $Date$
   *
   * ====================================================================
   *
   * Copyright 2000-2005 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/>.
   *
   * $Id$
  */
  
  import org.jaxen.Navigator;
  import org.jaxen.UnsupportedAxisException;
  import org.jaxen.JaxenRuntimeException;
  
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  import java.util.ArrayList;
  
  /**
   * Represents the XPath <code>descendant</code> axis. 
   * The "<code>descendant</code> axis contains the descendants of the context node; 
   * a descendant is a child or a child of a child and so on; thus 
   * the descendant axis never contains attribute or namespace nodes."
   * 
   * @version 1.2b12
   */
  public class DescendantAxisIterator implements Iterator
  {
  
      private ArrayList stack = new ArrayList();
      private Iterator children;
      private Navigator navigator;
  
      /**
       * Create a new <code>descendant</code> axis iterator.
       * 
       * @param contextNode the node to start from
       * @param navigator the object model specific navigator
       */
      public DescendantAxisIterator(Object contextNode,
                                    Navigator navigator) throws UnsupportedAxisException
      {
          this(navigator, navigator.getChildAxisIterator(contextNode));
      }
  
      public DescendantAxisIterator(Navigator navigator,
                                    Iterator iterator)
      {
          this.navigator = navigator;
          this.children = iterator;
      }
  
      /**
       * Returns true if there are any descendants remaining; false otherwise.
       * 
       * @return true if any descendants remain; false otherwise
       * 
       * @see java.util.Iterator#hasNext()
       */    public boolean hasNext()
      {
          while (!children.hasNext())
          {
              if (stack.isEmpty())
              {
                  return false;
              }
              children = (Iterator) stack.remove(stack.size()-1);
          }
          return true;
      }
  
      /**
       * Returns the next descendant node.
       * 
       * @return the next descendant node
       * 
       * @throws NoSuchElementException if no descendants remain
       * 
       * @see java.util.Iterator#next()
       */
      public Object next()
      {
          try
          {
              if (hasNext())
              {
                  Object node = children.next();
                  stack.add(children);
                  children = navigator.getChildAxisIterator(node);
                  return node;
              }
              throw new NoSuchElementException();
          }
          catch (UnsupportedAxisException e)
          {
              throw new JaxenRuntimeException(e);
          }
      }
  
      /**
       * This operation is not supported.
       * 
       * @throws UnsupportedOperationException always
       */
      public void remove()
      {
          throw new UnsupportedOperationException();
      }
  
  }
  