package org.jaxen.util;

 /*

  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/DescendantAxisIterator.java,v 1.13 2006/11/09 18:20:11 elharo Exp $

  * $Revision: 1.13 $

  * $Date: 2006/11/09 18:20:11 $

  *

  * ====================================================================

  *

  * 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: DescendantAxisIterator.java,v 1.13 2006/11/09 18:20:11 elharo Exp $

 */

 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();

     }

 }