/*

  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/PrecedingSiblingAxisIterator.java,v 1.16 2006/11/13 22:10:09 elharo Exp $

  * $Revision: 1.16 $

  * $Date: 2006/11/13 22:10:09 $

  *

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

  *

  * 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: PrecedingSiblingAxisIterator.java,v 1.16 2006/11/13 22:10:09 elharo Exp $

  */

 package org.jaxen.util;

 import java.util.Iterator;

 import java.util.LinkedList;

 import java.util.NoSuchElementException;

 import org.jaxen.JaxenConstants;

 import org.jaxen.Navigator;

 import org.jaxen.UnsupportedAxisException;

 /**

  * 

  * Represents the XPath <code>preceding-sibling</code> axis. 

  * The "<code>preceding-sibling</code> axis contains all the

  * preceding siblings of the context node; if the context node is an

  * attribute node or namespace node, the <code>preceding-sibling</code>

  * axis is empty."

  * 

  * @version 1.2b12

  *

  */

 public class PrecedingSiblingAxisIterator implements Iterator

 {

     private Object    contextNode;

     private Navigator navigator;

     private Iterator  siblingIter;

     private Object    nextObj;

     /**

      * Create a new <code>preceding-sibling</code> axis iterator.

      * 

      * @param contextNode the node to start from

      * @param navigator the object model specific navigator

      */

     public PrecedingSiblingAxisIterator(Object contextNode,

                                         Navigator navigator) throws UnsupportedAxisException

     {

         this.contextNode = contextNode;

         this.navigator   = navigator;

         init();

         if ( siblingIter.hasNext() )

         {

             this.nextObj = siblingIter.next();

         }

     }

     private void init() throws UnsupportedAxisException

     {

         Object parent = this.navigator.getParentNode( this.contextNode );

         if ( parent != null )

         {

             Iterator childIter = this.navigator.getChildAxisIterator( parent );

             LinkedList siblings = new LinkedList();

             while ( childIter.hasNext() )

             {

                 Object eachChild = childIter.next();

                 if ( eachChild.equals(this.contextNode) )

                 {

                     break;

                 }

                 siblings.addFirst( eachChild );

             }

             this.siblingIter = siblings.iterator();

         }

         else {

             this.siblingIter = JaxenConstants.EMPTY_ITERATOR;

         }

     }

     /**

      * Returns true if there are any preceding siblings remaining; false otherwise.

      * 

      * @return true if any preceding siblings remain; false otherwise

      * 

      * @see java.util.Iterator#hasNext()

      */

     public boolean hasNext()

     {

         return ( this.nextObj != null );

     }

     /**

      * Returns the next preceding sibling.

      * 

      * @return the next preceding sibling

      * 

      * @throws NoSuchElementException if no preceding siblings remain

      * 

      * @see java.util.Iterator#next()

      */

     public Object next() throws NoSuchElementException

     {

         if ( ! hasNext() )

         {

             throw new NoSuchElementException();

         }

         Object obj = this.nextObj;

         if ( siblingIter.hasNext() )

         {

             this.nextObj = siblingIter.next();

         }

         else {

             this.nextObj = null;

         }

         return obj;

     }

     /**

      * This operation is not supported.

      * 

      * @throws UnsupportedOperationException

      */

     public void remove() throws UnsupportedOperationException

     {

         throw new UnsupportedOperationException();

     }

 }