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1   /*
2    * $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 $
3    * $Revision: 1.16 $
4    * $Date: 2006/11/13 22:10:09 $
5    *
6    * ====================================================================
7    *
8    * Copyright 2000-2002 bob mcwhirter & James Strachan.
9    * All rights reserved.
10   *
11   * Redistribution and use in source and binary forms, with or without
12   * modification, are permitted provided that the following conditions are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: PrecedingSiblingAxisIterator.java,v 1.16 2006/11/13 22:10:09 elharo Exp $
46   */
47  
48  
49  
50  package org.jaxen.util;
51  
52  import java.util.Iterator;
53  import java.util.LinkedList;
54  import java.util.NoSuchElementException;
55  
56  import org.jaxen.JaxenConstants;
57  import org.jaxen.Navigator;
58  import org.jaxen.UnsupportedAxisException;
59  
60  /***
61   * 
62   * Represents the XPath <code>preceding-sibling</code> axis. 
63   * The "<code>preceding-sibling</code> axis contains all the
64   * preceding siblings of the context node; if the context node is an
65   * attribute node or namespace node, the <code>preceding-sibling</code>
66   * axis is empty."
67   * 
68   * @version 1.2b12
69   *
70   */
71  public class PrecedingSiblingAxisIterator implements Iterator
72  {
73      private Object    contextNode;
74      private Navigator navigator;
75  
76      private Iterator  siblingIter;
77      private Object    nextObj;
78  
79      /***
80       * Create a new <code>preceding-sibling</code> axis iterator.
81       * 
82       * @param contextNode the node to start from
83       * @param navigator the object model specific navigator
84       */
85      public PrecedingSiblingAxisIterator(Object contextNode,
86                                          Navigator navigator) throws UnsupportedAxisException
87      {
88          this.contextNode = contextNode;
89          this.navigator   = navigator;
90  
91          init();
92          if ( siblingIter.hasNext() )
93          {
94              this.nextObj = siblingIter.next();
95          }
96      }
97  
98      private void init() throws UnsupportedAxisException
99      {
100         
101         Object parent = this.navigator.getParentNode( this.contextNode );
102 
103         if ( parent != null )
104         {
105             Iterator childIter = this.navigator.getChildAxisIterator( parent );
106             LinkedList siblings = new LinkedList();
107             
108             while ( childIter.hasNext() )
109             {
110                 Object eachChild = childIter.next();
111                 if ( eachChild.equals(this.contextNode) )
112                 {
113                     break;
114                 }
115                 siblings.addFirst( eachChild );
116             }
117             
118             this.siblingIter = siblings.iterator();
119             
120         }
121         else {
122             this.siblingIter = JaxenConstants.EMPTY_ITERATOR;
123         }
124         
125     }
126 
127     /***
128      * Returns true if there are any preceding siblings remaining; false otherwise.
129      * 
130      * @return true if any preceding siblings remain; false otherwise
131      * 
132      * @see java.util.Iterator#hasNext()
133      */
134     public boolean hasNext()
135     {
136         return ( this.nextObj != null );
137     }
138 
139     /***
140      * Returns the next preceding sibling.
141      * 
142      * @return the next preceding sibling
143      * 
144      * @throws NoSuchElementException if no preceding siblings remain
145      * 
146      * @see java.util.Iterator#next()
147      */
148     public Object next() throws NoSuchElementException
149     {
150         if ( ! hasNext() )
151         {
152             throw new NoSuchElementException();
153         }
154 
155         Object obj = this.nextObj;
156         if ( siblingIter.hasNext() )
157         {
158             this.nextObj = siblingIter.next();
159         }
160         else {
161             this.nextObj = null;
162         }
163         return obj;
164     }
165 
166     /***
167      * This operation is not supported.
168      * 
169      * @throws UnsupportedOperationException
170      */
171     public void remove() throws UnsupportedOperationException
172     {
173         throw new UnsupportedOperationException();
174     }
175 
176 }