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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/LinkedIterator.java,v 1.4 2003/06/29 18:01:34 ssanders Exp $
3    * $Revision: 1.4 $
4    * $Date: 2003/06/29 18:01:34 $
5    *
6    * ====================================================================
7    *
8    * Copyright (C) 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
13   * are met:
14   * 
15   * 1. Redistributions of source code must retain the above copyright
16   *    notice, this list of conditions, and the following disclaimer.
17   *
18   * 2. Redistributions in binary form must reproduce the above copyright
19   *    notice, this list of conditions, and the disclaimer that follows 
20   *    these conditions in the documentation and/or other materials 
21   *    provided with the distribution.
22   *
23   * 3. The name "Jaxen" must not be used to endorse or promote products
24   *    derived from this software without prior written permission.  For
25   *    written permission, please contact license@jaxen.org.
26   * 
27   * 4. Products derived from this software may not be called "Jaxen", nor
28   *    may "Jaxen" appear in their name, without prior written permission
29   *    from the Jaxen Project Management (pm@jaxen.org).
30   * 
31   * In addition, we request (but do not require) that you include in the 
32   * end-user documentation provided with the redistribution and/or in the 
33   * software itself an acknowledgement equivalent to the following:
34   *     "This product includes software developed by the
35   *      Jaxen Project (http://www.jaxen.org/)."
36   * Alternatively, the acknowledgment may be graphical using the logos 
37   * available at http://www.jaxen.org/
38   *
39   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
40   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
41   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
42   * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
43   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
45   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
46   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
47   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
48   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
49   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50   * SUCH DAMAGE.
51   *
52   * ====================================================================
53   * This software consists of voluntary contributions made by many 
54   * individuals on behalf of the Jaxen Project and was originally 
55   * created by bob mcwhirter <bob@werken.com> and 
56   * James Strachan <jstrachan@apache.org>.  For more information on the 
57   * Jaxen Project, please see <http://www.jaxen.org/>.
58   * 
59   * $Id: LinkedIterator.java,v 1.4 2003/06/29 18:01:34 ssanders Exp $
60   */
61  
62  
63  package org.jaxen.util;
64  
65  import java.util.ArrayList;
66  import java.util.Iterator;
67  import java.util.List;
68  import java.util.NoSuchElementException;
69  
70  public class LinkedIterator implements Iterator
71  {
72      private List iterators;
73      private int  cur;
74  
75      public LinkedIterator()
76      {
77          this.iterators = new ArrayList();
78          this.cur       = 0;
79      }
80  
81      public void addIterator(Iterator i)
82      {
83          this.iterators.add( i );
84      }
85  
86      public boolean hasNext()
87      {
88          boolean has = false;
89  
90          if ( this.cur < this.iterators.size() )
91          {
92              has = ((Iterator)this.iterators.get( this.cur )).hasNext();
93  
94              if ( ! has
95                   &&
96                   this.cur < this.iterators.size() )
97              {
98                  ++this.cur;
99                  has = hasNext();
100             }
101         }
102         else
103         {
104             has = false;
105         }
106 
107         return has;
108     }
109 
110     public Object next()
111     {
112         if ( ! hasNext() )
113         {
114             throw new NoSuchElementException();
115         }
116 
117         return ((Iterator)this.iterators.get( this.cur )).next();
118     }
119 
120     public void remove()
121     {
122         throw new UnsupportedOperationException();
123     }
124 }