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1   /*
2    * Copyright 2001-2004 (C) MetaStuff, Ltd. All Rights Reserved.
3    * 
4    * This software is open source. 
5    * See the bottom of this file for the licence.
6    * 
7    * $Id: FilterIterator.java,v 1.8 2004/06/25 08:03:41 maartenc Exp $
8    */
9   
10  package org.dom4j.tree;
11  
12  import java.util.Iterator;
13  import java.util.NoSuchElementException;
14  
15  /*** <p><code>FilterIterator</code> is an abstract base class which is useful
16    * for implementors of {@link Iterator} which filter an existing iterator.
17    *
18    * @author <a href="mailto:james.strachan@metastuff.com">James Strachan</a>
19    * @version $Revision: 1.8 $
20    * @deprecated  THIS CLASS WILL BE REMOVED IN dom4j-1.6 !!
21    */
22  public abstract class FilterIterator implements Iterator {
23      
24      protected Iterator proxy;
25      private Object next;
26      private boolean first = true;
27      
28      public FilterIterator(Iterator proxy) {
29          this.proxy = proxy;
30      }
31  
32  
33      public boolean hasNext() {
34          if ( first ) {
35              next = findNext();
36              first = false;
37          }
38          return next != null;
39      }
40  
41      public Object next() throws NoSuchElementException {
42          if ( ! hasNext() ) {
43              throw new NoSuchElementException();
44          }
45          Object answer = this.next;
46          this.next = findNext();
47          return answer;
48      }
49  
50      /***
51       * Always throws UnsupportedOperationException as this class 
52       * does look-ahead with its internal iterator.
53       *
54       * @throws UnsupportedOperationException  always
55       */
56      public void remove() {
57          throw new UnsupportedOperationException();
58      }
59      
60      /*** Filter method to perform some matching on the given element.
61        * 
62        * @return true if the given element matches the filter
63        * and should be appear in the iteration
64        */
65      protected abstract boolean matches(Object element);
66      
67      
68      protected Object findNext() {
69          if ( proxy != null ) {
70              while (proxy.hasNext()) {
71                  Object next = proxy.next();
72                  if ( next != null &&  matches(next) ) {
73                      return next;
74                  }
75              }
76              proxy = null;
77          }
78          return null;
79      }
80  }
81  
82  
83  
84  
85  /*
86   * Redistribution and use of this software and associated documentation
87   * ("Software"), with or without modification, are permitted provided
88   * that the following conditions are met:
89   *
90   * 1. Redistributions of source code must retain copyright
91   *    statements and notices.  Redistributions must also contain a
92   *    copy of this document.
93   *
94   * 2. Redistributions in binary form must reproduce the
95   *    above copyright notice, this list of conditions and the
96   *    following disclaimer in the documentation and/or other
97   *    materials provided with the distribution.
98   *
99   * 3. The name "DOM4J" must not be used to endorse or promote
100  *    products derived from this Software without prior written
101  *    permission of MetaStuff, Ltd.  For written permission,
102  *    please contact dom4j-info@metastuff.com.
103  *
104  * 4. Products derived from this Software may not be called "DOM4J"
105  *    nor may "DOM4J" appear in their names without prior written
106  *    permission of MetaStuff, Ltd. DOM4J is a registered
107  *    trademark of MetaStuff, Ltd.
108  *
109  * 5. Due credit should be given to the DOM4J Project - 
110  *    http://www.dom4j.org
111  *
112  * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS
113  * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
114  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
115  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
116  * METASTUFF, LTD. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
117  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
118  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
119  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
120  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
121  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
122  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
123  * OF THE POSSIBILITY OF SUCH DAMAGE.
124  *
125  * Copyright 2001-2004 (C) MetaStuff, Ltd. All Rights Reserved.
126  *
127  * $Id: FilterIterator.java,v 1.8 2004/06/25 08:03:41 maartenc Exp $
128  */