FilterIterator


1   /*--
2   
3    $Id: FilterIterator.java,v 1.5 2004/08/31 19:36:12 jhunter Exp $
4   
5    Copyright (C) 2000-2004 Jason Hunter & Brett McLaughlin.
6    All rights reserved.
7   
8    Redistribution and use in source and binary forms, with or without
9    modification, are permitted provided that the following conditions
10   are met:
11  
12   1. Redistributions of source code must retain the above copyright
13      notice, this list of conditions, and the following disclaimer.
14  
15   2. Redistributions in binary form must reproduce the above copyright
16      notice, this list of conditions, and the disclaimer that follows
17      these conditions in the documentation and/or other materials
18      provided with the distribution.
19  
20   3. The name "JDOM" must not be used to endorse or promote products
21      derived from this software without prior written permission.  For
22      written permission, please contact <request_AT_jdom_DOT_org>.
23  
24   4. Products derived from this software may not be called "JDOM", nor
25      may "JDOM" appear in their name, without prior written permission
26      from the JDOM Project Management <request_AT_jdom_DOT_org>.
27  
28   In addition, we request (but do not require) that you include in the
29   end-user documentation provided with the redistribution and/or in the
30   software itself an acknowledgement equivalent to the following:
31       "This product includes software developed by the
32        JDOM Project (http://www.jdom.org/)."
33   Alternatively, the acknowledgment may be graphical using the logos
34   available at http://www.jdom.org/images/logos.
35  
36   THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
37   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
38   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
39   DISCLAIMED.  IN NO EVENT SHALL THE JDOM AUTHORS OR THE PROJECT
40   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
42   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
43   USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
44   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
45   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
46   OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
47   SUCH DAMAGE.
48  
49   This software consists of voluntary contributions made by many
50   individuals on behalf of the JDOM Project and was originally
51   created by Jason Hunter <jhunter_AT_jdom_DOT_org> and
52   Brett McLaughlin <brett_AT_jdom_DOT_org>.  For more information
53   on the JDOM Project, please see <http://www.jdom.org/>.
54  
55   */
56  
57  package org.jdom;
58  
59  import java.util.*;
60  import org.jdom.filter.*;
61  
62  /**
63   * Traverse a parent's children that match the supplied filter.
64   *
65   * @author Bradley S. Huffman
66   * @version $Revision: 1.5 $, $Date: 2004/08/31 19:36:12 $
67   */
68  class FilterIterator implements Iterator {
69  
70      private Iterator iterator;
71      private Filter filter;
72      private Object   nextObject;
73  
74      private static final String   CVS_ID =
75              "@(#) $RCSfile: FilterIterator.java,v $ $Revision: 1.5 $ $Date: 2004/08/31 19:36:12 $ $Name:  $";
76  
77      public FilterIterator(Iterator iterator, Filter filter) {
78          if ((iterator == null) || (filter == null)) {
79              throw new IllegalArgumentException  ("null parameter");
80          }
81          this.iterator = iterator;
82          this.filter = filter;
83      }
84  
85      public boolean hasNext() {
86          if (nextObject != null) {
87              return true;
88          }
89  
90          while (iterator.hasNext()) {
91              Object   obj = iterator.next();
92              if (filter.matches(obj)) {
93                  nextObject = obj;
94                  return true;
95              }
96          }
97          return false;
98      }
99  
100     public Object   next() {
101         if (!hasNext()) {
102             throw new NoSuchElementException();
103         }
104 
105         Object   obj = nextObject;
106         nextObject = null;
107         return obj;
108     }
109 
110     public void remove() {
111         // XXX Could cause probs for sure if hasNext() is
112         // called before the remove(), although that's unlikely.
113         iterator.remove();
114     }
115 }
116
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