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 */