1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/StackedIterator.java,v 1.11 2005/06/28 13:44:44 elharo Exp $
3 * $Revision: 1.11 $
4 * $Date: 2005/06/28 13:44:44 $
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: StackedIterator.java,v 1.11 2005/06/28 13:44:44 elharo Exp $
60 */
61
62
63
64 package org.jaxen.util;
65
66 import java.util.HashSet;
67 import java.util.Iterator;
68 import java.util.LinkedList;
69 import java.util.NoSuchElementException;
70 import java.util.Set;
71
72 import org.jaxen.Navigator;
73
74 /***
75 * @deprecated this iterator is no longer used to implement any of the Jaxen axes. If you have implemented
76 * a navigator-specific axis based on this class, take a look at the DescendantAxisIterator for ideas
77 * on how to remove that dependency.
78 */
79 public abstract class StackedIterator implements Iterator
80 {
81
82 private LinkedList iteratorStack;
83 private Navigator navigator;
84
85 private Set created;
86
87 public StackedIterator(Object contextNode,
88 Navigator navigator)
89 {
90 this.iteratorStack = new LinkedList();
91 this.created = new HashSet();
92
93 init( contextNode,
94 navigator );
95 }
96
97 protected StackedIterator()
98 {
99 this.iteratorStack = new LinkedList();
100 this.created = new HashSet();
101 }
102
103 protected void init(Object contextNode,
104 Navigator navigator)
105 {
106 this.navigator = navigator;
107
108 //pushIterator( internalCreateIterator( contextNode ) );
109 }
110
111 protected Iterator internalCreateIterator(Object contextNode)
112 {
113 if ( this.created.contains( contextNode ) )
114 {
115 return null;
116 }
117
118 this.created.add( contextNode );
119
120 return createIterator( contextNode );
121 }
122
123 public boolean hasNext()
124 {
125 Iterator curIter = currentIterator();
126
127 if ( curIter == null )
128 {
129 return false;
130 }
131
132 return curIter.hasNext();
133 }
134
135 public Object next() throws NoSuchElementException
136 {
137 if ( ! hasNext() )
138 {
139 throw new NoSuchElementException();
140 }
141
142 Iterator curIter = currentIterator();
143 Object object = curIter.next();
144
145 pushIterator( internalCreateIterator( object ) );
146
147 return object;
148 }
149
150 public void remove() throws UnsupportedOperationException
151 {
152 throw new UnsupportedOperationException();
153 }
154
155 abstract protected Iterator createIterator(Object contextNode);
156
157 protected void pushIterator(Iterator iter)
158 {
159 if ( iter != null )
160 {
161 this.iteratorStack.addFirst(iter); //addLast( iter );
162 }
163 }
164
165 private Iterator currentIterator()
166 {
167 while ( iteratorStack.size() > 0 )
168 {
169 Iterator curIter = (Iterator) iteratorStack.getFirst();
170
171 if ( curIter.hasNext() )
172 {
173 return curIter;
174 }
175
176 iteratorStack.removeFirst();
177 }
178
179 return null;
180 }
181
182 protected Navigator getNavigator()
183 {
184 return this.navigator;
185 }
186 }