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Java > Open Source Codes > org > jdom > DescendantIterator


1 /*--
2
3  $Id: DescendantIterator.java,v 1.5 2004/02/27 11:32:57 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.Content;
61 import org.jdom.Element;
62 import org.jdom.Parent;
63
64 /**
65  * Traverse all a parent's descendants (all children at any level below
66  * the parent).
67  *
68  * @author Bradley S. Huffman
69  * @author Jason Hunter
70  * @version $Revision: 1.5 $, $Date: 2004/02/27 11:32:57 $
71  */
72 class DescendantIterator implements Iterator {
73
74     private Iterator iterator;
75     private Iterator nextIterator;
76     private List stack = new ArrayList();
77
78     private static final String JavaDoc CVS_ID =
79             "@(#) $RCSfile: DescendantIterator.java,v $ $Revision: 1.5 $ $Date: 2004/02/27 11:32:57 $ $Name: $";
80
81     /**
82      * Iterator for the descendants of the supplied object.
83      *
84      * @param parent document or element whose descendants will be iterated
85      */
86     DescendantIterator(Parent parent) {
87         if (parent == null) {
88             throw new IllegalArgumentException JavaDoc("parent parameter was null");
89         }
90         this.iterator = parent.getContent().iterator();
91     }
92
93     /**
94      * Returns true> if the iteration has more {@link Content} descendants.
95      *
96      * @return true is the iterator has more descendants
97      */
98     public boolean hasNext() {
99         if (iterator != null && iterator.hasNext()) return true;
100         if (nextIterator != null && nextIterator.hasNext()) return true;
101         if (stackHasAnyNext()) return true;
102         return false;
103     }
104
105     /**
106      * Returns the next {@link Content} descendant.
107      *
108      * @return the next descendant
109      */
110     public Object JavaDoc next() {
111         if (!hasNext()) {
112             throw new NoSuchElementException();
113         }
114
115         // If we need to descend, go for it and record where we are.
116 // We do the shuffle here on the next next() call so remove() is easy
117 // to code up.
118 if (nextIterator != null) {
119             push(iterator);
120             iterator = nextIterator;
121             nextIterator = null;
122         }
123
124         // If this iterator is finished, try moving up the stack
125 while (!iterator.hasNext()) {
126             if (stack.size() > 0) {
127                 iterator = pop();
128             }
129             else {
130               throw new NoSuchElementException("Somehow we lost our iterator");
131             }
132         }
133
134         Content child = (Content) iterator.next();
135         if (child instanceof Element) {
136             nextIterator = ((Element)child).getContent().iterator();
137         }
138         return child;
139     }
140
141     /**
142      * Detaches the last {@link org.jdom.Content} returned by the last call to
143      * next from it's parent. <b>Note</b>: this <b>does not</b> affect
144      * iteration and all children, siblings, and any node following the
145      * removed node (in document order) will be visited.
146      */
147     public void remove() {
148         iterator.remove();
149     }
150
151     private Iterator pop() {
152         int stackSize = stack.size();
153         if (stackSize == 0) {
154             throw new NoSuchElementException("empty stack");
155         }
156         return (Iterator) stack.remove(stackSize - 1);
157     }
158
159     private void push(Iterator itr) {
160         stack.add(itr);
161     }
162
163     private boolean stackHasAnyNext() {
164         int size = stack.size();
165         for (int i = 0; i < size; i++) {
166             Iterator itr = (Iterator) stack.get(i);
167             if (itr.hasNext()) {
168                 return true;
169             }
170         }
171         return false;
172     }
173 }
174
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