1 /*
2 * $Header$
3 * $Revision$
4 * $Date$
5 *
6 * ====================================================================
7 *
8 * Copyright (C) 2005 Elliotte Rusty Harold.
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 * $Id$
60 */
61 package org.jaxen.expr;
62
63 import java.util.Comparator;
64 import java.util.Iterator;
65
66 import org.jaxen.Navigator;
67 import org.jaxen.UnsupportedAxisException;
68
69
70 class NodeComparator implements Comparator {
71
72 private Navigator navigator;
73
74
75 NodeComparator(Navigator navigator) {
76 this.navigator = navigator;
77 }
78
79 public int compare(Object o1, Object o2) {
80
81 if (navigator == null) return 0;
82
83 if (isNonChild(o1) && isNonChild(o2)) {
84
85 try {
86 Object p1 = navigator.getParentNode(o1);
87 Object p2 = navigator.getParentNode(o2);
88
89 if (p1 == p2) {
90 if (navigator.isNamespace(o1) && navigator.isAttribute(o2)) {
91 return -1;
92 }
93 else if (navigator.isNamespace(o2) && navigator.isAttribute(o1)) {
94 return 1;
95 }
96 }
97
98 return compare(p1, p2);
99 }
100 catch (UnsupportedAxisException ex) {
101 return 0;
102 }
103
104 }
105
106 try {
107 int depth1 = getDepth(o1);
108 int depth2 = getDepth(o2);
109
110 Object a1 = o1;
111 Object a2 = o2;
112
113 while (depth1 > depth2) {
114 a1 = navigator.getParentNode(a1);
115 depth1--;
116 }
117 if (a1 == o2) return 1;
118
119 while (depth2 > depth1) {
120 a2 = navigator.getParentNode(a2);
121 depth2--;
122 }
123 if (a2 == o1) return -1;
124
125 // a1 and a2 are now at same depth; and are not the same
126 while (true) {
127 Object p1 = navigator.getParentNode(a1);
128 Object p2 = navigator.getParentNode(a2);
129 if (p1 == p2) {
130 return compareSiblings(a1, a2);
131 }
132 a1 = p1;
133 a2 = p2;
134 }
135
136 }
137 catch (UnsupportedAxisException ex) {
138 return 0; // ???? should I throw an exception instead?
139 }
140 }
141
142
143 private boolean isNonChild(Object o) {
144 return navigator.isAttribute(o) || navigator.isNamespace(o);
145 }
146
147 private int compareSiblings(Object sib1, Object sib2)
148 throws UnsupportedAxisException {
149
150 Iterator following = navigator.getFollowingSiblingAxisIterator(sib1);
151 while (following.hasNext()) {
152 Object next = following.next();
153 if (next.equals(sib2)) return -1;
154 }
155 return 1;
156
157 }
158
159 private int getDepth(Object o) throws UnsupportedAxisException {
160
161 int depth = 0;
162 Object parent = o;
163
164 while ((parent = navigator.getParentNode(parent)) != null) {
165 depth++;
166 }
167 return depth;
168
169 }
170
171 }