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 }