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 try { 85 return compare(navigator.getParentNode(o1), navigator.getParentNode(o2)); 86 } 87 catch (UnsupportedAxisException ex) { 88 return 0; 89 } 90 } 91 92 try { 93 int depth1 = getDepth(o1); 94 int depth2 = getDepth(o2); 95 96 Object a1 = o1; 97 Object a2 = o2; 98 99 while (depth1 > depth2) { 100 a1 = navigator.getParentNode(a1); 101 depth1--; 102 } 103 if (a1 == o2) return 1; 104 105 while (depth2 > depth1) { 106 a2 = navigator.getParentNode(a2); 107 depth2--; 108 } 109 if (a2 == o1) return -1; 110 111 // a1 and a2 are now at same depth; and are not the same 112 while (true) { 113 Object p1 = navigator.getParentNode(a1); 114 Object p2 = navigator.getParentNode(a2); 115 if (p1 == p2) { 116 return compareSiblings(a1, a2); 117 } 118 a1 = p1; 119 a2 = p2; 120 } 121 122 } 123 catch (UnsupportedAxisException ex) { 124 return 0; // ???? should I throw an exception instead? 125 } 126 } 127 128 129 private boolean isNonChild(Object o) { 130 return navigator.isAttribute(o) || navigator.isNamespace(o); 131 } 132 133 private int compareSiblings(Object sib1, Object sib2) 134 throws UnsupportedAxisException { 135 136 Iterator following = navigator.getFollowingSiblingAxisIterator(sib1); 137 while (following.hasNext()) { 138 Object next = following.next(); 139 if (next.equals(sib2)) return -1; 140 } 141 return 1; 142 143 } 144 145 private int getDepth(Object o) throws UnsupportedAxisException { 146 147 int depth = 0; 148 Object parent = o; 149 150 while ((parent = navigator.getParentNode(parent)) != null) { 151 depth++; 152 } 153 return depth; 154 155 } 156 157 }