1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/**
6 * Licensed to the Apache Software Foundation (ASF) under one
7 * or more contributor license agreements. See the NOTICE file
8 * distributed with this work for additional information
9 * regarding copyright ownership. The ASF licenses this file
10 * to you under the Apache License, Version 2.0 (the
11 * "License"); you may not use this file except in compliance
12 * with the License. You may obtain a copy of the License at
13 *
14 * http://www.apache.org/licenses/LICENSE-2.0
15 *
16 * Unless required by applicable law or agreed to in writing,
17 * software distributed under the License is distributed on an
18 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
19 * KIND, either express or implied. See the License for the
20 * specific language governing permissions and limitations
21 * under the License.
22 */
23package com.sun.org.apache.xml.internal.security.c14n.helper;
24
25import com.sun.org.apache.xml.internal.security.utils.Constants;
26import org.w3c.dom.Attr;
27import java.io.Serializable;
28import java.util.Comparator;
29
30/**
31 * Compares two attributes based on the C14n specification.
32 *
33 * <UL>
34 * <LI>Namespace nodes have a lesser document order position than attribute
35 *   nodes.
36 * <LI> An element's namespace nodes are sorted lexicographically by
37 *   local name (the default namespace node, if one exists, has no
38 *   local name and is therefore lexicographically least).
39 * <LI> An element's attribute nodes are sorted lexicographically with
40 *   namespace URI as the primary key and local name as the secondary
41 *   key (an empty namespace URI is lexicographically least).
42 * </UL>
43 *
44 * @author Christian Geuer-Pollmann
45 */
46public class AttrCompare implements Comparator<Attr>, Serializable {
47
48    private static final long serialVersionUID = -7113259629930576230L;
49    private static final int ATTR0_BEFORE_ATTR1 = -1;
50    private static final int ATTR1_BEFORE_ATTR0 = 1;
51    private static final String XMLNS = Constants.NamespaceSpecNS;
52
53    /**
54     * Compares two attributes based on the C14n specification.
55     *
56     * <UL>
57     * <LI>Namespace nodes have a lesser document order position than
58     *   attribute nodes.
59     * <LI> An element's namespace nodes are sorted lexicographically by
60     *   local name (the default namespace node, if one exists, has no
61     *   local name and is therefore lexicographically least).
62     * <LI> An element's attribute nodes are sorted lexicographically with
63     *   namespace URI as the primary key and local name as the secondary
64     *   key (an empty namespace URI is lexicographically least).
65     * </UL>
66     *
67     * @param attr0
68     * @param attr1
69     * @return returns a negative integer, zero, or a positive integer as
70     *   obj0 is less than, equal to, or greater than obj1
71     *
72     */
73    public int compare(Attr attr0, Attr attr1) {
74        String namespaceURI0 = attr0.getNamespaceURI();
75        String namespaceURI1 = attr1.getNamespaceURI();
76
77        boolean isNamespaceAttr0 = XMLNS.equals(namespaceURI0);
78        boolean isNamespaceAttr1 = XMLNS.equals(namespaceURI1);
79
80        if (isNamespaceAttr0) {
81            if (isNamespaceAttr1) {
82                // both are namespaces
83                String localname0 = attr0.getLocalName();
84                String localname1 = attr1.getLocalName();
85
86                if ("xmlns".equals(localname0)) {
87                    localname0 = "";
88                }
89
90                if ("xmlns".equals(localname1)) {
91                    localname1 = "";
92                }
93
94                return localname0.compareTo(localname1);
95            }
96            // attr0 is a namespace, attr1 is not
97            return ATTR0_BEFORE_ATTR1;
98        } else if (isNamespaceAttr1) {
99            // attr1 is a namespace, attr0 is not
100            return ATTR1_BEFORE_ATTR0;
101        }
102
103        // none is a namespace
104        if (namespaceURI0 == null) {
105            if (namespaceURI1 == null) {
106                String name0 = attr0.getName();
107                String name1 = attr1.getName();
108                return name0.compareTo(name1);
109            }
110            return ATTR0_BEFORE_ATTR1;
111        } else if (namespaceURI1 == null) {
112            return ATTR1_BEFORE_ATTR0;
113        }
114
115        int a = namespaceURI0.compareTo(namespaceURI1);
116        if (a != 0) {
117            return a;
118        }
119
120        return (attr0.getLocalName()).compareTo(attr1.getLocalName());
121    }
122}
123