1/*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements.  See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License.  You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package com.sun.org.apache.xml.internal.resolver.helpers;
19
20import org.w3c.dom.*;
21
22/**
23 * Static Namespace query methods.
24 *
25 * <p>This class defines a set of static methods that can be called
26 * to analyze the namespace properties of DOM nodes.</p>
27 *
28 * @author Norman Walsh
29 * <a href="mailto:Norman.Walsh@Sun.COM">Norman.Walsh@Sun.COM</a>
30 *
31 */
32public class Namespaces {
33    /**
34     * Returns the "prefix" part of a QName or the empty string (not
35     * null) if the name has no prefix.
36     *
37     * @param element The QName of an element.
38     * @return The prefix part of the element name.
39     */
40    public static String getPrefix(Element element) {
41        String name = element.getTagName();
42        String prefix = "";
43
44        final int indexOfColon = name.indexOf(':');
45        if (indexOfColon > 0) {
46            prefix = name.substring(0, indexOfColon);
47        }
48
49        return prefix;
50    }
51
52    /**
53     * Returns the "localname" part of a QName, which is the whole
54     * name if it has no prefix.
55     *
56     * @param element The QName of an element.
57     * @return The local part of a QName.
58     */
59    public static String getLocalName(Element element) {
60        String name = element.getTagName();
61
62        final int indexOfColon = name.indexOf(':');
63        if (indexOfColon > 0) {
64            name = name.substring(indexOfColon + 1);
65        }
66
67        return name;
68    }
69
70    /**
71     * Returns the namespace URI for the specified prefix at the
72     * specified context node.
73     *
74     * @param node The context node.
75     * @param prefix The prefix.
76     * @return The namespace URI associated with the prefix, or
77     * null if no namespace declaration exists for the prefix.
78     */
79    public static String getNamespaceURI(Node node, String prefix) {
80        if (node == null || node.getNodeType() != Node.ELEMENT_NODE) {
81            return null;
82        }
83
84        if (prefix.length() == 0) {
85            if (((Element) node).hasAttribute("xmlns")) {
86                return ((Element) node).getAttribute("xmlns");
87            }
88        } else {
89            String nsattr = "xmlns:" + prefix;
90            if (((Element) node).hasAttribute(nsattr)) {
91                return ((Element) node).getAttribute(nsattr);
92            }
93        }
94
95        return getNamespaceURI(node.getParentNode(), prefix);
96    }
97
98    /**
99     * Returns the namespace URI for the namespace to which the
100     * element belongs.
101     *
102     * @param element The element.
103     * @return The namespace URI associated with the namespace of the
104     * element, or null if no namespace declaration exists for it.
105     */
106    public static String getNamespaceURI(Element element) {
107        String prefix = getPrefix(element);
108        return getNamespaceURI(element, prefix);
109    }
110}
111