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Java > Open Source Codes > org > jaxen > function > NamespaceUriFunction


1 /*
2  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NamespaceUriFunction.java,v 1.11 2005/06/26 16:07:23 elharo Exp $
3  * $Revision: 1.11 $
4  * $Date: 2005/06/26 16:07:23 $
5  *
6  * ====================================================================
7  *
8  * Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
9  * All rights reserved.
10  *
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12  * modification, are permitted provided that the following conditions
13  * are met:
14  *
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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
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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
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34  * "This product includes software developed by the
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36  * Alternatively, the acknowledgment may be graphical using the logos
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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
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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: NamespaceUriFunction.java,v 1.11 2005/06/26 16:07:23 elharo Exp $
60  */
61
62
63 package org.jaxen.function;
64
65 import java.util.List JavaDoc;
66
67 import org.jaxen.Context;
68 import org.jaxen.Function;
69 import org.jaxen.FunctionCallException;
70 import org.jaxen.Navigator;
71
72 /**
73  * <p>
74  * <b>4.1</b>
75  * <code><i>string</i> namespace-uri(<i>node-set?</i>)</code>
76  * </p>
77  *
78  * <blockquote SRC="http://www.w3.org/TR/xpath">
79  * <p>
80  * The <b>namespace-uri</b>
81  * function returns the namespace URI of the <a
82  * HREF="http://www.w3.org/TR/xpath#dt-expanded-name" target="_top">expanded-name</a> of the node in the
83  * argument node-set that is first in <a
84  * HREF="http://www.w3.org/TR/xpath#dt-document-order" target="_top">document order</a>. If the argument
85  * node-set is empty, the first node has no <a
86  * HREF="http://www.w3.org/TR/xpath#dt-expanded-name" target="_top">expanded-name</a>, or the namespace URI of
87  * the <a HREF="http://www.w3.org/TR/xpath#dt-expanded-name" target="_top">expanded-name</a> is null, an empty
88  * string is returned. If the argument is omitted, it defaults to a
89  * node-set with the context node as its only member.
90  * </p>
91  *
92  * <blockquote> <b>NOTE: </b>The string returned by the <b>namespace-uri</b> function will
93  * be empty except for element nodes and attribute nodes.</blockquote>
94  *
95  * </blockquote>
96  *
97  * @author bob mcwhirter (bob @ werken.com)
98  * @see <a HREF="http://www.w3.org/TR/xpath#function-namespace-uri"
99  * target="_top">Section 4.1 of the XPath Specification</a>
100  */
101 public class NamespaceUriFunction implements Function
102 {
103
104     /**
105      * Create a new <code>NamespaceUriFunction</code> object.
106      */
107     public NamespaceUriFunction() {}
108
109     /**
110      * Returns the namespace URI of the specified node or the namespace URI of the context node if
111      * no arguments are provided.
112      *
113      * @param context the context at the point in the
114      * expression where the function is called
115      * @param args a <code>List</code> containing zero or one items
116      *
117      * @return a <code>String</code> containing the namespace URI
118      *
119      * @throws FunctionCallException if <code>args</code> has more than one item
120      */
121     public Object JavaDoc call(Context context,
122                        List JavaDoc args) throws FunctionCallException
123     {
124         if (args.size() == 0)
125         {
126             return evaluate( context.getNodeSet(),
127                              context.getNavigator() );
128         }
129
130         if ( args.size() == 1 )
131         {
132             return evaluate( args,
133                              context.getNavigator() );
134         }
135
136         throw new FunctionCallException( "namespace-uri() requires zero or one argument." );
137     }
138
139     /**
140      * Returns the namespace URI of <code>list.get(0)</code>
141      *
142      * @param list a list of nodes
143      * @param nav the <code>Navigator</code> used to retrieve the namespace
144      *
145      * @return the namespace URI of <code>list.get(0)</code>
146      *
147      * @throws FunctionCallException if <code>list.get(0)</code> is not a node
148      */
149     public static String JavaDoc evaluate(List JavaDoc list,
150                                   Navigator nav) throws FunctionCallException
151     {
152         if ( ! list.isEmpty() )
153         {
154             Object JavaDoc first = list.get(0);
155
156             if ( first instanceof List JavaDoc )
157             {
158                 return evaluate( (List JavaDoc) first,
159                                  nav );
160             }
161             else if ( nav.isElement( first ) )
162             {
163                 return nav.getElementNamespaceUri( first );
164             }
165             else if ( nav.isAttribute( first ) )
166             {
167                 String JavaDoc uri = nav.getAttributeNamespaceUri( first );
168                 if (uri == null) return "";
169                 return uri;
170             }
171             else if ( nav.isProcessingInstruction( first ) )
172             {
173                 return "";
174             }
175             else if ( nav.isNamespace( first ) )
176             {
177                 return "";
178             }
179             else if ( nav.isDocument( first ) )
180             {
181                 return "";
182             }
183             else if ( nav.isComment( first ) )
184             {
185                 return "";
186             }
187             else if ( nav.isText( first ) )
188             {
189                 return "";
190             }
191             else {
192                 throw new FunctionCallException(
193                   "The argument to the namespace-uri function must be a node-set");
194             }
195
196         }
197
198         return "";
199
200     }
201 }
202
203
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