View Javadoc

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   *
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: 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;
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 call(Context context,
122                        List 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 evaluate(List list,
150                                   Navigator nav) throws FunctionCallException
151     {
152         if ( ! list.isEmpty() )
153         {
154             Object first = list.get(0);
155 
156             if ( first instanceof List )
157             {
158                 return evaluate( (List) 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 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