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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/LocalNameFunction.java,v 1.14 2006/02/05 21:47:41 elharo Exp $
3    * $Revision: 1.14 $
4    * $Date: 2006/02/05 21:47:41 $
5    *
6    * ====================================================================
7    *
8    * Copyright 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 are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: LocalNameFunction.java,v 1.14 2006/02/05 21:47:41 elharo Exp $
46   */
47  
48  
49  package org.jaxen.function;
50  
51  import java.util.List;
52  
53  import org.jaxen.Context;
54  import org.jaxen.Function;
55  import org.jaxen.FunctionCallException;
56  import org.jaxen.Navigator;
57  
58  /***
59   *   <p><b>4.1</b> <code><i>string</i> local-name(<i>node-set?</i>)</code></p> 
60   *  
61   * 
62   * <blockquote src="http://www.w3.org/TR/xpath">
63   * The <b>local-name</b> function returns the local part of the 
64   * expanded-name of the node in the argument node-set that is first in document order. 
65   * If the argument node-set is empty or the first node has no expanded-name, an 
66   * empty string is returned. If the argument is omitted, it defaults to a node-set with the context node as its only member.
67   *
68   * </blockquote>
69   * 
70   * @author bob mcwhirter (bob @ werken.com)
71   * @see <a href="http://www.w3.org/TR/xpath#function-local-name" target="_top">Section 4.1 of the XPath Specification</a>
72   */
73  public class LocalNameFunction implements Function
74  {
75      
76      /***
77       * Create a new <code>LocalNameFunction</code> object.
78       */
79      public LocalNameFunction() {}
80      
81      /***
82       * Returns the local-name of the specified node or the context node if 
83       * no arguments are provided.
84       * 
85       * @param context the context at the point in the
86       *         expression where the function is called
87       * @param args a <code>List</code> containing zero or one items
88       * 
89       * @return a <code>String</code> containing the local-name
90       * 
91       * @throws FunctionCallException if <code>args</code> has more than one item
92       */
93      public Object call(Context context,
94                         List args) throws FunctionCallException
95      {
96          if ( args.size() == 0 )
97          {
98              return evaluate( context.getNodeSet(),
99                               context.getNavigator() ); 
100         }
101 
102         if ( args.size() == 1 )
103         {
104             return evaluate( args,
105                              context.getNavigator() );
106         }
107 
108         throw new FunctionCallException( "local-name() requires zero or one argument." );
109     }
110 
111     /***
112      * Returns the local-name of <code>list.get(0)</code>
113      * 
114      * @param list a list of nodes
115      * @param nav the <code>Navigator</code> used to retrieve the local name
116      * 
117      * @return the local-name of <code>list.get(0)</code>
118      * 
119      * @throws FunctionCallException if <code>list.get(0)</code> is not a node
120      */
121     public static String evaluate(List list,
122                                   Navigator nav) throws FunctionCallException
123     {
124         if ( ! list.isEmpty() )
125         {            
126             Object first = list.get(0);
127 
128             if (first instanceof List)
129             {
130                 return evaluate( (List) first,
131                                  nav );
132             }
133             else if ( nav.isElement( first ) )
134             {
135                 return nav.getElementName( first );
136             }
137             else if ( nav.isAttribute( first ) )
138             {
139                 return nav.getAttributeName( first );
140             }
141             else if ( nav.isProcessingInstruction( first ) )
142             {
143                 return nav.getProcessingInstructionTarget( first );
144             }
145             else if ( nav.isNamespace( first ) )
146             {
147                 return nav.getNamespacePrefix( first );
148             }
149             else if ( nav.isDocument( first ) )
150             {
151                 return "";
152             }
153             else if ( nav.isComment( first ) )
154             {
155                 return "";
156             }
157             else if ( nav.isText( first ) )
158             {
159                 return "";
160             }
161             else {
162                 throw new FunctionCallException("The argument to the local-name function must be a node-set");   
163             }
164         }
165 
166         return "";
167     }
168     
169 }
170