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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NameFunction.java,v 1.11 2006/02/05 21:47:41 elharo Exp $
3    * $Revision: 1.11 $
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: NameFunction.java,v 1.11 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> name(<i>node-set?</i>)</code> </p>
60   *  
61   * 
62   * <blockquote src="http://www.w3.org/TR/xpath">
63   * The <b>name</b> function returns a string containing a QName representing 
64   * the expanded-name of the node in the argument node-set that is first in document order. 
65   * The QName must represent the expanded-name with respect to the namespace declarations 
66   * in effect on the node whose expanded-name is being represented. Typically, this will 
67   * be the QName that occurred in the XML source....If 
68   * the argument node-set is empty or the first node has 
69   * no expanded-name, an empty string is returned. 
70   * If the argument it omitted, it defaults to a node-set with the context node as its only member.
71   * </blockquote>
72   * 
73   * @author bob mcwhirter (bob @ werken.com)
74   * 
75   * @see <a href="http://www.w3.org/TR/xpath#function-name" target="_top">Section 4.1 of the XPath Specification</a>
76   */
77  public class NameFunction implements Function
78  {
79      
80      
81      /***
82       * Create a new <code>NameFunction</code> object.
83       */
84      public NameFunction() {}
85      
86      /***
87       * Returns the name of the specified node or the name of the context node if 
88       * no arguments are provided.
89       * 
90       * @param context the context at the point in the
91       *         expression where the function is called
92       * @param args a <code>List</code> containing zero or one items
93       * 
94       * @return a <code>String</code> containing the name
95       * 
96       * @throws FunctionCallException if <code>args</code> has more than one item
97       */
98      public Object call(Context context,
99                         List args) throws FunctionCallException
100     {
101         if ( args.size() == 0 )
102         {
103             return evaluate( context.getNodeSet(),
104                              context.getNavigator() );
105         }
106 
107         if ( args.size() == 1 )
108         {
109             return evaluate( args,
110                              context.getNavigator() );
111         }
112 
113         throw new FunctionCallException( "name() requires zero or one argument." );
114     }
115 
116     /***
117      * Returns the name of <code>list.get(0)</code>
118      * 
119      * @param list a list of nodes
120      * @param nav the <code>Navigator</code> used to retrieve the name
121      * 
122      * @return the name of <code>list.get(0)</code>
123      * 
124      * @throws FunctionCallException if <code>list.get(0)</code> is not a node
125      */
126     public static String evaluate(List list,
127                                   Navigator nav) throws FunctionCallException
128     {
129         if ( ! list.isEmpty() )
130         {            
131             Object first = list.get(0);
132 
133             if (first instanceof List)
134             {
135                 return evaluate( (List) first,
136                                  nav );
137             }
138             else if ( nav.isElement( first ) )
139             {
140                 return nav.getElementQName( first );
141             }
142             else if ( nav.isAttribute( first ) )
143             {
144                 return nav.getAttributeQName( first );
145             }
146             else if ( nav.isProcessingInstruction( first ) )
147             {
148                 return nav.getProcessingInstructionTarget( first );
149             }
150             else if ( nav.isNamespace( first ) )
151             {
152                 return nav.getNamespacePrefix( first );
153             }
154             else if ( nav.isDocument( first ) )
155             {
156                 return "";
157             }
158             else if ( nav.isComment( first ) )
159             {
160                 return "";
161             }
162             else if ( nav.isText( first ) )
163             {
164                 return "";
165             }
166             else {
167                 throw new FunctionCallException("The argument to the name function must be a node-set");   
168             }
169         }
170 
171         return "";
172 
173     }
174     
175 }