NameFunction


1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NameFunction.java,v 1.9 2005/06/26 16:07:23 elharo Exp $
3    * $Revision: 1.9 $
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: NameFunction.java,v 1.9 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><b>4.1</b> <code><i>string</i> name(<i>node-set?</i>)</code> </p>
74   *  
75   * 
76   * <blockquote SRC="http://www.w3.org/TR/xpath">
77   * The <b>name</b> function returns a string containing a QName representing 
78   * the expanded-name of the node in the argument node-set that is first in document order. 
79   * The QName must represent the expanded-name with respect to the namespace declarations 
80   * in effect on the node whose expanded-name is being represented. Typically, this will 
81   * be the QName that occurred in the XML source....If 
82   * the argument node-set is empty or the first node has 
83   * no expanded-name, an empty string is returned. 
84   * If the argument it omitted, it defaults to a node-set with the context node as its only member.
85   * </blockquote>
86   * 
87   * @author bob mcwhirter (bob @ werken.com)
88   * 
89   * @see <a HREF="http://www.w3.org/TR/xpath#function-name" target="_top">Section 4.1 of the XPath Specification</a>
90   */
91  public class NameFunction implements Function
92  {
93      
94      
95      /**
96       * Create a new <code>NameFunction</code> object.
97       */
98      public NameFunction() {}
99      
100     /**
101      * Returns the name of the specified node or the name of the context node if 
102      * no arguments are provided.
103      * 
104      * @param context the context at the point in the
105      *         expression where the function is called
106      * @param args a <code>List</code> containing zero or one items
107      * 
108      * @return a <code>String</code> containing the name
109      * 
110      * @throws FunctionCallException if <code>args</code> has more than one item
111      */
112     public Object   call(Context context,
113                        List   args) throws FunctionCallException
114     {
115         if ( args.size() == 0 )
116         {
117             return evaluate( context.getNodeSet(),
118                              context.getNavigator() );
119         }
120 
121         if ( args.size() == 1 )
122         {
123             return evaluate( args,
124                              context.getNavigator() );
125         }
126 
127         throw new FunctionCallException( "name() requires zero or one argument." );
128     }
129 
130     /**
131      * Returns the name of <code>list.get(0)</code>
132      * 
133      * @param list a list of nodes
134      * @param nav the <code>Navigator</code> used to retrieve the name
135      * 
136      * @return the name of <code>list.get(0)</code>
137      * 
138      * @throws FunctionCallException if <code>list.get(0)</code> is not a node
139      */
140     public static String   evaluate(List   list,
141                                   Navigator nav) throws FunctionCallException
142     {
143         if ( ! list.isEmpty() )
144         {            
145             Object   first = list.get(0);
146 
147             if (first instanceof List  )
148             {
149                 return evaluate( (List  ) first,
150                                  nav );
151             }
152             else if ( nav.isElement( first ) )
153             {
154                 return nav.getElementQName( first );
155             }
156             else if ( nav.isAttribute( first ) )
157             {
158                 return nav.getAttributeQName( first );
159             }
160             else if ( nav.isProcessingInstruction( first ) )
161             {
162                 return nav.getProcessingInstructionTarget( first );
163             }
164             else if ( nav.isNamespace( first ) )
165             {
166                 return nav.getNamespacePrefix( first );
167             }
168             else if ( nav.isDocument( first ) )
169             {
170                 return "";
171             }
172             else if ( nav.isComment( first ) )
173             {
174                 return "";
175             }
176             else if ( nav.isText( first ) )
177             {
178                 return "";
179             }
180             else {
181                 throw new FunctionCallException("The argument to the name function must be a node-set");   
182             }
183         }
184 
185         return "";
186 
187     }
188     
189 }
190
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