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


1 /*
2  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/PositionFunction.java,v 1.8 2005/06/26 16:07:23 elharo Exp $
3  * $Revision: 1.8 $
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: PositionFunction.java,v 1.8 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
71 /**
72  * <p><b>4.1</b> <code><i>number</i> position()</code></p>
73  *
74  *
75  * <blockquote SRC="http://www.w3.org/TR/xpath">
76  * The position function returns a number equal to the context position from the expression evaluation context.
77  * </blockquote>
78  *
79  * @author bob mcwhirter (bob @ werken.com)
80  * @see <a HREF="http://www.w3.org/TR/xpath#function-position" target="_top">Section 4.1 of the XPath Specification</a>
81  */
82 public class PositionFunction implements Function
83 {
84     
85     /**
86      * Create a new <code>PositionFunction</code> object.
87      */
88     public PositionFunction() {}
89     
90     /**
91      * Returns the position of the context node in the context node-set.
92      *
93      * @param context the context at the point in the
94      * expression where the function is called
95      * @param args an empty list
96      *
97      * @return a <code>Double</code> containing the context position
98      *
99      * @throws FunctionCallException if <code>args</code> is not empty
100      *
101      * @see Context#getSize()
102      */
103     public Object JavaDoc call(Context context, List JavaDoc args) throws FunctionCallException
104     {
105         if ( args.size() == 0 )
106         {
107             return evaluate( context );
108         }
109         
110         throw new FunctionCallException( "position() requires no arguments." );
111     }
112     
113     /**
114      *
115      * Returns the position of the context node in the context node-set.
116      *
117      * @param context the context at the point in the
118      * expression where the function is called
119      *
120      * @return a <code>Double</code> containing the context position
121      *
122      * @see Context#getPosition()
123      */
124     public static Double JavaDoc evaluate(Context context)
125     {
126         return new Double JavaDoc( context.getPosition() );
127     }
128     
129 }
130
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