1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/PositionFunction.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: PositionFunction.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
57 /***
58 * <p><b>4.1</b> <code><i>number</i> position()</code></p>
59 *
60 *
61 * <blockquote src="http://www.w3.org/TR/xpath">
62 * The position function returns a number equal to the context position from the expression evaluation context.
63 * </blockquote>
64 *
65 * @author bob mcwhirter (bob @ werken.com)
66 * @see <a href="http://www.w3.org/TR/xpath#function-position" target="_top">Section 4.1 of the XPath Specification</a>
67 */
68 public class PositionFunction implements Function
69 {
70
71 /***
72 * Create a new <code>PositionFunction</code> object.
73 */
74 public PositionFunction() {}
75
76 /***
77 * Returns the position of the context node in the context node-set.
78 *
79 * @param context the context at the point in the
80 * expression where the function is called
81 * @param args an empty list
82 *
83 * @return a <code>Double</code> containing the context position
84 *
85 * @throws FunctionCallException if <code>args</code> is not empty
86 *
87 * @see Context#getSize()
88 */
89 public Object call(Context context, List args) throws FunctionCallException
90 {
91 if ( args.size() == 0 )
92 {
93 return evaluate( context );
94 }
95
96 throw new FunctionCallException( "position() does not take any arguments." );
97 }
98
99 /***
100 *
101 * Returns the position of the context node in the context node-set.
102 *
103 * @param context the context at the point in the
104 * expression where the function is called
105 *
106 * @return a <code>Double</code> containing the context position
107 *
108 * @see Context#getPosition()
109 */
110 public static Double evaluate(Context context)
111 {
112 return new Double( context.getPosition() );
113 }
114
115 }