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;
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 call(Context context, List 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 evaluate(Context context)
125 {
126 return new Double( context.getPosition() );
127 }
128
129 }