1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/RoundFunction.java,v 1.12 2006/02/05 21:47:41 elharo Exp $
3 * $Revision: 1.12 $
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: RoundFunction.java,v 1.12 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>4.4</b> <code><i>number</i> round(<i>number</i>)</code> </p>
60 *
61 *
62 * <blockquote src="http://www.w3.org/TR/xpath">
63 * The <b>round</b> function returns the number that is closest to the argument and that is an integer.
64 * If there are two such numbers, then the one that is closest to positive infinity is returned.
65 * If the argument is NaN, then NaN is returned. If the argument is positive infinity, then positive infinity is returned.
66 * If the argument is negative infinity, then negative infinity is returned.
67 * If the argument is positive zero, then positive zero is returned.
68 * If the argument is negative zero, then negative zero is returned.
69 * If the argument is less than zero, but greater than or equal to -0.5, then negative zero is returned.
70 * </blockquote>
71 *
72 * @author bob mcwhirter (bob @ werken.com)
73 *
74 * @see <a href="http://www.w3.org/TR/xpath#function-round" target="_top">Section 4.4 of the XPath Specification</a>
75 */
76 public class RoundFunction implements Function
77 {
78
79 /***
80 * Create a new <code>RoundFunction</code> object.
81 */
82 public RoundFunction() {}
83
84
85 /*** Returns the nearest integer to the number.
86 *
87 * @param context the context at the point in the
88 * expression when the function is called
89 * @param args a list with exactly one item which will be converted to a
90 * <code>Double</code> as if by the XPath <code>number()</code> function
91 *
92 * @return a <code>Double</code> containing the integer nearest to
93 * <code>args.get(0)</code>
94 *
95 * @throws FunctionCallException if <code>args</code> has more or less than one item
96 */
97 public Object call(Context context,
98 List args) throws FunctionCallException
99 {
100 if (args.size() == 1)
101 {
102 return evaluate( args.get(0),
103 context.getNavigator() );
104 }
105
106 throw new FunctionCallException( "round() requires one argument." );
107 }
108
109 /***
110 * Returns the integer nearest to the argument.
111 * If necessary, the argument is first converted to a <code>Double</code>
112 * as if by the XPath <code>number()</code> function.
113 *
114 * @param obj the object to be rounded
115 * @param nav ignored
116 *
117 * @return the integer nearest to <code>obj</code>
118 */
119 public static Double evaluate(Object obj,
120 Navigator nav)
121 {
122 Double d = NumberFunction.evaluate( obj,
123 nav );
124
125 if (d.isNaN() || d.isInfinite())
126 {
127 return d;
128 }
129
130 double value = d.doubleValue();
131 return new Double( Math.round( value ) );
132 }
133 }