1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/RoundFunction.java,v 1.10 2005/06/26 16:07:22 elharo Exp $
3 * $Revision: 1.10 $
4 * $Date: 2005/06/26 16:07:22 $
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: RoundFunction.java,v 1.10 2005/06/26 16:07:22 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>4.4</b> <code><i>number</i> round(<i>number</i>)</code> </p>
74 *
75 *
76 * <blockquote src="http://www.w3.org/TR/xpath">
77 * The <b>round</b> function returns the number that is closest to the argument and that is an integer.
78 * If there are two such numbers, then the one that is closest to positive infinity is returned.
79 * If the argument is NaN, then NaN is returned. If the argument is positive infinity, then positive infinity is returned.
80 * If the argument is negative infinity, then negative infinity is returned.
81 * If the argument is positive zero, then positive zero is returned.
82 * If the argument is negative zero, then negative zero is returned.
83 * If the argument is less than zero, but greater than or equal to -0.5, then negative zero is returned.
84 * </blockquote>
85 *
86 * @author bob mcwhirter (bob @ werken.com)
87 *
88 * @see <a href="http://www.w3.org/TR/xpath#function-round" target="_top">Section 4.4 of the XPath Specification</a>
89 */
90 public class RoundFunction implements Function
91 {
92
93 /***
94 * Create a new <code>RoundFunction</code> object.
95 */
96 public RoundFunction() {}
97
98
99 /*** Returns the nearest integer to the number.
100 *
101 * @param context the context at the point in the
102 * expression when the function is called
103 * @param args a list with exactly one item which will be converted to a
104 * <code>Double</code> as if by the XPath <code>number()</code> function
105 *
106 * @return a <code>Double</code> containing the integer nearest to
107 * <code>args.get(0)</code>
108 *
109 * @throws FunctionCallException if <code>args</code> has more or less than one item
110 */
111 public Object call(Context context,
112 List args) throws FunctionCallException
113 {
114 if (args.size() == 1)
115 {
116 return evaluate( args.get(0),
117 context.getNavigator() );
118 }
119
120 throw new FunctionCallException( "round() requires one argument." );
121 }
122
123 /***
124 * Returns the integer nearest to the argument.
125 * If necessary, the argument is first converted to a <code>Double</code>
126 * as if by the XPath <code>number()</code> function.
127 *
128 * @param obj the object to be rounded
129 * @param nav ignored
130 *
131 * @return the integer nearest to <code>obj</code>
132 */
133 public static Double evaluate(Object obj,
134 Navigator nav)
135 {
136 Double d = NumberFunction.evaluate( obj,
137 nav );
138
139 if (d.isNaN() || d.isInfinite())
140 {
141 return d;
142 }
143
144 double value = d.doubleValue();
145 return new Double( Math.round( value ) );
146 }
147 }