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


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 JavaDoc;
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 JavaDoc call(Context context,
112                        List JavaDoc 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 JavaDoc evaluate(Object JavaDoc obj,
134                                   Navigator nav)
135     {
136         Double JavaDoc 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 JavaDoc( Math.round( value ) );
146     }
147 }
148
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