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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/FloorFunction.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: FloorFunction.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  import org.jaxen.Navigator;
71  
72  /***
73   * <p><b>4.4</b> <code><i>number</i> floor(<i>number</i>)</code> 
74   * 
75   * 
76   * <blockquote src="http://www.w3.org/TR/xpath">
77   * The floor function returns the largest (closest to positive infinity) 
78   * number that is not greater than the argument and that is an integer....
79   * If the argument is NaN, then NaN is returned. 
80   * If the argument is positive infinity, then positive infinity is returned. 
81   * If the argument is negative infinity, then negative infinity is returned. 
82   * If the argument is positive zero, then positive zero is returned. 
83   * If the argument is negative zero, then negative zero is returned. 
84   * If the argument is greater than zero, but less than 1, then positive zero is returned.
85   * </blockquote>
86   * 
87   * @author bob mcwhirter (bob @ werken.com)
88   * 
89   * @see <a href="http://www.w3.org/TR/xpath#function-floor" target="_top">Section 4.4 of the XPath Specification</a>
90   * @see <a href="http://www.w3.org/1999/11/REC-xpath-19991116-errata/"  target="_top">XPath Errata</a>
91   */
92  public class FloorFunction implements Function
93  {
94  
95      /***
96       * Create a new <code>FloorFunction</code> object.
97       */
98      public FloorFunction() {}
99      
100     /*** Returns the largest integer less than or equal to a number.
101      *
102      * @param context the context at the point in the
103      *         expression when the function is called
104      * @param args a list with exactly one item which will be converted to a 
105      *     <code>Double</code> as if by the XPath <code>number()</code> function
106      * 
107      * @return a <code>Double</code> containing the largest integer less than or equal
108      *     to <code>args.get(0)</code>
109      * 
110      * @throws FunctionCallException if <code>args</code> has more or less than one item
111      */
112     public Object call(Context context,
113                        List args) throws FunctionCallException
114     {
115         if (args.size() == 1)
116         {
117             return evaluate( args.get(0),
118                              context.getNavigator() );
119         }
120 
121         throw new FunctionCallException( "floor() requires one argument." );
122     }
123 
124     /*** Returns the largest integer less than or equal 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 whose floor is returned
129      * @param nav ignored
130      * 
131      * @return a <code>Double</code> containing the largest integer less 
132      *     than or equal to <code>obj</code>
133      */
134     public static Double evaluate(Object obj,
135                                   Navigator nav)
136     {
137         Double value = NumberFunction.evaluate( obj,
138                                                 nav );
139 
140         return new Double( Math.floor( value.doubleValue() ) );
141     }
142 }
143