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


1 /*
2  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NotFunction.java,v 1.7 2005/06/26 16:07:22 elharo Exp $
3  * $Revision: 1.7 $
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: NotFunction.java,v 1.7 2005/06/26 16:07:22 elharo Exp $
60  */
61
62 package org.jaxen.function;
63
64 import java.util.List JavaDoc;
65
66 import org.jaxen.Context;
67 import org.jaxen.Function;
68 import org.jaxen.FunctionCallException;
69 import org.jaxen.Navigator;
70
71 /**
72  * <p><b>4.3</b> <code><i>boolean</i> not(<i>boolean</i>)</code> </p>
73  *
74  *
75  * <blockquote SRC="http://www.w3.org/TR/xpath#function-not">
76  * The <b>not</b> function returns true if its argument is false, and false otherwise.
77  * </blockquote>
78  *
79  * @author bob mcwhirter (bob @ werken.com)
80  * @see <a HREF="http://www.w3.org/TR/xpath#function-not" target="_top">Section 4.3 of the XPath Specification</a>
81  */
82 public class NotFunction implements Function
83 {
84
85     /**
86      * Create a new <code>NotFunction</code> object.
87      */
88     public NotFunction() {}
89     
90     /**
91      * Returns <code>Boolean.TRUE</code> if the boolean value of
92      * <code>args.get(0)</code> is false, and <code>Boolean.FALSE</code> otherwise.
93      * The boolean value is calculated as if by the XPath <code>boolean</code>
94      * function.
95      *
96      * @param context the context at the point in the
97      * expression where the function is called
98      * @param args a single element list
99      *
100      * @return <code>Boolean.TRUE</code> if the boolean value of
101      * <code>obj</code> is false, and <code>Boolean.FALSE</code> otherwise
102      *
103      * @throws FunctionCallException if <code>args</code> does not have exactly one argument
104      */
105     public Object JavaDoc call(Context context,
106                        List JavaDoc args) throws FunctionCallException
107     {
108         if (args.size() == 1)
109         {
110             return evaluate( args.get(0), context.getNavigator() );
111         }
112
113         throw new FunctionCallException( "not() requires one argument." );
114     }
115
116     /**
117      * Returns <code>Boolean.TRUE</code> if the boolean value of
118      * <code>obj</code> is false, and <code>Boolean.FALSE</code> otherwise.
119      * The boolean value is calculated as if by the XPath <code>boolean</code>
120      * function.
121      *
122      * @param obj the object whose boolean value is inverted
123      * @param nav the <code>Navigator</code> used to calculate the boolean value of <code>obj</code>
124      *
125      * @return <code>Boolean.TRUE</code> if the boolean value of
126      * <code>obj</code> is false, and <code>Boolean.FALSE</code> otherwise
127      */
128     public static Boolean JavaDoc evaluate(Object JavaDoc obj, Navigator nav)
129     {
130         return ( ( BooleanFunction.evaluate( obj, nav ).booleanValue() )
131                  ? Boolean.FALSE
132                  : Boolean.TRUE
133                  );
134     }
135     
136 }
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