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Java > Open Source Codes > net > sf > jga > fn > logical > BinaryNegate


1 // ============================================================================
2 // $Id: BinaryNegate.java,v 1.15 2006/08/07 03:32:31 davidahall Exp $
3 // Copyright (c) 2002-2005 David A. Hall
4 // ============================================================================
5 // The contents of this file are subject to the Common Development and
6 // Distribution License (CDDL), Version 1.0 (the License); you may not use this
7 // file except in compliance with the License. You should have received a copy
8 // of the the License along with this file: if not, a copy of the License is
9 // available from Sun Microsystems, Inc.
10 //
11 // http://www.sun.com/cddl/cddl.html
12 //
13 // From time to time, the license steward (initially Sun Microsystems, Inc.) may
14 // publish revised and/or new versions of the License. You may not use,
15 // distribute, or otherwise make this file available under subsequent versions
16 // of the License.
17 //
18 // Alternatively, the contents of this file may be used under the terms of the
19 // GNU Lesser General Public License Version 2.1 or later (the "LGPL"), in which
20 // case the provisions of the LGPL are applicable instead of those above. If you
21 // wish to allow use of your version of this file only under the terms of the
22 // LGPL, and not to allow others to use your version of this file under the
23 // terms of the CDDL, indicate your decision by deleting the provisions above
24 // and replace them with the notice and other provisions required by the LGPL.
25 // If you do not delete the provisions above, a recipient may use your version
26 // of this file under the terms of either the CDDL or the LGPL.
27 //
28 // This library is distributed in the hope that it will be useful,
29 // but WITHOUT ANY WARRANTY; without even the implied warranty of
30 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
31 // ============================================================================
32
33 package net.sf.jga.fn.logical;
34
35 import net.sf.jga.fn.BinaryPredicate;
36 import net.sf.jga.fn.BinaryFunctor;
37
38 /**
39  * Binary Predicate that logically negates the result of a child predicate.
40  * Returns true when child predicate <b>p</b> returns false given object
41  * arguments <b>x</b> and <b>y</b>.
42  * <p>
43  * Copyright &copy; 2002-2005 David A. Hall
44  *
45  * @author <a HREF="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
46  **/
47
48 public class BinaryNegate<T1, T2> extends BinaryPredicate<T1, T2> {
49
50     static final long serialVersionUID = 3005632919263334394L;
51     
52     private BinaryFunctor<? super T1, ? super T2, Boolean JavaDoc> _p;
53
54     /**
55      * Builds a BinaryNegate predicate wrapping the given Binary Predicate.
56      * @throws IllegalArgumentException when no child predicate is given
57      */
58     public BinaryNegate(BinaryFunctor<? super T1, ? super T2, Boolean JavaDoc> p) {
59         if (p == null) {
60             throw new IllegalArgumentException JavaDoc("Child Predicate may not be null");
61         }
62         
63         _p = p;
64     }
65
66     /**
67      * Returns the child predicate.
68      * @return the child predicate.
69      */
70     public BinaryFunctor<? super T1, ? super T2, Boolean JavaDoc> getPredicate() {
71         return _p;
72     }
73
74     // BinaryPredicate interface
75
76     /**
77      * Given arguments <b>x</b> and <b>y</b>, returns true when child
78      * predicate <b>p</b> returns false for x and y, otherwise returns true.
79      *
80      * @return !(p.p(x,y))
81      */
82     public Boolean JavaDoc fn(T1 x, T2 y) {
83         return ! _p.fn(x,y);
84     }
85     
86     /**
87      * Calls the Visitor's <code>visit(UnaryNegate)</code> method, if it
88      * implements the nested Visitor interface.
89      */
90     public void accept(net.sf.jga.fn.Visitor v) {
91         if (v instanceof BinaryNegate.Visitor)
92             ((BinaryNegate.Visitor)v).visit(this);
93         else
94             v.visit(this);
95     }
96
97     // Object overrides
98
99     public String JavaDoc toString() {
100         return "BinaryNegate("+_p+")";
101     }
102     
103     // Acyclic Visitor
104
105     /**
106      * Interface for classes that may interpret a <b>BinaryNegate</b>
107      * predicate.
108      */
109     public interface Visitor extends net.sf.jga.fn.Visitor {
110         public void visit(BinaryNegate host);
111     }
112 }
113
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