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Java > Open Source Codes > net > sf > jga > fn > adaptor > Bind2nd


1 // ============================================================================
2 // $Id: Bind2nd.java,v 1.12 2006/01/08 00:52:25 davidahall Exp $
3 // Copyright (c) 2003-2005 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.adaptor;
34
35 import net.sf.jga.fn.BinaryFunctor;
36 import net.sf.jga.fn.UnaryFunctor;
37
38 /**
39  * UnaryFunctor that wraps a given BinaryFunctor, passing a constant value
40  * as the second argument of the child functor. The runtime argument is passed
41  * as the first argument of the child functor.
42  * <p>
43  * Copyright &copy; 2003-2005 David A. Hall
44  *
45  * @author <a HREF="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
46  **/
47
48 public class Bind2nd<T1, T2, R> extends UnaryFunctor<T1, R> {
49
50     static final long serialVersionUID = -5977756270123944716L;
51     
52     // The functor whose second argument is bound
53 private BinaryFunctor<T1, T2, R> _f;
54     
55     // The value bound to the second arg
56 private T2 _c;
57
58     /**
59      * Builds a Bind2nd Functor with the given contant and child functor.
60      * @throws IllegalArgumentException if the functor is null.
61      */
62     public Bind2nd(T2 constant, BinaryFunctor<T1, T2, R> fn) {
63         if (fn == null) {
64             throw new IllegalArgumentException JavaDoc("Must supply a function");
65         }
66         _f = fn;
67         _c = constant;
68     }
69
70
71     /**
72      * Returns the child functor for this functor
73      * @return the child functor for this functor
74      */
75     public BinaryFunctor<T1, T2, R> getFunctor() { return _f; }
76     
77     /**
78      * Returns the constant value
79      * @return the constant value
80      */
81     public T2 getConstant() { return _c; }
82
83     // UnaryFunctor interface
84
85     /**
86      * Given one argument, passes the argument and the constant value to the
87      * child functor and returns the result.
88      *
89      * @return f(x,c)
90      */
91     public R fn(T1 x) {
92         return _f.fn(x, _c);
93     }
94
95     /**
96      * Calls the Visitor's <code>visit(Bind2nd)</code> method, if it
97      * implements the nested Visitor interface.
98      */
99     public void accept(net.sf.jga.fn.Visitor v) {
100         if (v instanceof Bind2nd.Visitor)
101             ((Bind2nd.Visitor)v).visit(this);
102         else
103             v.visit(this);
104     }
105     
106     // Object overrides
107
108     public String JavaDoc toString() {
109         return _f+".bind2nd("+_c+")";
110     }
111     
112     // AcyclicVisitor
113
114     /**
115      * Interface for classes that may interpret an <b>Bind2nd</b> functor.
116      */
117     public interface Visitor extends net.sf.jga.fn.Visitor {
118         public void visit(Bind2nd bf);
119     }
120 }
121
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