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


1 // ============================================================================
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// $Id: Distribute.java,v 1.8 2006/01/08 00:52:25 davidahall Exp $
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// Copyright (c) 2002-2005 David A. Hall
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// ============================================================================
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// The contents of this file are subject to the Common Development and
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// Distribution License (CDDL), Version 1.0 (the License); you may not use this
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// file except in compliance with the License. You should have received a copy
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// of the the License along with this file: if not, a copy of the License is
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// available from Sun Microsystems, Inc.
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//
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// http://www.sun.com/cddl/cddl.html
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//
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// From time to time, the license steward (initially Sun Microsystems, Inc.) may
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// publish revised and/or new versions of the License. You may not use,
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// distribute, or otherwise make this file available under subsequent versions
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// of the License.
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//
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// Alternatively, the contents of this file may be used under the terms of the
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// GNU Lesser General Public License Version 2.1 or later (the "LGPL"), in which
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// case the provisions of the LGPL are applicable instead of those above. If you
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// wish to allow use of your version of this file only under the terms of the
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// LGPL, and not to allow others to use your version of this file under the
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// terms of the CDDL, indicate your decision by deleting the provisions above
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// and replace them with the notice and other provisions required by the LGPL.
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// If you do not delete the provisions above, a recipient may use your version
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// of this file under the terms of either the CDDL or the LGPL.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// ============================================================================
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  * Binary Functor that passes its two arguments to two inner Unary Functors,
40  * and uses the results as arguments to an outer Binary Functor. This allows
41  * for the construction of compound functors from the primitives found in the
42  * arithmetic, logical, property, and comparison packages.
43  * <p>
44  * Copyright &copy; 2003-2005 David A. Hall
45  *
46  * @author <a HREF="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
47  **/

48
49 public class Distribute<T1,T2,F1,F2,R> extends BinaryFunctor<T1,T2,R> {
50
51     static final long serialVersionUID = -8288483375404557210L;
52
53     // The functor to which the first arg is passed
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private UnaryFunctor<T1,F1> _f;
55
56     // The functor to which the second arg is passed
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private UnaryFunctor<T2,F2> _g;
58
59     // The functor that evaluates the results of the two inner functors
60
private BinaryFunctor<F1,F2,R> _h;
61
62     /**
63      * Builds a Distribute functor, given two inner functors <b>f</b> and
64      * <b>g</b>, and outer functor <b>h</b>.
65      * @throws IllegalArgumentException if any of the functors is missing
66      */

67     public Distribute(UnaryFunctor<T1,F1> f,
68                       UnaryFunctor<T2,F2> g,
69                       BinaryFunctor<F1,F2,R> h)
70     {
71         if (f == null || g == null || h == null) {
72             throw new IllegalArgumentException JavaDoc("Three functors are required");
73         }
74         
75         _f = f; _g =g; _h = h;
76     }
77
78     /**
79      * Returns the first of two inner functors
80      * @return the first of two inner functors
81      */

82     public UnaryFunctor<T1,F1> getFirstInnerFunctor() { return _f; }
83
84     /**
85      * Returns the second of two inner functors
86      * @return the second of two inner functors
87      */

88     public UnaryFunctor<T2,F2> getSecondInnerFunctor() { return _g; }
89
90     /**
91      * Returns the outer functor
92      * @return the outer functor
93      */

94     public BinaryFunctor<F1,F2,R> getOuterFunctor() { return _h; }
95
96     // BinaryFunctor interface
97

98     /**
99      * Passes arguments <b>x</b> and <b>y</b> to the corresponding inner
100      * functors, and passes the results of those functors to the outer functor.
101      *
102      * @return h(f(x), g(y))
103      */

104     public R fn(T1 x, T2 y) {
105         return _h.fn(_f.fn(x), _g.fn(y));
106     }
107     
108     /**
109      * Calls the Visitor's <code>visit(Distribute)</code> method, if it
110      * implements the nested Visitor interface.
111      */

112     public void accept(net.sf.jga.fn.Visitor v) {
113         if (v instanceof Distribute.Visitor)
114             ((Distribute.Visitor)v).visit(this);
115         else
116             v.visit(this);
117     }
118
119     // Object overrides
120

121     public String JavaDoc toString() {
122         return _h+".distribute("+_f+","+_g+")";
123     }
124     
125     // Acyclic Visitor
126

127     /**
128      * Interface for classes that may interpret a <b>Distribute</b> functor.
129      */

130     public interface Visitor extends net.sf.jga.fn.Visitor {
131         public void visit(Distribute host);
132     }
133 }
134
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