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


1 // ============================================================================
2 // $Id: CompoundUnary.java,v 1.4 2006/01/08 00:52:25 davidahall Exp $
3 // Copyright (c) 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.UnaryFunctor;
36
37 /**
38  * Executes two UnaryFunctors, returning the results of the second.
39  * <p>
40  * Copyright &copy; 2005 David A. Hall
41  */
42
43 public class CompoundUnary<T,R> extends UnaryFunctor<T,R> {
44     
45     static final long serialVersionUID = 3041907427002719706L;
46
47     // the first functor. Results of this functor are dropped
48 private UnaryFunctor<T,?> _fn1;
49
50     // the second functor. Results of this functor are returned.
51 private UnaryFunctor<T,R> _fn2;
52     
53     public CompoundUnary (UnaryFunctor<T,?> fn1, UnaryFunctor<T,R> fn2) {
54         if (fn1 == null || fn2 == null)
55             throw new IllegalArgumentException JavaDoc("Two functors are required");
56
57         _fn1 = fn1;
58         _fn2 = fn2;
59     }
60
61     
62     /**
63      * @return the first of the two nested functors
64      */
65     public UnaryFunctor<T,?> getFirstFunctor() { return _fn1; }
66
67     
68     /**
69      * @return the second of the two nested functors
70      */
71     public UnaryFunctor<T,R> getSecondFunctor() { return _fn2; }
72
73     
74     /**
75      * Executes both functors, returning the results of the second.
76      */
77     public R fn(T arg) {
78         _fn1.fn(arg);
79         return _fn2.fn(arg);
80     }
81
82     
83     /**
84      * Calls the Visitor's <code>visit(Constant)</code> method, if it
85      * implements the nested Visitor interface.
86      */
87     public void accept(net.sf.jga.fn.Visitor v) {
88         if (v instanceof CompoundUnary.Visitor)
89             ((CompoundUnary.Visitor)v).visit(this);
90         else
91             v.visit(this);
92     }
93     
94     // Object overrides
95
96     public String JavaDoc toString() {
97         return _fn1 +"," +_fn2;
98     }
99     
100      // AcyclicVisitor
101
102     /**
103      * Interface for classes that may interpret a <b>Constant</b> unaryFunctor.
104      */
105     public interface Visitor extends net.sf.jga.fn.Visitor {
106         public void visit(CompoundUnary host);
107     }
108 }
109
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