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


1 // ============================================================================
2 // $Id: CompoundGenerator.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.Generator;
36
37 /**
38  * Executes two generators, returning the results of the second.
39  * <p>
40  * Copyright &copy; 2005 David A. Hall
41  */
42
43 public class CompoundGenerator<R> extends Generator<R> {
44
45     static final long serialVersionUID = -2654287117664423223L;
46
47     // the first generator. Results of this generator are dropped
48 private Generator<?> _gen1;
49
50     // the second generator. Results of this generator are returned.
51 private Generator<R> _gen2;
52     
53     public CompoundGenerator (Generator<?> gen1, Generator<R> gen2) {
54         if (gen1 == null || gen2 == null)
55             throw new IllegalArgumentException JavaDoc("Two generators are required");
56
57         _gen1 = gen1;
58         _gen2 = gen2;
59     }
60
61     
62     /**
63      * @return the first of the two nested functors
64      */
65     public Generator<?> getFirstFunctor() { return _gen1; }
66
67     
68     /**
69      * @return the second of the two nested functors
70      */
71     public Generator<R> getSecondFunctor() { return _gen2; }
72
73     
74     /**
75      * Executes both generators, returning the results of the second.
76      */
77     public R gen() {
78         _gen1.gen();
79         return _gen2.gen();
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 CompoundGenerator.Visitor)
89             ((CompoundGenerator.Visitor)v).visit(this);
90         else
91             v.visit(this);
92     }
93     
94     // Object overrides
95
96     public String JavaDoc toString() {
97         return _gen1 +"," +_gen2;
98     }
99     
100      // AcyclicVisitor
101
102     /**
103      * Interface for classes that may interpret a <b>Constant</b> generator.
104      */
105     public interface Visitor extends net.sf.jga.fn.Visitor {
106         public void visit(CompoundGenerator host);
107     }
108 }
109
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