KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > net > sf > jga > fn > Visitable


1 // ============================================================================
2 // $Id: Visitable.java,v 1.4 2006/01/08 00:52:25 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;
34
35 /**
36  * Defines an interface for classes that may be interpreted by a Visitor.
37  * <p>
38  * jga uses the <a HREF="http://www.objectmentor.com/resources/articles/acv.pdf">AcyclicVisitor</a>
39  * pattern to provide a structure for implementing Visitor. Within jga, each
40  * class that implements Visitable provides a nested interface called Visitor
41  * that defines a <code>visit</code> method for the class. This is typically
42  * implemented with the following boilerplate:<br>
43  * <pre>
44  * public class Foo implements Visitable
45  * public void accept(net.sf.jga.fn.Visitor v) {
46  * if (v instanceof Foo.Visitor)
47  * ((Foo.Visitor)v).visit(this);
48         else
49             v.visit(this);
50  * }
51  *
52  * public interface Visitor extends net.sf.jga.fn.Visitor {
53  * public void visit(Foo host);
54  * }
55  * </pre>
56  * <p>
57  * Copyright &copy; 2002-2005 David A. Hall
58  *
59  * @author <a HREF="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
60  **/
61
62 public interface Visitable {
63     /**
64      * Determine if the visitor is appropriate (typically by testing against
65      * a specific interface) and if so, call pass the implementing object to
66      * the visitor's visit method.
67      */
68     public void accept(Visitor visitor);
69 }
70
Popular Tags