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Java > Open Source Codes > proguard > shrink > UsedClassFilter


1 /*
2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
3  * of Java bytecode.
4  *
5  * Copyright (c) 2002-2007 Eric Lafortune (eric@graphics.cornell.edu)
6  *
7  * This program is free software; you can redistribute it and/or modify it
8  * under the terms of the GNU General Public License as published by the Free
9  * Software Foundation; either version 2 of the License, or (at your option)
10  * any later version.
11  *
12  * This program is distributed in the hope that it will be useful, but WITHOUT
13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15  * more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with this program; if not, write to the Free Software Foundation, Inc.,
19  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21 package proguard.shrink;
22
23 import proguard.classfile.*;
24 import proguard.classfile.visitor.*;
25
26 /**
27  * This ClassVisitor delegates all its method calls to another ClassVisitor,
28  * but only for Clazz objects that are marked as used.
29  *
30  * @see UsageMarker
31  *
32  * @author Eric Lafortune
33  */
34 public class UsedClassFilter
35 implements ClassVisitor
36 {
37     private UsageMarker usageMarker;
38     private ClassVisitor classVisitor;
39
40
41     /**
42      * Creates a new UsedClassFilter.
43      * @param usageMarker the usage marker that is used to mark the classes
44      * and class members.
45      * @param classVisitor the class visitor to which the visiting will be
46      * delegated.
47      */
48     public UsedClassFilter(UsageMarker usageMarker,
49                            ClassVisitor classVisitor)
50     {
51         this.usageMarker = usageMarker;
52         this.classVisitor = classVisitor;
53     }
54
55
56     // Implementations for ClassVisitor.
57
58     public void visitProgramClass(ProgramClass programClass)
59     {
60         if (usageMarker.isUsed(programClass))
61         {
62             classVisitor.visitProgramClass(programClass);
63         }
64     }
65
66
67     public void visitLibraryClass(LibraryClass libraryClass)
68     {
69         if (usageMarker.isUsed(libraryClass))
70         {
71             classVisitor.visitLibraryClass(libraryClass);
72         }
73     }
74 }
75
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