1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2009 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 */
21package proguard.shrink;
22
23import proguard.classfile.*;
24import proguard.classfile.visitor.ClassVisitor;
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 */
34public class UsedClassFilter
35implements   ClassVisitor
36{
37    private final UsageMarker  usageMarker;
38    private final 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