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Java > Open Source Codes > proguard > classfile > visitor > ClassPresenceFilter


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.classfile.visitor;
22
23 import proguard.classfile.*;
24
25 /**
26  * This <code>ClassVisitor</code> delegates its visits to one of two
27  * <code>ClassVisitor</code> instances, depending on whether the name of
28  * the visited class file is present in a given <code>ClassPool</code> or not.
29  *
30  * @author Eric Lafortune
31  */
32 public class ClassPresenceFilter implements ClassVisitor
33 {
34     private ClassPool classPool;
35     private ClassVisitor presentClassVisitor;
36     private ClassVisitor missingClassVisitor;
37
38
39     /**
40      * Creates a new ClassPresenceFilter.
41      * @param classPool the <code>ClassPool</code> in which the
42      * presence will be tested.
43      * @param presentClassVisitor the <code>ClassVisitor</code> to which visits
44      * of present class files will be delegated.
45      * @param missingClassVisitor the <code>ClassVisitor</code> to which visits
46      * of missing class files will be delegated.
47      */
48     public ClassPresenceFilter(ClassPool classPool,
49                                ClassVisitor presentClassVisitor,
50                                ClassVisitor missingClassVisitor)
51     {
52         this.classPool = classPool;
53         this.presentClassVisitor = presentClassVisitor;
54         this.missingClassVisitor = missingClassVisitor;
55     }
56
57
58     // Implementations for ClassVisitor.
59
60     public void visitProgramClass(ProgramClass programClass)
61     {
62         ClassVisitor classFileVisitor = classFileVisitor(programClass);
63
64         if (classFileVisitor != null)
65         {
66             classFileVisitor.visitProgramClass(programClass);
67         }
68     }
69
70
71     public void visitLibraryClass(LibraryClass libraryClass)
72     {
73         ClassVisitor classFileVisitor = classFileVisitor(libraryClass);
74
75         if (classFileVisitor != null)
76         {
77             classFileVisitor.visitLibraryClass(libraryClass);
78         }
79     }
80
81
82     // Small utility methods.
83
84     /**
85      * Returns the appropriate <code>ClassVisitor</code>.
86      */
87     private ClassVisitor classFileVisitor(Clazz clazz)
88     {
89         return classPool.getClass(clazz.getName()) != null ?
90             presentClassVisitor :
91             missingClassVisitor;
92     }
93 }
94
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