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


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 /**
27  * This <code>MemberVisitor</code> delegates its visits to another given
28  * <code>MemberVisitor</code>, but only when the visited member has the proper
29  * access flags.
30  * <p>
31  * If conflicting access flags (public/private/protected) are specified,
32  * having one of them set will be considered sufficient.
33  *
34  * @see ClassConstants
35  *
36  * @author Eric Lafortune
37  */
38 public class MemberAccessFilter
39 implements MemberVisitor
40 {
41     // A mask of conflicting access flags. These are interpreted in a special
42 // way if more of them are required at the same time. In that case, one
43 // of them being set is sufficient.
44 private static final int ACCESS_MASK =
45         ClassConstants.INTERNAL_ACC_PUBLIC |
46         ClassConstants.INTERNAL_ACC_PRIVATE |
47         ClassConstants.INTERNAL_ACC_PROTECTED;
48
49     private int requiredSetAccessFlags;
50     private int requiredUnsetAccessFlags;
51     private int requiredOneSetAccessFlags;
52     private MemberVisitor memberVisitor;
53
54
55     /**
56      * Creates a new MemberAccessFilter.
57      * @param requiredSetAccessFlags the class access flags that should be
58      * set.
59      * @param requiredUnsetAccessFlags the class access flags that should be
60      * unset.
61      * @param memberVisitor the <code>MemberVisitor</code> to
62      * which visits will be delegated.
63      */
64     public MemberAccessFilter(int requiredSetAccessFlags,
65                               int requiredUnsetAccessFlags,
66                               MemberVisitor memberVisitor)
67     {
68         this.requiredSetAccessFlags = requiredSetAccessFlags & ~ACCESS_MASK;
69         this.requiredUnsetAccessFlags = requiredUnsetAccessFlags;
70         this.requiredOneSetAccessFlags = requiredSetAccessFlags & ACCESS_MASK;
71         this.memberVisitor = memberVisitor;
72     }
73
74
75     // Implementations for MemberVisitor.
76
77     public void visitProgramField(ProgramClass programClass, ProgramField programField)
78     {
79         if (accepted(programField.getAccessFlags()))
80         {
81             memberVisitor.visitProgramField(programClass, programField);
82         }
83     }
84
85
86     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
87     {
88         if (accepted(programMethod.getAccessFlags()))
89         {
90             memberVisitor.visitProgramMethod(programClass, programMethod);
91         }
92     }
93
94
95     public void visitLibraryField(LibraryClass libraryClass, LibraryField libraryField)
96     {
97         if (accepted(libraryField.getAccessFlags()))
98         {
99             memberVisitor.visitLibraryField(libraryClass, libraryField);
100         }
101     }
102
103
104     public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod)
105     {
106         if (accepted(libraryMethod.getAccessFlags()))
107         {
108             memberVisitor.visitLibraryMethod(libraryClass, libraryMethod);
109         }
110     }
111
112
113     // Small utility methods.
114
115     private boolean accepted(int accessFlags)
116     {
117         return (requiredSetAccessFlags & ~accessFlags) == 0 &&
118                (requiredUnsetAccessFlags & accessFlags) == 0 &&
119                (requiredOneSetAccessFlags == 0 ||
120                (requiredOneSetAccessFlags & accessFlags) != 0);
121     }
122 }
123
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