1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2014 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.classfile.visitor;
22
23import 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 */
38public class MemberAccessFilter
39implements   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.ACC_PUBLIC  |
46        ClassConstants.ACC_PRIVATE |
47        ClassConstants.ACC_PROTECTED;
48
49    private final int           requiredSetAccessFlags;
50    private final int           requiredUnsetAccessFlags;
51    private final int           requiredOneSetAccessFlags;
52    private final 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