ConstantMemberFilter.java revision 8a6199f0c36a778f22394364347a301b0b28e94b 
1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2013 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.optimize;
22
23import proguard.classfile.*;
24import proguard.classfile.util.SimplifiedVisitor;
25import proguard.classfile.visitor.MemberVisitor;
26import proguard.evaluation.value.Value;
27import proguard.optimize.evaluation.StoringInvocationUnit;
28
29/**
30 * This <code>MemberVisitor</code> delegates its visits to program class members
31 * to another given <code>MemberVisitor</code>, but only when the visited
32 * class member has been marked as a constant.
33 *
34 * @see StoringInvocationUnit
35 * @author Eric Lafortune
36 */
37public class ConstantMemberFilter
38extends      SimplifiedVisitor
39implements   MemberVisitor
40{
41    private final MemberVisitor constantMemberVisitor;
42
43
44    /**
45     * Creates a new ConstantMemberFilter.
46     * @param constantMemberVisitor the <code>MemberVisitor</code> to which
47     *                              visits to constant members will be delegated.
48     */
49    public ConstantMemberFilter(MemberVisitor constantMemberVisitor)
50    {
51        this.constantMemberVisitor = constantMemberVisitor;
52    }
53
54
55    // Implementations for MemberVisitor.
56
57    public void visitProgramField(ProgramClass programClass, ProgramField programField)
58    {
59        Value value = StoringInvocationUnit.getFieldValue(programField);
60        if (value != null &&
61            value.isParticular())
62        {
63            constantMemberVisitor.visitProgramField(programClass, programField);
64        }
65    }
66
67
68    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
69    {
70        Value value = StoringInvocationUnit.getMethodReturnValue(programMethod);
71        if (value != null &&
72            value.isParticular())
73        {
74            constantMemberVisitor.visitProgramMethod(programClass, programMethod);
75        }
76    }
77}
78