WriteOnlyFieldFilter.java revision db267bc191f906f55eaef21a27110cce2ec57fdf 
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.optimize;
22
23import proguard.classfile.*;
24import proguard.classfile.util.SimplifiedVisitor;
25import proguard.classfile.visitor.MemberVisitor;
26import proguard.optimize.info.ReadWriteFieldMarker;
27
28/**
29 * This <code>MemberVisitor</code> delegates its visits to program fields to
30 * other given <code>MemberVisitor</code> instances, but only when the visited
31 * field has been marked as write-only.
32 *
33 * @see ReadWriteFieldMarker
34 * @author Eric Lafortune
35 */
36public class WriteOnlyFieldFilter
37extends      SimplifiedVisitor
38implements   MemberVisitor
39{
40    private final MemberVisitor writeOnlyFieldVisitor;
41
42
43    /**
44     * Creates a new WriteOnlyFieldFilter.
45     * @param writeOnlyFieldVisitor the <code>MemberVisitor</code> to which
46     *                              visits to write-only fields will be delegated.
47     */
48    public WriteOnlyFieldFilter(MemberVisitor writeOnlyFieldVisitor)
49    {
50        this.writeOnlyFieldVisitor = writeOnlyFieldVisitor;
51    }
52
53
54    // Implementations for MemberVisitor.
55
56    public void visitProgramField(ProgramClass programClass, ProgramField programField)
57    {
58
59        if (ReadWriteFieldMarker.isWritten(programField) &&
60            !ReadWriteFieldMarker.isRead(programField))
61        {
62            writeOnlyFieldVisitor.visitProgramField(programClass, programField);
63        }
64    }
65}
66