KeepMarker.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.MethodLinker;
25import proguard.classfile.visitor.*;
26
27
28/**
29 * This <code>ClassVisitor</code> and <code>MemberVisitor</code>
30 * marks classes and class members it visits. The marked elements
31 * will remain unchanged as necessary in the optimization step.
32 *
33 * @author Eric Lafortune
34 */
35public class KeepMarker
36implements   ClassVisitor,
37             MemberVisitor
38{
39    // A visitor info flag to indicate the visitor accepter is being kept.
40    private static final Object KEPT = new Object();
41
42
43    // Implementations for ClassVisitor.
44
45    public void visitProgramClass(ProgramClass programClass)
46    {
47        markAsKept(programClass);
48    }
49
50
51    public void visitLibraryClass(LibraryClass libraryClass)
52    {
53        markAsKept(libraryClass);
54    }
55
56
57    // Implementations for MemberVisitor.
58
59    public void visitProgramField(ProgramClass programClass, ProgramField programField)
60    {
61        markAsKept(programField);
62    }
63
64
65    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
66    {
67        markAsKept(MethodLinker.lastMember(programMethod));
68    }
69
70
71    public void visitLibraryField(LibraryClass libraryClass, LibraryField libraryField)
72    {
73        markAsKept(libraryField);
74    }
75
76
77    public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod)
78    {
79        markAsKept(MethodLinker.lastMember(libraryMethod));
80    }
81
82
83    // Small utility methods.
84
85    private static void markAsKept(VisitorAccepter visitorAccepter)
86    {
87        visitorAccepter.setVisitorInfo(KEPT);
88    }
89
90
91    public static boolean isKept(VisitorAccepter visitorAccepter)
92    {
93        return MethodLinker.lastVisitorAccepter(visitorAccepter).getVisitorInfo() == KEPT;
94    }
95}
96