01: /*
02: * ProGuard -- shrinking, optimization, obfuscation, and preverification
03: * of Java bytecode.
04: *
05: * Copyright (c) 2002-2003 Eric Lafortune (eric@graphics.cornell.edu)
06: *
07: * This program is free software; you can redistribute it and/or modify it
08: * under the terms of the GNU General Public License as published by the Free
09: * 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.optimize;
22:
23: import proguard.classfile.*;
24: import proguard.classfile.util.MethodLinker;
25: import proguard.classfile.visitor.*;
26:
27: /**
28: * This <code>ClassVisitor</code> and <code>MemberVisitor</code>
29: * marks classes and class members it visits. The marked elements
30: * will remain unchanged as necessary in the optimization step.
31: *
32: * @author Eric Lafortune
33: */
34: public class KeepMarker implements ClassVisitor, MemberVisitor {
35: // A visitor info flag to indicate the visitor accepter is being kept.
36: private static final Object KEPT = new Object();
37:
38: // Implementations for ClassVisitor.
39:
40: public void visitProgramClass(ProgramClass programClass) {
41: markAsKept(programClass);
42: }
43:
44: public void visitLibraryClass(LibraryClass libraryClass) {
45: markAsKept(libraryClass);
46: }
47:
48: // Implementations for MemberVisitor.
49:
50: public void visitProgramField(ProgramClass programClass,
51: ProgramField programField) {
52: markAsKept(programField);
53: }
54:
55: public void visitProgramMethod(ProgramClass programClass,
56: ProgramMethod programMethod) {
57: markAsKept(MethodLinker.lastMember(programMethod));
58: }
59:
60: public void visitLibraryField(LibraryClass libraryClass,
61: LibraryField libraryField) {
62: markAsKept(libraryField);
63: }
64:
65: public void visitLibraryMethod(LibraryClass libraryClass,
66: LibraryMethod libraryMethod) {
67: markAsKept(MethodLinker.lastMember(libraryMethod));
68: }
69:
70: // Small utility methods.
71:
72: private static void markAsKept(VisitorAccepter visitorAccepter) {
73: visitorAccepter.setVisitorInfo(KEPT);
74: }
75:
76: public static boolean isKept(VisitorAccepter visitorAccepter) {
77: return MethodLinker.lastVisitorAccepter(visitorAccepter)
78: .getVisitorInfo() == KEPT;
79: }
80: }
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