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Java > Open Source Codes > proguard > optimize > KeepMarker


1 /*
2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
3  * of Java bytecode.
4  *
5  * Copyright (c) 2002-2003 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  */
21 package proguard.optimize;
22
23 import proguard.classfile.*;
24 import proguard.classfile.util.MethodLinker;
25 import 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  */
35 public class KeepMarker
36 implements ClassVisitor,
37              MemberVisitor
38 {
39     // A visitor info flag to indicate the visitor accepter is being kept.
40 private static final Object JavaDoc KEPT = new Object JavaDoc();
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
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