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Java > Open Source Codes > proguard > optimize > info > NoSideEffectMethodMarker


1 /*
2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
3  * of Java bytecode.
4  *
5  * Copyright (c) 2002-2007 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.info;
22
23 import proguard.classfile.*;
24 import proguard.classfile.util.*;
25 import proguard.classfile.visitor.MemberVisitor;
26
27 /**
28  * This MemberVisitor marks all methods that it visits as not having any side
29  * effects. It will make the SideEffectMethodMarker consider them as such
30  * without further analysis.
31  *
32  * @see SideEffectMethodMarker
33  * @author Eric Lafortune
34  */
35 public class NoSideEffectMethodMarker
36 extends SimplifiedVisitor
37 implements MemberVisitor
38 {
39     // A visitor info flag to indicate the visitor accepter is being kept,
40 // but that it doesn't have any side effects.
41 private static final Object JavaDoc KEPT_BUT_NO_SIDE_EFFECTS = new Object JavaDoc();
42
43
44     // Implementations for MemberVisitor.
45
46     public void visitAnyMember(Clazz Clazz, Member member)
47     {
48         // Ignore any attempts to mark fields.
49 }
50
51
52     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
53     {
54         markNoSideEffects(programMethod);
55     }
56
57
58     public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod)
59     {
60         markNoSideEffects(libraryMethod);
61     }
62
63
64     // Small utility methods.
65
66     private static void markNoSideEffects(Method method)
67     {
68         MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
69         if (info != null)
70         {
71             info.setNoSideEffects();
72         }
73         else
74         {
75             MethodLinker.lastMember(method).setVisitorInfo(KEPT_BUT_NO_SIDE_EFFECTS);
76         }
77     }
78
79
80     public static boolean hasNoSideEffects(Method method)
81     {
82         if (MethodLinker.lastVisitorAccepter(method).getVisitorInfo() == KEPT_BUT_NO_SIDE_EFFECTS)
83         {
84             return true;
85         }
86
87         MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
88         return info != null &&
89                info.hasNoSideEffects();
90     }
91 }
92
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