1 /*
2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
3  *             of Java bytecode.
4  *
5  * Copyright (c) 2002-2014 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.attribute.visitor.AttributeVisitor;
25 import proguard.classfile.editor.MethodInvocationFixer;
26 import proguard.classfile.util.SimplifiedVisitor;
27 import proguard.classfile.visitor.MemberVisitor;
28 import proguard.optimize.info.ParameterUsageMarker;
29 import proguard.optimize.peephole.VariableShrinker;
30 
31 /**
32  * This MemberVisitor makes all methods that it visits static, if their 'this'
33  * parameters are unused.
34  *
35  * @see ParameterUsageMarker
36  * @see MethodInvocationFixer
37  * @see VariableShrinker
38  * @author Eric Lafortune
39  */
40 public class MethodStaticizer
41 extends      SimplifiedVisitor
42 implements   MemberVisitor,
43              AttributeVisitor
44 {
45     private final MemberVisitor extraStaticMemberVisitor;
46 
47 
48     /**
49      * Creates a new MethodStaticizer.
50      */
MethodStaticizer()51     public MethodStaticizer()
52     {
53         this(null);
54     }
55 
56 
57     /**
58      * Creates a new MethodStaticizer with an extra visitor.
59      * @param extraStaticMemberVisitor an optional extra visitor for all
60      *                                 methods that have been made static.
61      */
MethodStaticizer(MemberVisitor extraStaticMemberVisitor)62     public MethodStaticizer(MemberVisitor extraStaticMemberVisitor)
63     {
64         this.extraStaticMemberVisitor = extraStaticMemberVisitor;
65     }
66 
67 
68     // Implementations for MemberVisitor.
69 
visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)70     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
71     {
72         // Is the 'this' parameter being used?
73         if (!ParameterUsageMarker.isParameterUsed(programMethod, 0))
74         {
75             // Make the method static.
76             programMethod.u2accessFlags =
77                 (programMethod.getAccessFlags() & ~ClassConstants.ACC_FINAL) |
78                 ClassConstants.ACC_STATIC;
79 
80             // Visit the method, if required.
81             if (extraStaticMemberVisitor != null)
82             {
83                 extraStaticMemberVisitor.visitProgramMethod(programClass, programMethod);
84             }
85         }
86     }
87 }
88