RetargetedInnerClassAttributeRemover.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.peephole;
22
23import proguard.classfile.*;
24import proguard.classfile.attribute.*;
25import proguard.classfile.attribute.visitor.*;
26import proguard.classfile.constant.ClassConstant;
27import proguard.classfile.constant.visitor.ConstantVisitor;
28import proguard.classfile.util.SimplifiedVisitor;
29import proguard.classfile.visitor.ClassVisitor;
30
31/**
32 * This ClassVisitor removes InnerClasses and EnclosingMethod attributes in
33 * classes that are retargeted or that refer to classes that are retargeted.
34 *
35 * @see ClassMerger
36 * @author Eric Lafortune
37 */
38public class RetargetedInnerClassAttributeRemover
39extends      SimplifiedVisitor
40implements   ClassVisitor,
41             AttributeVisitor,
42             InnerClassesInfoVisitor,
43             ConstantVisitor
44{
45    private boolean retargeted;
46
47
48    // Implementations for ClassVisitor.
49
50    public void visitProgramClass(ProgramClass programClass)
51    {
52        int         attributesCount = programClass.u2attributesCount;
53        Attribute[] attributes      = programClass.attributes;
54
55        int newAtributesCount = 0;
56
57        // Copy over all non-retargeted attributes.
58        for (int index = 0; index < attributesCount; index++)
59        {
60            Attribute attribute = attributes[index];
61
62            // Check if it's an InnerClasses or EnclosingMethod attribute in
63            // a retargeted class or referring to a retargeted class.
64            retargeted = false;
65            attribute.accept(programClass, this);
66            if (!retargeted)
67            {
68                attributes[newAtributesCount++] = attribute;
69            }
70        }
71
72        // Clean up any remaining array elements.
73        for (int index = newAtributesCount; index < attributesCount; index++)
74        {
75            attributes[index] = null;
76        }
77
78        // Update the number of attribuets.
79        programClass.u2attributesCount = newAtributesCount;
80    }
81
82
83    // Implementations for AttributeVisitor.
84
85    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
86
87
88    public void visitInnerClassesAttribute(Clazz clazz, InnerClassesAttribute innerClassesAttribute)
89    {
90        // Check whether the class itself is retargeted.
91        checkTarget(clazz);
92
93        // Check whether the referenced classes are retargeted.
94        innerClassesAttribute.innerClassEntriesAccept(clazz, this);
95    }
96
97
98    public void visitEnclosingMethodAttribute(Clazz clazz, EnclosingMethodAttribute enclosingMethodAttribute)
99    {
100        // Check whether the class itself is retargeted.
101        checkTarget(clazz);
102
103        // Check whether the referenced class is retargeted.
104        checkTarget(enclosingMethodAttribute.referencedClass);
105    }
106
107
108    // Implementations for InnerClassesInfoVisitor.
109
110    public void visitInnerClassesInfo(Clazz clazz, InnerClassesInfo innerClassesInfo)
111    {
112        // Check whether the inner class or the outer class are retargeted.
113        innerClassesInfo.innerClassConstantAccept(clazz, this);
114        innerClassesInfo.outerClassConstantAccept(clazz, this);
115    }
116
117
118    // Implementations for ConstantVisitor.
119
120    public void visitClassConstant(Clazz clazz, ClassConstant classConstant)
121    {
122        // Check whether the referenced class is retargeted.
123        checkTarget(classConstant.referencedClass);
124    }
125
126
127    // Small utility methods.
128
129    /**
130     * Sets the global return value to true if the given class is retargeted.
131     */
132    private void checkTarget(Clazz clazz)
133    {
134        if (clazz != null &&
135            ClassMerger.getTargetClass(clazz) != null)
136        {
137            retargeted = true;
138        }
139    }
140}