1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2013 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
31import java.util.Arrays;
32
33/**
34 * This ClassVisitor removes InnerClasses and EnclosingMethod attributes in
35 * classes that are retargeted or that refer to classes that are retargeted.
36 *
37 * @see ClassMerger
38 * @author Eric Lafortune
39 */
40public class RetargetedInnerClassAttributeRemover
41extends      SimplifiedVisitor
42implements   ClassVisitor,
43             AttributeVisitor,
44             InnerClassesInfoVisitor,
45             ConstantVisitor
46{
47    private boolean retargeted;
48
49
50    // Implementations for ClassVisitor.
51
52    public void visitProgramClass(ProgramClass programClass)
53    {
54        int         attributesCount = programClass.u2attributesCount;
55        Attribute[] attributes      = programClass.attributes;
56
57        int newAtributesCount = 0;
58
59        // Copy over all non-retargeted attributes.
60        for (int index = 0; index < attributesCount; index++)
61        {
62            Attribute attribute = attributes[index];
63
64            // Check if it's an InnerClasses or EnclosingMethod attribute in
65            // a retargeted class or referring to a retargeted class.
66            retargeted = false;
67            attribute.accept(programClass, this);
68            if (!retargeted)
69            {
70                attributes[newAtributesCount++] = attribute;
71            }
72        }
73
74        // Clean up any remaining array elements.
75        Arrays.fill(attributes, newAtributesCount, attributesCount, null);
76
77        // Update the number of attributes.
78        programClass.u2attributesCount = newAtributesCount;
79    }
80
81
82    // Implementations for AttributeVisitor.
83
84    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
85
86
87    public void visitInnerClassesAttribute(Clazz clazz, InnerClassesAttribute innerClassesAttribute)
88    {
89        // Check whether the class itself is retargeted.
90        checkTarget(clazz);
91
92        if (!retargeted)
93        {
94            // Check whether the referenced classes are retargeted.
95            innerClassesAttribute.innerClassEntriesAccept(clazz, this);
96            int                classesCount = innerClassesAttribute.u2classesCount;
97            InnerClassesInfo[] classes      = innerClassesAttribute.classes;
98
99            int newClassesCount = 0;
100
101            // Copy over all non-retargeted attributes.
102            for (int index = 0; index < classesCount; index++)
103            {
104                InnerClassesInfo classInfo = classes[index];
105
106                // Check if the outer class or inner class is a retargeted class.
107                retargeted = false;
108                classInfo.outerClassConstantAccept(clazz, this);
109                classInfo.innerClassConstantAccept(clazz, this);
110                if (!retargeted)
111                {
112                    classes[newClassesCount++] = classInfo;
113                }
114            }
115
116            // Clean up any remaining array elements.
117            Arrays.fill(classes, newClassesCount, classesCount, null);
118
119            // Update the number of classes.
120            innerClassesAttribute.u2classesCount = newClassesCount;
121
122            // Remove the attribute altogether if it's empty.
123            retargeted = newClassesCount == 0;
124        }
125    }
126
127
128    public void visitEnclosingMethodAttribute(Clazz clazz, EnclosingMethodAttribute enclosingMethodAttribute)
129    {
130        // Check whether the class itself is retargeted.
131        checkTarget(clazz);
132
133        // Check whether the referenced class is retargeted.
134        checkTarget(enclosingMethodAttribute.referencedClass);
135    }
136
137
138    // Implementations for InnerClassesInfoVisitor.
139
140    public void visitInnerClassesInfo(Clazz clazz, InnerClassesInfo innerClassesInfo)
141    {
142        // Check whether the inner class or the outer class are retargeted.
143        innerClassesInfo.innerClassConstantAccept(clazz, this);
144        innerClassesInfo.outerClassConstantAccept(clazz, this);
145    }
146
147
148    // Implementations for ConstantVisitor.
149
150    public void visitClassConstant(Clazz clazz, ClassConstant classConstant)
151    {
152        // Check whether the referenced class is retargeted.
153        checkTarget(classConstant.referencedClass);
154    }
155
156
157    // Small utility methods.
158
159    /**
160     * Sets the global return value to true if the given class is retargeted.
161     */
162    private void checkTarget(Clazz clazz)
163    {
164        if (clazz != null &&
165            ClassMerger.getTargetClass(clazz) != null)
166        {
167            retargeted = true;
168        }
169    }
170}