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.classfile.util;
22
23import proguard.classfile.*;
24import proguard.classfile.attribute.Attribute;
25import proguard.classfile.attribute.visitor.AttributeVisitor;
26import proguard.classfile.constant.*;
27import proguard.classfile.constant.visitor.ConstantVisitor;
28import proguard.classfile.visitor.ClassVisitor;
29
30/**
31 * This ClassVisitor shares strings in the class files that it visits.
32 *
33 * @author Eric Lafortune
34 */
35public class StringSharer
36extends      SimplifiedVisitor
37implements   ClassVisitor,
38             ConstantVisitor,
39             AttributeVisitor
40{
41    // A fields acting as an argument for the visitor methods.
42    private String name;
43    private String type;
44
45
46    // Implementations for ClassVisitor.
47
48    public void visitProgramClass(ProgramClass programClass)
49    {
50        // Replace name strings in the constant pool by shared strings.
51        programClass.constantPoolEntriesAccept(this);
52
53        // Replace attribute name strings in the constant pool by internalized
54        // strings.
55        programClass.attributesAccept(this);
56    }
57
58
59    public void visitLibraryClass(LibraryClass libraryClass)
60    {
61        // Replace the super class name string by the shared name string.
62        Clazz superClass = libraryClass.superClass;
63        if (superClass != null)
64        {
65            libraryClass.superClassName = superClass.getName();
66        }
67
68        // Replace the interface name strings by the shared name strings.
69        if (libraryClass.interfaceNames != null)
70        {
71            String[] interfaceNames   = libraryClass.interfaceNames;
72            Clazz[]  interfaceClasses = new Clazz[interfaceNames.length];
73
74            for (int index = 0; index < interfaceNames.length; index++)
75            {
76                // Keep a reference to the interface class.
77                Clazz interfaceClass = interfaceClasses[index];
78                if (interfaceClass != null)
79                {
80                    interfaceNames[index] = interfaceClass.getName();
81                }
82            }
83        }
84    }
85
86
87    // Implementations for ConstantVisitor.
88
89
90    public void visitAnyConstant(Clazz clazz, Constant constant) {}
91
92
93    public void visitStringConstant(Clazz clazz, StringConstant stringConstant)
94    {
95        Member referencedMember = stringConstant.referencedMember;
96        if (referencedMember != null)
97        {
98            Clazz referencedClass = stringConstant.referencedClass;
99
100            // Put the actual class member's name in the class pool.
101            name = referencedMember.getName(referencedClass);
102            clazz.constantPoolEntryAccept(stringConstant.u2stringIndex, this);
103        }
104    }
105
106
107    public void visitAnyRefConstant(Clazz clazz, RefConstant refConstant)
108    {
109        Member referencedMember = refConstant.referencedMember;
110        if (referencedMember != null)
111        {
112            Clazz referencedClass = refConstant.referencedClass;
113
114            // Put the actual class member's name and type strings in the class
115            // pool.
116            name = referencedMember.getName(referencedClass);
117            type = referencedMember.getDescriptor(referencedClass);
118            clazz.constantPoolEntryAccept(refConstant.u2nameAndTypeIndex, this);
119        }
120    }
121
122
123    public void visitNameAndTypeConstant(Clazz clazz, NameAndTypeConstant nameAndTypeConstant)
124    {
125        if (name != null)
126        {
127            // Put the actual class member's name and type strings in the class
128            // pool.
129            clazz.constantPoolEntryAccept(nameAndTypeConstant.u2nameIndex, this);
130            name = type;
131            clazz.constantPoolEntryAccept(nameAndTypeConstant.u2descriptorIndex, this);
132        }
133    }
134
135
136    public void visitClassConstant(Clazz clazz, ClassConstant classConstant)
137    {
138        Clazz referencedClass = classConstant.referencedClass;
139        if (referencedClass != null)
140        {
141            // Put the actual class's name string in the class pool.
142            name = referencedClass.getName();
143            clazz.constantPoolEntryAccept(classConstant.u2nameIndex, this);
144        }
145    }
146
147
148    public void visitUtf8Constant(Clazz clazz, Utf8Constant utf8Constant)
149    {
150        // Do we have a new string to put into this constant?
151        if (name != null)
152        {
153            // Replace the string, if it's actually the same.
154            if (name.equals(utf8Constant.getString()))
155            {
156                utf8Constant.setString(name);
157            }
158
159            name = null;
160        }
161    }
162
163
164    // Implementations for AttributeVisitor.
165
166    public void visitAnyAttribute(Clazz clazz, Attribute attribute)
167    {
168        // Put the internalized attribute's name string in the class pool.
169        name = attribute.getAttributeName(clazz).intern();
170        clazz.constantPoolEntryAccept(attribute.u2attributeNameIndex, this);
171    }
172}
173