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 */ 21 22package proguard.shrink; 23 24import proguard.classfile.*; 25import proguard.classfile.attribute.*; 26import proguard.classfile.attribute.visitor.*; 27import proguard.classfile.constant.Constant; 28import proguard.classfile.constant.visitor.ConstantVisitor; 29import proguard.classfile.util.SimplifiedVisitor; 30import proguard.classfile.visitor.ClassVisitor; 31 32/** 33 * This AttributeVisitor recursively marks all information that points to used 34 * classes, in the LocalVariableTable and LocalVariableTypeTable attributes that 35 * it visits. 36 * 37 * @see UsageMarker 38 * 39 * @author Eric Lafortune 40 */ 41public class LocalVariableTypeUsageMarker 42extends SimplifiedVisitor 43implements AttributeVisitor, 44 LocalVariableInfoVisitor, 45 LocalVariableTypeInfoVisitor, 46 ClassVisitor, 47 ConstantVisitor 48{ 49 private final UsageMarker usageMarker; 50 51 // Fields acting as a return parameters for several methods. 52 private boolean tableUsed; 53 private boolean variableInfoUsed; 54 55 56 /** 57 * Creates a new LocalVariableTypeUsageMarker. 58 * @param usageMarker the usage marker that is used to mark the classes 59 * and class members. 60 */ 61 public LocalVariableTypeUsageMarker(UsageMarker usageMarker) 62 { 63 this.usageMarker = usageMarker; 64 } 65 66 67 // Implementations for AttributeVisitor. 68 69 public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} 70 71 72 public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute) 73 { 74 // Check and mark the individual entries. 75 tableUsed = false; 76 localVariableTableAttribute.localVariablesAccept(clazz, method, codeAttribute, this); 77 78 // Mark the table if any of the entries is marked. 79 if (tableUsed) 80 { 81 usageMarker.markAsUsed(localVariableTableAttribute); 82 83 markConstant(clazz, localVariableTableAttribute.u2attributeNameIndex); 84 } 85 } 86 87 88 public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute) 89 { 90 // Check and mark the individual entries. 91 tableUsed = false; 92 localVariableTypeTableAttribute.localVariablesAccept(clazz, method, codeAttribute, this); 93 94 // Mark the table if any of the entries is marked. 95 if (tableUsed) 96 { 97 usageMarker.markAsUsed(localVariableTypeTableAttribute); 98 99 markConstant(clazz, localVariableTypeTableAttribute.u2attributeNameIndex); 100 } 101 } 102 103 104 // Implementations for LocalVariableInfoVisitor. 105 106 public void visitLocalVariableInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableInfo localVariableInfo) 107 { 108 // Only keep the local variable info if all of its classes are used. 109 variableInfoUsed = true; 110 localVariableInfo.referencedClassAccept(this); 111 112 if (variableInfoUsed) 113 { 114 // We got a positive used flag, so the local variable info is useful. 115 usageMarker.markAsUsed(localVariableInfo); 116 117 markConstant(clazz, localVariableInfo.u2nameIndex); 118 markConstant(clazz, localVariableInfo.u2descriptorIndex); 119 120 tableUsed = true; 121 } 122 } 123 124 125 // Implementations for LocalVariableTypeInfoVisitor. 126 127 public void visitLocalVariableTypeInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeInfo localVariableTypeInfo) 128 { 129 // Only keep the local variable info if all of its classes are used. 130 variableInfoUsed = true; 131 localVariableTypeInfo.referencedClassesAccept(this); 132 133 if (variableInfoUsed) 134 { 135 // We got a positive used flag, so the local variable info is useful. 136 usageMarker.markAsUsed(localVariableTypeInfo); 137 138 markConstant(clazz, localVariableTypeInfo.u2nameIndex); 139 markConstant(clazz, localVariableTypeInfo.u2signatureIndex); 140 141 tableUsed = true; 142 } 143 } 144 145 146 // Implementations for ClassVisitor. 147 148 public void visitLibraryClass(LibraryClass libraryClass) {} 149 150 151 public void visitProgramClass(ProgramClass programClass) 152 { 153 // Don't keep the local variable info if one of its classes is not used. 154 if (!usageMarker.isUsed(programClass)) 155 { 156 variableInfoUsed = false; 157 } 158 } 159 160 161 // Implementations for ConstantVisitor. 162 163 public void visitAnyConstant(Clazz clazz, Constant constant) 164 { 165 usageMarker.markAsUsed(constant); 166 } 167 168 169 // Small utility methods. 170 171 /** 172 * Marks the given constant pool entry of the given class. 173 */ 174 private void markConstant(Clazz clazz, int index) 175 { 176 clazz.constantPoolEntryAccept(index, this); 177 } 178} 179