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