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 */ 21 package proguard.obfuscate; 22 23 import proguard.classfile.*; 24 import proguard.classfile.attribute.Attribute; 25 import proguard.classfile.attribute.visitor.AttributeVisitor; 26 import proguard.classfile.util.SimplifiedVisitor; 27 28 /** 29 * This ClassVisitor marks all attributes that it visits. 30 * 31 * @see AttributeShrinker 32 * 33 * @author Eric Lafortune 34 */ 35 public class AttributeUsageMarker 36 extends SimplifiedVisitor 37 implements AttributeVisitor 38 { 39 // A visitor info flag to indicate the attribute is being used. 40 private static final Object USED = new Object(); 41 42 43 // Implementations for AttributeVisitor. 44 visitAnyAttribute(Clazz clazz, Attribute attribute)45 public void visitAnyAttribute(Clazz clazz, Attribute attribute) 46 { 47 markAsUsed(attribute); 48 } 49 50 51 // Small utility methods. 52 53 /** 54 * Marks the given VisitorAccepter as being used (or useful). 55 * In this context, the VisitorAccepter will be an Attribute object. 56 */ markAsUsed(VisitorAccepter visitorAccepter)57 private static void markAsUsed(VisitorAccepter visitorAccepter) 58 { 59 visitorAccepter.setVisitorInfo(USED); 60 } 61 62 63 /** 64 * Returns whether the given VisitorAccepter has been marked as being used. 65 * In this context, the VisitorAccepter will be an Attribute object. 66 */ isUsed(VisitorAccepter visitorAccepter)67 static boolean isUsed(VisitorAccepter visitorAccepter) 68 { 69 return visitorAccepter.getVisitorInfo() == USED; 70 } 71 } 72