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 */ 21 package proguard.optimize; 22 23 import proguard.classfile.*; 24 import proguard.classfile.util.MethodLinker; 25 import proguard.classfile.visitor.*; 26 import proguard.optimize.info.NoSideEffectMethodMarker; 27 28 29 /** 30 * This <code>ClassVisitor</code> and <code>MemberVisitor</code> 31 * marks classes and class members it visits. The marked elements 32 * will remain unchanged as necessary in the optimization step. 33 * 34 * @see NoSideEffectMethodMarker 35 * @author Eric Lafortune 36 */ 37 public class KeepMarker 38 implements ClassVisitor, 39 MemberVisitor 40 { 41 // A visitor info flag to indicate the visitor accepter is being kept. 42 private static final Object KEPT = new Object(); 43 44 45 // Implementations for ClassVisitor. 46 visitProgramClass(ProgramClass programClass)47 public void visitProgramClass(ProgramClass programClass) 48 { 49 markAsKept(programClass); 50 } 51 52 visitLibraryClass(LibraryClass libraryClass)53 public void visitLibraryClass(LibraryClass libraryClass) 54 { 55 markAsKept(libraryClass); 56 } 57 58 59 // Implementations for MemberVisitor. 60 visitProgramField(ProgramClass programClass, ProgramField programField)61 public void visitProgramField(ProgramClass programClass, ProgramField programField) 62 { 63 markAsKept(programField); 64 } 65 66 visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)67 public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) 68 { 69 markAsKept(MethodLinker.lastMember(programMethod)); 70 } 71 72 visitLibraryField(LibraryClass libraryClass, LibraryField libraryField)73 public void visitLibraryField(LibraryClass libraryClass, LibraryField libraryField) 74 { 75 markAsKept(libraryField); 76 } 77 78 visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod)79 public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod) 80 { 81 markAsKept(MethodLinker.lastMember(libraryMethod)); 82 } 83 84 85 // Small utility methods. 86 markAsKept(VisitorAccepter visitorAccepter)87 private static void markAsKept(VisitorAccepter visitorAccepter) 88 { 89 visitorAccepter.setVisitorInfo(KEPT); 90 } 91 92 isKept(VisitorAccepter visitorAccepter)93 public static boolean isKept(VisitorAccepter visitorAccepter) 94 { 95 // We're also checking for the constant in NoSideEffectMethodMarker, 96 // to keep things simple. 97 Object visitorInfo = 98 MethodLinker.lastVisitorAccepter(visitorAccepter).getVisitorInfo(); 99 100 return visitorInfo == KEPT || 101 visitorInfo == NoSideEffectMethodMarker.KEPT_BUT_NO_SIDE_EFFECTS; 102 } 103 } 104