ConstantParameterFilter.java revision 8a6199f0c36a778f22394364347a301b0b28e94b
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.optimize; 22 23import proguard.classfile.*; 24import proguard.classfile.util.*; 25import proguard.classfile.visitor.MemberVisitor; 26import proguard.evaluation.value.Value; 27import proguard.optimize.evaluation.StoringInvocationUnit; 28import proguard.optimize.info.ParameterUsageMarker; 29 30/** 31 * This <code>MemberVisitor</code> delegates its visits to program methods 32 * to another given <code>MemberVisitor</code>, for each method parameter 33 * that has been marked as constant. 34 * 35 * @see StoringInvocationUnit 36 * @author Eric Lafortune 37 */ 38public class ConstantParameterFilter 39extends SimplifiedVisitor 40implements MemberVisitor 41{ 42 private final MemberVisitor constantParameterVisitor; 43 44 45 /** 46 * Creates a new ConstantParameterFilter. 47 * @param constantParameterVisitor the <code>MemberVisitor</code> to which 48 * visits will be delegated. 49 */ 50 public ConstantParameterFilter(MemberVisitor constantParameterVisitor) 51 { 52 this.constantParameterVisitor = constantParameterVisitor; 53 } 54 55 56 // Implementations for MemberVisitor. 57 58 public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) 59 { 60 // All parameters of non-static methods are shifted by one in the local 61 // variable frame. 62 int firstParameterIndex = 63 (programMethod.getAccessFlags() & ClassConstants.INTERNAL_ACC_STATIC) != 0 ? 64 0 : 1; 65 66 int parameterCount = 67 ClassUtil.internalMethodParameterCount(programMethod.getDescriptor(programClass)); 68 69 for (int index = firstParameterIndex; index < parameterCount; index++) 70 { 71 Value value = StoringInvocationUnit.getMethodParameterValue(programMethod, index); 72 if (value != null && 73 value.isParticular()) 74 { 75 constantParameterVisitor.visitProgramMethod(programClass, programMethod); 76 } 77 } 78 } 79}