| /* |
| * ProGuard -- shrinking, optimization, obfuscation, and preverification |
| * of Java bytecode. |
| * |
| * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu) |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License as published by the Free |
| * Software Foundation; either version 2 of the License, or (at your option) |
| * any later version. |
| * |
| * This program is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| * more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| package proguard.classfile.editor; |
| |
| import proguard.classfile.*; |
| import proguard.classfile.attribute.*; |
| import proguard.classfile.attribute.visitor.AttributeVisitor; |
| import proguard.classfile.util.SimplifiedVisitor; |
| |
| /** |
| * This AttributeVisitor accumulates specified changes to local variables, and |
| * then applies these accumulated changes to the code attributes that it visits. |
| * |
| * @author Eric Lafortune |
| */ |
| public class VariableEditor |
| extends SimplifiedVisitor |
| implements AttributeVisitor |
| { |
| private boolean modified; |
| |
| private boolean[] deleted = new boolean[ClassConstants.TYPICAL_VARIABLES_SIZE]; |
| private int[] variableMap = new int[ClassConstants.TYPICAL_VARIABLES_SIZE]; |
| |
| private final VariableRemapper variableRemapper = new VariableRemapper(); |
| |
| |
| /** |
| * Resets the accumulated code changes. |
| * @param maxLocals the length of the local variable frame that will be |
| * edited next. |
| */ |
| public void reset(int maxLocals) |
| { |
| // Try to reuse the previous array. |
| if (deleted.length < maxLocals) |
| { |
| deleted = new boolean[maxLocals]; |
| } |
| else |
| { |
| for (int index = 0; index < maxLocals; index++) |
| { |
| deleted[index] = false; |
| } |
| } |
| |
| modified = false; |
| } |
| |
| |
| /** |
| * Remembers to delete the given variable. |
| * @param variableIndex the index of the variable to be deleted. |
| */ |
| public void deleteVariable(int variableIndex) |
| { |
| deleted[variableIndex] = true; |
| |
| modified = true; |
| } |
| |
| |
| /** |
| * Returns whether the given variable at the given offset has deleted. |
| */ |
| public boolean isDeleted(int instructionOffset) |
| { |
| return deleted[instructionOffset]; |
| } |
| |
| |
| // Implementations for AttributeVisitor. |
| |
| public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} |
| |
| |
| public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) |
| { |
| // Avoid doing any work if nothing is changing anyway. |
| if (!modified) |
| { |
| return; |
| } |
| |
| int oldMaxLocals = codeAttribute.u2maxLocals; |
| |
| // Make sure there is a sufficiently large variable map. |
| if (variableMap.length < oldMaxLocals) |
| { |
| variableMap = new int[oldMaxLocals]; |
| } |
| |
| // Fill out the variable map. |
| int newVariableIndex = 0; |
| for (int oldVariableIndex = 0; oldVariableIndex < oldMaxLocals; oldVariableIndex++) |
| { |
| variableMap[oldVariableIndex] = deleted[oldVariableIndex] ? |
| -1 : newVariableIndex++; |
| } |
| |
| // Set the map. |
| variableRemapper.setVariableMap(variableMap); |
| |
| // Remap the variables. |
| variableRemapper.visitCodeAttribute(clazz, method, codeAttribute); |
| |
| // Update the length of local variable frame. |
| codeAttribute.u2maxLocals = newVariableIndex; |
| } |
| } |