| /* |
| * 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.obfuscate; |
| |
| import proguard.classfile.*; |
| import proguard.classfile.constant.Constant; |
| import proguard.classfile.editor.ConstantPoolRemapper; |
| import proguard.classfile.visitor.ClassVisitor; |
| |
| |
| /** |
| * This ClassVisitor removes UTF-8 constant pool entries that are not marked |
| * as being used. |
| * |
| * @see Utf8UsageMarker |
| * |
| * @author Eric Lafortune |
| */ |
| public class Utf8Shrinker implements ClassVisitor |
| { |
| private int[] constantIndexMap = new int[ClassConstants.TYPICAL_CONSTANT_POOL_SIZE]; |
| private final ConstantPoolRemapper constantPoolRemapper = new ConstantPoolRemapper(); |
| |
| |
| // Implementations for ClassVisitor. |
| |
| public void visitProgramClass(ProgramClass programClass) |
| { |
| // Shift the used constant pool entries together, filling out the |
| // index map. |
| programClass.u2constantPoolCount = |
| shrinkConstantPool(programClass.constantPool, |
| programClass.u2constantPoolCount); |
| |
| // Remap all constant pool references. |
| constantPoolRemapper.setConstantIndexMap(constantIndexMap); |
| constantPoolRemapper.visitProgramClass(programClass); |
| } |
| |
| |
| public void visitLibraryClass(LibraryClass libraryClass) |
| { |
| } |
| |
| |
| // Small utility methods. |
| |
| /** |
| * Removes all UTF-8 entries that are not marked as being used |
| * from the given constant pool. |
| * @return the new number of entries. |
| */ |
| private int shrinkConstantPool(Constant[] constantPool, int length) |
| { |
| // Create a new index map, if necessary. |
| if (constantIndexMap.length < length) |
| { |
| constantIndexMap = new int[length]; |
| } |
| |
| int counter = 1; |
| boolean isUsed = false; |
| |
| // Shift the used constant pool entries together. |
| for (int index = 1; index < length; index++) |
| { |
| constantIndexMap[index] = counter; |
| |
| Constant constant = constantPool[index]; |
| |
| // Don't update the flag if this is the second half of a long entry. |
| if (constant != null) |
| { |
| isUsed = constant.getTag() != ClassConstants.CONSTANT_Utf8 || |
| Utf8UsageMarker.isUsed(constant); |
| } |
| |
| if (isUsed) |
| { |
| constantPool[counter++] = constant; |
| } |
| } |
| |
| // Clear the remaining constant pool elements. |
| for (int index = counter; index < length; index++) |
| { |
| constantPool[index] = null; |
| } |
| |
| return counter; |
| } |
| } |