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/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2013 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.attribute.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.util.SimplifiedVisitor;
import proguard.classfile.visitor.*;
import java.util.Arrays;
/**
* This ClassVisitor removes attributes that are not marked as being used or
* required.
*
* @see AttributeUsageMarker
*
* @author Eric Lafortune
*/
public class AttributeShrinker
extends SimplifiedVisitor
implements ClassVisitor,
MemberVisitor,
AttributeVisitor
{
// Implementations for ClassVisitor.
public void visitProgramClass(ProgramClass programClass)
{
// Compact the array for class attributes.
programClass.u2attributesCount =
shrinkArray(programClass.attributes,
programClass.u2attributesCount);
// Compact the attributes in fields, methods, and class attributes,
programClass.fieldsAccept(this);
programClass.methodsAccept(this);
programClass.attributesAccept(this);
}
public void visitLibraryClass(LibraryClass libraryClass)
{
// Library classes are left unchanged.
}
// Implementations for MemberVisitor.
public void visitProgramMember(ProgramClass programClass, ProgramMember programMember)
{
// Compact the attributes array.
programMember.u2attributesCount =
shrinkArray(programMember.attributes,
programMember.u2attributesCount);
// Compact any attributes of the remaining attributes.
programMember.attributesAccept(programClass, this);
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
// Compact the attributes array.
codeAttribute.u2attributesCount =
shrinkArray(codeAttribute.attributes,
codeAttribute.u2attributesCount);
}
// Small utility methods.
/**
* Removes all VisitorAccepter objects that are not marked as being used
* from the given array.
* @return the new number of VisitorAccepter objects.
*/
private static int shrinkArray(VisitorAccepter[] array, int length)
{
int counter = 0;
// Shift the used objects together.
for (int index = 0; index < length; index++)
{
if (AttributeUsageMarker.isUsed(array[index]))
{
array[counter++] = array[index];
}
}
// Clear the remaining array elements.
Arrays.fill(array, counter, length, null);
return counter;
}
}
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