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ProGuard is a free Java class file shrinker, optimizer, and obfuscator. It removes unused classes, fields, methods, and attributes. It then optimizes the bytecode. It then renames the remaining classes, fields, and methods using short meaningless names. Finally, it preverifies the processed code for Java 6 or for Java Micro Edition.
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/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2009 Eric Lafortune ([email protected])
*
* 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.shrink;
import proguard.classfile.*;
import proguard.classfile.visitor.*;
/**
* This ClassVisitor and MemberVisitor recursively marks all classes
* and class elements that are being used. For each element, it finds the
* shortest chain of dependencies.
*
* @see ClassShrinker
*
* @author Eric Lafortune
*/
public class ShortestUsageMarker extends UsageMarker
{
private static final ShortestUsageMark INITIAL_MARK =
new ShortestUsageMark("is kept by a directive in the configuration.\n\n");
// A field acting as a parameter to the visitor methods.
private ShortestUsageMark currentUsageMark = INITIAL_MARK;
// A utility object to check for recursive causes.
private final MyRecursiveCauseChecker recursiveCauseChecker = new MyRecursiveCauseChecker();
// Overriding implementations for UsageMarker.
protected void markProgramClassBody(ProgramClass programClass)
{
ShortestUsageMark previousUsageMark = currentUsageMark;
currentUsageMark = new ShortestUsageMark(getShortestUsageMark(programClass),
"is extended by ",
10000,
programClass);
super.markProgramClassBody(programClass);
currentUsageMark = previousUsageMark;
}
protected void markProgramFieldBody(ProgramClass programClass, ProgramField programField)
{
ShortestUsageMark previousUsageMark = currentUsageMark;
currentUsageMark = new ShortestUsageMark(getShortestUsageMark(programField),
"is referenced by ",
1,
programClass,
programField);
super.markProgramFieldBody(programClass, programField);
currentUsageMark = previousUsageMark;
}
protected void markProgramMethodBody(ProgramClass programClass, ProgramMethod programMethod)
{
ShortestUsageMark previousUsageMark = currentUsageMark;
currentUsageMark = new ShortestUsageMark(getShortestUsageMark(programMethod),
"is invoked by ",
1,
programClass,
programMethod);
super.markProgramMethodBody(programClass, programMethod);
currentUsageMark = previousUsageMark;
}
protected void markMethodHierarchy(Clazz clazz, Method method)
{
ShortestUsageMark previousUsageMark = currentUsageMark;
currentUsageMark = new ShortestUsageMark(getShortestUsageMark(method),
"implements ",
100,
clazz,
method);
super.markMethodHierarchy(clazz, method);
currentUsageMark = previousUsageMark;
}
// Small utility methods.
protected void markAsUsed(VisitorAccepter visitorAccepter)
{
Object visitorInfo = visitorAccepter.getVisitorInfo();
ShortestUsageMark shortestUsageMark =
visitorInfo != null &&
visitorInfo instanceof ShortestUsageMark &&
!((ShortestUsageMark)visitorInfo).isCertain() &&
!currentUsageMark.isShorter((ShortestUsageMark)visitorInfo) ?
new ShortestUsageMark((ShortestUsageMark)visitorInfo, true):
currentUsageMark;
visitorAccepter.setVisitorInfo(shortestUsageMark);
}
protected boolean shouldBeMarkedAsUsed(VisitorAccepter visitorAccepter)
{
Object visitorInfo = visitorAccepter.getVisitorInfo();
return //!(visitorAccepter instanceof Clazz &&
// isCausedBy(currentUsageMark, (Clazz)visitorAccepter)) &&
(visitorInfo == null ||
!(visitorInfo instanceof ShortestUsageMark) ||
!((ShortestUsageMark)visitorInfo).isCertain() ||
currentUsageMark.isShorter((ShortestUsageMark)visitorInfo));
}
protected boolean isUsed(VisitorAccepter visitorAccepter)
{
Object visitorInfo = visitorAccepter.getVisitorInfo();
return visitorInfo != null &&
visitorInfo instanceof ShortestUsageMark &&
((ShortestUsageMark)visitorInfo).isCertain();
}
protected void markAsPossiblyUsed(VisitorAccepter visitorAccepter)
{
visitorAccepter.setVisitorInfo(new ShortestUsageMark(currentUsageMark, false));
}
protected boolean shouldBeMarkedAsPossiblyUsed(VisitorAccepter visitorAccepter)
{
Object visitorInfo = visitorAccepter.getVisitorInfo();
return visitorInfo == null ||
!(visitorInfo instanceof ShortestUsageMark) ||
(!((ShortestUsageMark)visitorInfo).isCertain() &&
currentUsageMark.isShorter((ShortestUsageMark)visitorInfo));
}
protected boolean isPossiblyUsed(VisitorAccepter visitorAccepter)
{
Object visitorInfo = visitorAccepter.getVisitorInfo();
return visitorInfo != null &&
visitorInfo instanceof ShortestUsageMark &&
!((ShortestUsageMark)visitorInfo).isCertain();
}
protected ShortestUsageMark getShortestUsageMark(VisitorAccepter visitorAccepter)
{
Object visitorInfo = visitorAccepter.getVisitorInfo();
return (ShortestUsageMark)visitorInfo;
}
// Small utility methods.
private boolean isCausedBy(ShortestUsageMark shortestUsageMark,
Clazz clazz)
{
return recursiveCauseChecker.check(shortestUsageMark, clazz);
}
private class MyRecursiveCauseChecker implements ClassVisitor, MemberVisitor
{
private Clazz checkClass;
private boolean isRecursing;
public boolean check(ShortestUsageMark shortestUsageMark,
Clazz clazz)
{
checkClass = clazz;
isRecursing = false;
shortestUsageMark.acceptClassVisitor(this);
shortestUsageMark.acceptMemberVisitor(this);
return isRecursing;
}
// Implementations for ClassVisitor.
public void visitProgramClass(ProgramClass programClass)
{
checkCause(programClass);
}
public void visitLibraryClass(LibraryClass libraryClass)
{
checkCause(libraryClass);
}
// Implementations for MemberVisitor.
public void visitProgramField(ProgramClass programClass, ProgramField programField)
{
checkCause(programField);
}
public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
{
checkCause(programMethod);
}
public void visitLibraryField(LibraryClass libraryClass, LibraryField libraryField)
{
checkCause(libraryField);
}
public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod)
{
checkCause(libraryMethod);
}
// Small utility methods.
private void checkCause(VisitorAccepter visitorAccepter)
{
if (ShortestUsageMarker.this.isUsed(visitorAccepter))
{
ShortestUsageMark shortestUsageMark = ShortestUsageMarker.this.getShortestUsageMark(visitorAccepter);
// Check the class of this mark, if any
isRecursing = shortestUsageMark.isCausedBy(checkClass);
// Check the causing class or method, if still necessary.
if (!isRecursing)
{
shortestUsageMark.acceptClassVisitor(this);
shortestUsageMark.acceptMemberVisitor(this);
}
}
}
}
}