usagemarker.java

ProGuard 是一个免费的 Java类文件的压缩

/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2007 Eric Lafortune ([e-mail])
 *
 * 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.attribute.*;
import proguard.classfile.attribute.annotation.*;
import proguard.classfile.attribute.annotation.visitor.*;
import proguard.classfile.attribute.preverification.*;
import proguard.classfile.attribute.preverification.visitor.*;
import proguard.classfile.attribute.visitor.*;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.SimplifiedVisitor;
import proguard.classfile.visitor.*;


/**
 * This ClassVisitor and MemberVisitor recursively marks all
 * classes and class elements that are being used.
 *
 * @see ClassShrinker
 *
 * @author Eric Lafortune
 */
class      UsageMarker
extends    SimplifiedVisitor
implements ClassVisitor,
           MemberVisitor,
           ConstantVisitor,
           AttributeVisitor,
           InnerClassesInfoVisitor,
           ExceptionInfoVisitor,
           StackMapFrameVisitor,
           VerificationTypeVisitor,
           LocalVariableInfoVisitor,
           LocalVariableTypeInfoVisitor,
           AnnotationVisitor,
           ElementValueVisitor,
           InstructionVisitor
{
    // A visitor info flag to indicate the ProgramMember object is being used,
    // if its Clazz can be determined as being used as well.
    private static final Object POSSIBLY_USED = new Object();
    // A visitor info flag to indicate the visitor accepter is being used.
    private static final Object USED          = new Object();


    private MyInterfaceUsageMarker          interfaceUsageMarker          = new MyInterfaceUsageMarker();
    private MyPossiblyUsedMethodUsageMarker possiblyUsedMethodUsageMarker = new MyPossiblyUsedMethodUsageMarker();
//    private ClassVisitor       dynamicClassMarker   =
//        new MultiClassVisitor(
//        new ClassVisitor[]
//        {
//            this,
//            new NamedMethodVisitor(ClassConstants.INTERNAL_METHOD_NAME_INIT,
//                                   ClassConstants.INTERNAL_METHOD_TYPE_INIT,
//                                   this)
//        });


    // Implementations for ClassVisitor.

    public void visitProgramClass(ProgramClass programClass)
    {
        if (shouldBeMarkedAsUsed(programClass))
        {
            // Mark this class.
            markAsUsed(programClass);

            markProgramClassBody(programClass);
        }
    }


    protected void markProgramClassBody(ProgramClass programClass)
    {
        // Mark this class's name.
        markConstant(programClass, programClass.u2thisClass);

        // Mark the superclass.
        if (programClass.u2superClass != 0)
        {
            markConstant(programClass, programClass.u2superClass);
        }

        // Give the interfaces preliminary marks.
        programClass.hierarchyAccept(false, false, true, false,
                                     interfaceUsageMarker);

        // Explicitly mark the <clinit> method.
        programClass.methodAccept(ClassConstants.INTERNAL_METHOD_NAME_CLINIT,
                                  ClassConstants.INTERNAL_METHOD_TYPE_CLINIT,
                                  this);

        // Explicitly mark the parameterless <init> method.
        programClass.methodAccept(ClassConstants.INTERNAL_METHOD_NAME_INIT,
                                  ClassConstants.INTERNAL_METHOD_TYPE_INIT,
                                  this);

        // Process all methods that have already been marked as possibly used.
        programClass.methodsAccept(possiblyUsedMethodUsageMarker);

        // Mark the attributes.
        programClass.attributesAccept(this);
    }


    public void visitLibraryClass(LibraryClass libraryClass)
    {
        if (shouldBeMarkedAsUsed(libraryClass))
        {
            markAsUsed(libraryClass);

            // We're not going to analyze all library code. We're assuming that
            // if this class is being used, all of its methods will be used as
            // well. We'll mark them as such (here and in all subclasses).

            // Mark the superclass.
            Clazz superClass = libraryClass.superClass;
            if (superClass != null)
            {
                superClass.accept(this);
            }

            // Mark the interfaces.
            Clazz[] interfaceClasses = libraryClass.interfaceClasses;
            if (interfaceClasses != null)
            {
                for (int index = 0; index < interfaceClasses.length; index++)
                {
                    if (interfaceClasses[index] != null)
                    {
                        interfaceClasses[index].accept(this);
                    }
                }
            }

            // Mark all methods.
            libraryClass.methodsAccept(this);
        }
    }


    /**
     * This ClassVisitor marks ProgramClass objects as possibly used,
     * and it visits LibraryClass objects with its outer UsageMarker.
     */
    private class MyInterfaceUsageMarker
    implements    ClassVisitor
    {
        public void visitProgramClass(ProgramClass programClass)
        {
            if (shouldBeMarkedAsPossiblyUsed(programClass))
            {
                // We can't process the interface yet, because it might not
                // be required. Give it a preliminary mark.
                markAsPossiblyUsed(programClass);
            }
        }

        public void visitLibraryClass(LibraryClass libraryClass)
        {
            // Make sure all library interface methods are marked.
            UsageMarker.this.visitLibraryClass(libraryClass);
        }
    }


    private class MyPossiblyUsedMethodUsageMarker
    extends       SimplifiedVisitor
    implements    MemberVisitor
    {
        // Implementations for MemberVisitor.

        public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
        {
            // Has the method already been referenced?
            if (isPossiblyUsed(programMethod))
            {
                markAsUsed(programMethod);

                // Mark the method body.
                markProgramMethodBody(programClass, programMethod);

                // Note that, if the method has been marked as possibly used,
                // the method hierarchy has already been marked (cfr. below).
            }
        }


    }


    // Implementations for MemberVisitor.

    public void visitProgramField(ProgramClass programClass, ProgramField programField)
    {
        if (shouldBeMarkedAsUsed(programField))
        {
            markAsUsed(programField);

            // Mark the name and descriptor.
            markConstant(programClass, programField.u2nameIndex);
            markConstant(programClass, programField.u2descriptorIndex);

            // Mark the attributes.
            programField.attributesAccept(programClass, this);

            // Mark the classes referenced in the descriptor string.
            programField.referencedClassesAccept(this);
        }
    }


    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
    {
        if (shouldBeMarkedAsUsed(programMethod))
        {
            // Is the method's class used?
            if (isUsed(programClass))
            {
                markAsUsed(programMethod);

                // Mark the method body.
                markProgramMethodBody(programClass, programMethod);

                // Mark the method hierarchy.
                markMethodHierarchy(programClass, programMethod);
            }

            // Hasn't the method been marked as possibly being used yet?
            else if (shouldBeMarkedAsPossiblyUsed(programMethod))
            {
                // We can't process the method yet, because the class isn't
                // marked as being used (yet). Give it a preliminary mark.
                markAsPossiblyUsed(programMethod);

                // Mark the method hierarchy.
                markMethodHierarchy(programClass, programMethod);
            }
        }
    }


    public void visitLibraryField(LibraryClass programClass, LibraryField programField) {}


    public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod)
    {
        if (shouldBeMarkedAsUsed(libraryMethod))
        {
            markAsUsed(libraryMethod);

            // Mark the method hierarchy.
            markMethodHierarchy(libraryClass, libraryMethod);
        }
    }


    protected void markProgramMethodBody(ProgramClass programClass, ProgramMethod programMethod)
    {
        // Mark the name and descriptor.
        markConstant(programClass, programMethod.u2nameIndex);
        markConstant(programClass, programMethod.u2descriptorIndex);

        // Mark the attributes.
        programMethod.attributesAccept(programClass, this);

        // Mark the classes referenced in the descriptor string.
        programMethod.referencedClassesAccept(this);
    }


    /**
     * Marks the hierarchy of implementing or overriding methods corresponding
     * to the given method, if any.
     */
    protected void markMethodHierarchy(Clazz clazz, Method method)
    {
        clazz.methodImplementationsAccept(method, false, this);
    }


    // Implementations for ConstantVisitor.

    public void visitIntegerConstant(Clazz clazz, IntegerConstant integerConstant)
    {
        if (shouldBeMarkedAsUsed(integerConstant))
        {
            markAsUsed(integerConstant);
        }
    }


    public void visitLongConstant(Clazz clazz, LongConstant longConstant)
    {
        if (shouldBeMarkedAsUsed(longConstant))
        {
            markAsUsed(longConstant);
        }
    }


    public void visitFloatConstant(Clazz clazz, FloatConstant floatConstant)
    {
        if (shouldBeMarkedAsUsed(floatConstant))
        {
            markAsUsed(floatConstant);
        }
    }


    public void visitDoubleConstant(Clazz clazz, DoubleConstant doubleConstant)
    {
        if (shouldBeMarkedAsUsed(doubleConstant))
        {
            markAsUsed(doubleConstant);
        }
    }


    public void visitStringConstant(Clazz clazz, StringConstant stringConstant)
    {
        if (shouldBeMarkedAsUsed(stringConstant))
        {
            markAsUsed(stringConstant);

            markConstant(clazz, stringConstant.u2stringIndex);

            // Mark the referenced class and its parameterless constructor,
            // if the string is being used in a Class.forName construct.
            //stringConstant.referencedClassAccept(dynamicClassMarker);

            // Mark the referenced class.
            stringConstant.referencedClassAccept(this);
        }
    }


    public void visitUtf8Constant(Clazz clazz, Utf8Constant utf8Constant)
    {
        if (shouldBeMarkedAsUsed(utf8Constant))
        {
            markAsUsed(utf8Constant);
        }
    }


    public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant)
    {
        visitRefConstant(clazz, fieldrefConstant);
    }


    public void visitInterfaceMethodrefConstant(Clazz clazz, InterfaceMethodrefConstant interfaceMethodrefConstant)
    {
        visitRefConstant(clazz, interfaceMethodrefConstant);
    }


    public void visitMethodrefConstant(Clazz clazz, MethodrefConstant methodrefConstant)
    {
        visitRefConstant(clazz, methodrefConstant);
    }


    private void visitRefConstant(Clazz clazz, RefConstant methodrefConstant)
    {
        if (shouldBeMarkedAsUsed(methodrefConstant))
        {
            markAsUsed(methodrefConstant);

            markConstant(clazz, methodrefConstant.u2classIndex);
            markConstant(clazz, methodrefConstant.u2nameAndTypeIndex);

            // When compiled with "-target 1.2" or higher, the class or
            // interface actually containing the referenced method may be
            // higher up the hierarchy. Make sure it's marked, in case it
            // isn't used elsewhere.
            methodrefConstant.referencedClassAccept(this);

            // Mark the referenced method itself.
            methodrefConstant.referencedMemberAccept(this);
        }
    }


    public void visitClassConstant(Clazz clazz, ClassConstant classConstant)
    {
        if (shouldBeMarkedAsUsed(classConstant))
        {
            markAsUsed(classConstant);

            markConstant(clazz, classConstant.u2nameIndex);

            // Mark the referenced class itself.
            classConstant.referencedClassAccept(this);
        }
    }


    public void visitNameAndTypeConstant(Clazz clazz, NameAndTypeConstant nameAndTypeConstant)
    {
        if (shouldBeMarkedAsUsed(nameAndTypeConstant))
        {
            markAsUsed(nameAndTypeConstant);

            markConstant(clazz, nameAndTypeConstant.u2nameIndex);
            markConstant(clazz, nameAndTypeConstant.u2descriptorIndex);
        }
    }


    // Implementations for AttributeVisitor.
    // Note that attributes are typically only referenced once, so we don't
    // test if they have been marked already.

    public void visitUnknownAttribute(Clazz clazz, UnknownAttribute unknownAttribute)
    {
        // This is the best we can do for unknown attributes.
        markAsUsed(unknownAttribute);

        markConstant(clazz, unknownAttribute.u2attributeNameIndex);
    }


    public void visitSourceFileAttribute(Clazz clazz, SourceFileAttribute sourceFileAttribute)
    {
        markAsUsed(sourceFileAttribute);