memberreferencefixer.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.classfile.editor;

import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.annotation.*;
import proguard.classfile.attribute.annotation.visitor.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.util.*;
import proguard.classfile.visitor.*;

/**
 * This ClassVisitor fixes constant pool field and method references to
 * fields and methods whose names or descriptors have changed.
 *
 * @author Eric Lafortune
 */
public class MemberReferenceFixer
extends      SimplifiedVisitor
implements   ClassVisitor,
             ConstantVisitor,
             MemberVisitor,
             AttributeVisitor,
             AnnotationVisitor,
             ElementValueVisitor
{
    private static final boolean DEBUG = false;


    private ConstantPoolEditor constantPoolEditor = new ConstantPoolEditor();
    private StackSizeUpdater   stackSizeUpdater   = new StackSizeUpdater();

    // Parameter for the visitor methods.
    private int constantIndex;

    // Return values for the visitor methods.
    private boolean isInterfaceMethod;
    private boolean stackSizesMayHaveChanged;


    // Implementations for ClassVisitor.

    public void visitProgramClass(ProgramClass programClass)
    {
        stackSizesMayHaveChanged = false;

        // Fix the constant pool entries.
        for (int index = 1; index < programClass.u2constantPoolCount; index++)
        {
            Constant constant = programClass.constantPool[index];
            if (constant != null)
            {
                // Fix the entry, replacing it entirely if needed.
                this.constantIndex = index;

                constant.accept(programClass, this);
            }
        }

        // Fix class members.
        programClass.fieldsAccept(this);
        programClass.methodsAccept(this);

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


    // Implementations for ConstantVisitor.

    public void visitAnyConstant(Clazz clazz, Constant constant) {}


    public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant)
    {
        // Do we know the referenced field?
        Member referencedMember = fieldrefConstant.referencedMember;
        if (referencedMember != null)
        {
            Clazz referencedClass = fieldrefConstant.referencedClass;

            // Does it have a new name or type?
            String newName = referencedMember.getName(referencedClass);
            String newType = referencedMember.getDescriptor(referencedClass);

            if (!fieldrefConstant.getName(clazz).equals(newName) ||
                !fieldrefConstant.getType(clazz).equals(newType))
            {
                if (DEBUG)
                {
                    debug(clazz, fieldrefConstant, referencedClass, referencedMember);
                }

                // Update the name and type index.
                fieldrefConstant.u2nameAndTypeIndex =
                    constantPoolEditor.addNameAndTypeConstant((ProgramClass)clazz,
                                                              newName,
                                                              newType);
            }
        }
    }


    public void visitInterfaceMethodrefConstant(Clazz clazz, InterfaceMethodrefConstant interfaceMethodrefConstant)
    {
        // Do we know the referenced interface method?
        Member referencedMember = interfaceMethodrefConstant.referencedMember;
        if (referencedMember != null)
        {
            Clazz referencedClass = interfaceMethodrefConstant.referencedClass;

            // Does it have a new name or type?
            String newName = referencedMember.getName(referencedClass);
            String newType = referencedMember.getDescriptor(referencedClass);

            if (!interfaceMethodrefConstant.getName(clazz).equals(newName) ||
                !interfaceMethodrefConstant.getType(clazz).equals(newType))
            {
                if (DEBUG)
                {
                    debug(clazz, interfaceMethodrefConstant, referencedClass, referencedMember);
                }

                // Update the name and type index.
                interfaceMethodrefConstant.u2nameAndTypeIndex =
                    constantPoolEditor.addNameAndTypeConstant((ProgramClass)clazz,
                                                              newName,
                                                              newType);

                // Remember that the stack sizes of the methods in this class
                // may have changed.
                stackSizesMayHaveChanged = true;
            }

            // Check if this is an interface method.
            isInterfaceMethod = true;
            clazz.constantPoolEntryAccept(interfaceMethodrefConstant.u2classIndex, this);

            // Has the method become a non-interface method?
            if (!isInterfaceMethod)
            {
                if (DEBUG)
                {
                    System.out.println("MemberReferenceFixer:");
                    System.out.println("  Class file     = "+clazz.getName());
                    System.out.println("  Ref class      = "+referencedClass.getName());
                    System.out.println("  Ref method     = "+interfaceMethodrefConstant.getName(clazz)+interfaceMethodrefConstant.getType(clazz));
                    System.out.println("    -> ordinary method");
                }

                // Replace the interface method reference by a method reference.
                ((ProgramClass)clazz).constantPool[this.constantIndex] =
                    new MethodrefConstant(interfaceMethodrefConstant.u2classIndex,
                                          interfaceMethodrefConstant.u2nameAndTypeIndex,
                                          referencedClass,
                                          referencedMember);
            }
        }
    }


    public void visitMethodrefConstant(Clazz clazz, MethodrefConstant methodrefConstant)
    {
        // Do we know the referenced method?
        Member referencedMember = methodrefConstant.referencedMember;
        if (referencedMember != null)
        {
            Clazz referencedClass = methodrefConstant.referencedClass;

            // Does it have a new name or type?
            String newName = referencedMember.getName(referencedClass);
            String newType = referencedMember.getDescriptor(referencedClass);

            if (!methodrefConstant.getName(clazz).equals(newName) ||
                !methodrefConstant.getType(clazz).equals(newType))
            {
                if (DEBUG)
                {
                    debug(clazz, methodrefConstant, referencedClass, referencedMember);
                }

                // Update the name and type index.
                methodrefConstant.u2nameAndTypeIndex =
                    constantPoolEditor.addNameAndTypeConstant((ProgramClass)clazz,
                                                              newName,
                                                              newType);

                // Remember that the stack sizes of the methods in this class
                // may have changed.
                stackSizesMayHaveChanged = true;
            }

            // Check if this is an interface method.