nopremover.java

j2me 混淆包,用于混淆j2me的原代码用的

/* $Id: NopRemover.java,v 1.5 2004/10/10 20:56:58 eric Exp $
 *
 * ProGuard -- shrinking, optimization, and obfuscation of Java class files.
 *
 * Copyright (c) 2002-2004 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.optimize.peephole;

import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.editor.*;
import proguard.classfile.instruction.*;
import proguard.classfile.visitor.*;

/**
 * This InstructionVisitor removes all nop instructions that it encounters.
 *
 * @author Eric Lafortune
 */
public class NopRemover implements InstructionVisitor
{
    private CodeAttrInfoEditor codeAttrInfoEditor;


    /**
     * Creates a new NopRemover.
     * @param codeAttrInfoEditor a code editor that can be used for
     *                           accumulating changes to the code.
     */
    public NopRemover(CodeAttrInfoEditor codeAttrInfoEditor)
    {
        this.codeAttrInfoEditor = codeAttrInfoEditor;
    }


    // Implementations for InstructionVisitor.

    public void visitCpInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, CpInstruction cpInstruction) {}
    public void visitVariableInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, VariableInstruction variableInstruction) {}
    public void visitBranchInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, BranchInstruction branchInstruction) {}
    public void visitTableSwitchInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, TableSwitchInstruction tableSwitchInstruction) {}
    public void visitLookUpSwitchInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, LookUpSwitchInstruction lookUpSwitchInstruction) {}


    public void visitSimpleInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, SimpleInstruction simpleInstruction)
    {
        // Check if the instruction is a nop instruction.
        if (simpleInstruction.opcode == InstructionConstants.OP_NOP &&
            !codeAttrInfoEditor.isModified(offset))
        {
            codeAttrInfoEditor.deleteInstruction(offset);
        }
    }
}