stackmaptableattribute.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 library 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 library 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.attribute.preverification;

import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.preverification.visitor.StackMapFrameVisitor;
import proguard.classfile.attribute.visitor.AttributeVisitor;

/**
 * This Attribute represents a stack map table attribute.
 *
 * @author Eric Lafortune
 */
public class StackMapTableAttribute extends Attribute
{
    public int             u2stackMapFramesCount;
    public StackMapFrame[] stackMapFrames;


    /**
     * Creates an uninitialized StackMapTableAttribute.
     */
    public StackMapTableAttribute()
    {
    }


    /**
     * Creates a StackMapTableAttribute with the given stack map frames.
     */
    public StackMapTableAttribute(StackMapFrame[] stackMapFrames)
    {
        this(stackMapFrames.length, stackMapFrames);
    }


    /**
     * Creates a StackMapTableAttribute with the given stack map frames.
     */
    public StackMapTableAttribute(int             stackMapFramesCount,
                                  StackMapFrame[] stackMapFrames)
    {
        this.u2stackMapFramesCount = stackMapFramesCount;
        this.stackMapFrames        = stackMapFrames;
    }


    // Implementations for Attribute.

    public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, AttributeVisitor attributeVisitor)
    {
        attributeVisitor.visitStackMapTableAttribute(clazz, method, codeAttribute, this);
    }


    /**
     * Applies the given stack map frame visitor to all stack map frames.
     */
    public void stackMapFramesAccept(Clazz clazz, Method method, CodeAttribute codeAttribute, StackMapFrameVisitor stackMapFrameVisitor)
    {
        int offset = 0;

        for (int index = 0; index < u2stackMapFramesCount; index++)
        {
            StackMapFrame stackMapFrame = stackMapFrames[index];

            // Note that the byte code offset is computed differently for the
            // first stack map frame.
            offset += stackMapFrame.getOffsetDelta() + (index == 0 ? 0 : 1);

            stackMapFrame.accept(clazz, method, codeAttribute, offset, stackMapFrameVisitor);
        }
    }
}