src/proguard/classfile/visitor/ExceptionHandlerFilter.java

/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2014 Eric Lafortune (eric@graphics.cornell.edu)
 *
 * 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.visitor;

import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.ExceptionInfoVisitor;

/**
 * This <code>ExceptionInfoVisitor</code> delegates its visits to another given
 * <code>ExceptionInfoVisitor</code>, but only when the visited exception
 * targets an instruction in the given range of offsets.
 *
 * @author Eric Lafortune
 */
public class ExceptionHandlerFilter
implements   ExceptionInfoVisitor
{
    private final int                  startOffset;
    private final int                  endOffset;
    private final ExceptionInfoVisitor exceptionInfoVisitor;


    /**
     * Creates a new ExceptionHandlerFilter.
     * @param startOffset          the start of the instruction offset range.
     * @param endOffset            the end of the instruction offset range.
     * @param exceptionInfoVisitor the ExceptionInfoVisitor to which visits
     *                             will be delegated.
     */
    public ExceptionHandlerFilter(int                  startOffset,
                                  int                  endOffset,
                                  ExceptionInfoVisitor exceptionInfoVisitor)
    {
        this.startOffset          = startOffset;
        this.endOffset            = endOffset;
        this.exceptionInfoVisitor = exceptionInfoVisitor;
    }


    // Implementations for ExceptionInfoVisitor.

    public void visitExceptionInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, ExceptionInfo exceptionInfo)
    {
        int handlerPC = exceptionInfo.u2handlerPC;
        if (handlerPC >= startOffset &&
            handlerPC <  endOffset)
        {
            exceptionInfoVisitor.visitExceptionInfo(clazz, method, codeAttribute, exceptionInfo);
        }
    }
}