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      1 /*
      2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
      3  *             of Java bytecode.
      4  *
      5  * Copyright (c) 2002-2014 Eric Lafortune (eric (at) graphics.cornell.edu)
      6  *
      7  * This program is free software; you can redistribute it and/or modify it
      8  * under the terms of the GNU General Public License as published by the Free
      9  * Software Foundation; either version 2 of the License, or (at your option)
     10  * any later version.
     11  *
     12  * This program is distributed in the hope that it will be useful, but WITHOUT
     13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     14  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
     15  * more details.
     16  *
     17  * You should have received a copy of the GNU General Public License along
     18  * with this program; if not, write to the Free Software Foundation, Inc.,
     19  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     20  */
     21 package proguard.classfile.visitor;
     22 
     23 import proguard.classfile.*;
     24 import proguard.classfile.attribute.*;
     25 import proguard.classfile.attribute.visitor.ExceptionInfoVisitor;
     26 
     27 /**
     28  * This <code>ExceptionInfoVisitor</code> delegates its visits to another given
     29  * <code>ExceptionInfoVisitor</code>, but only when the visited exception
     30  * targets an instruction in the given range of offsets.
     31  *
     32  * @author Eric Lafortune
     33  */
     34 public class ExceptionHandlerFilter
     35 implements   ExceptionInfoVisitor
     36 {
     37     private final int                  startOffset;
     38     private final int                  endOffset;
     39     private final ExceptionInfoVisitor exceptionInfoVisitor;
     40 
     41 
     42     /**
     43      * Creates a new ExceptionHandlerFilter.
     44      * @param startOffset          the start of the instruction offset range.
     45      * @param endOffset            the end of the instruction offset range.
     46      * @param exceptionInfoVisitor the ExceptionInfoVisitor to which visits
     47      *                             will be delegated.
     48      */
     49     public ExceptionHandlerFilter(int                  startOffset,
     50                                   int                  endOffset,
     51                                   ExceptionInfoVisitor exceptionInfoVisitor)
     52     {
     53         this.startOffset          = startOffset;
     54         this.endOffset            = endOffset;
     55         this.exceptionInfoVisitor = exceptionInfoVisitor;
     56     }
     57 
     58 
     59     // Implementations for ExceptionInfoVisitor.
     60 
     61     public void visitExceptionInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, ExceptionInfo exceptionInfo)
     62     {
     63         int handlerPC = exceptionInfo.u2handlerPC;
     64         if (handlerPC >= startOffset &&
     65             handlerPC <  endOffset)
     66         {
     67             exceptionInfoVisitor.visitExceptionInfo(clazz, method, codeAttribute, exceptionInfo);
     68         }
     69     }
     70 }