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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.attribute.preverification;
     22 
     23 import proguard.classfile.*;
     24 import proguard.classfile.attribute.CodeAttribute;
     25 import proguard.classfile.attribute.preverification.visitor.StackMapFrameVisitor;
     26 
     27 /**
     28  * This StackMapFrame represents a "same frame" or a "same frame extended".
     29  *
     30  * @author Eric Lafortune
     31  * @noinspection PointlessArithmeticExpression
     32  */
     33 public class SameZeroFrame extends StackMapFrame
     34 {
     35     /**
     36      * Creates an uninitialized SameZeroFrame.
     37      */
     38     public SameZeroFrame()
     39     {
     40     }
     41 
     42 
     43     /**
     44      * Creates a SameZeroFrame with the given tag.
     45      */
     46     public SameZeroFrame(int tag)
     47     {
     48         u2offsetDelta = tag - SAME_ZERO_FRAME;
     49     }
     50 
     51 
     52     // Implementations for StackMapFrame.
     53 
     54     public int getTag()
     55     {
     56         return u2offsetDelta < 64 ?
     57             SAME_ZERO_FRAME + u2offsetDelta :
     58             SAME_ZERO_FRAME_EXTENDED;
     59     }
     60 
     61 
     62     public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, StackMapFrameVisitor stackMapFrameVisitor)
     63     {
     64         stackMapFrameVisitor.visitSameZeroFrame(clazz, method, codeAttribute, offset, this);
     65     }
     66 
     67 
     68     // Implementations for Object.
     69 
     70     public String toString()
     71     {
     72         return super.toString()+"Var: ..., Stack: (empty)";
     73     }
     74 }
     75