1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 package com.sun.org.apache.bcel.internal.generic;
   6 
   7 /* ====================================================================
   8  * The Apache Software License, Version 1.1
   9  *
  10  * Copyright (c) 2001 The Apache Software Foundation.  All rights
  11  * reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  *
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  *
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in
  22  *    the documentation and/or other materials provided with the
  23  *    distribution.
  24  *
  25  * 3. The end-user documentation included with the redistribution,
  26  *    if any, must include the following acknowledgment:
  27  *       "This product includes software developed by the
  28  *        Apache Software Foundation (http://www.apache.org/)."
  29  *    Alternately, this acknowledgment may appear in the software itself,
  30  *    if and wherever such third-party acknowledgments normally appear.
  31  *
  32  * 4. The names "Apache" and "Apache Software Foundation" and
  33  *    "Apache BCEL" must not be used to endorse or promote products
  34  *    derived from this software without prior written permission. For
  35  *    written permission, please contact apache@apache.org.
  36  *
  37  * 5. Products derived from this software may not be called "Apache",
  38  *    "Apache BCEL", nor may "Apache" appear in their name, without
  39  *    prior written permission of the Apache Software Foundation.
  40  *
  41  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  42  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  43  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  44  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  45  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  46  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  47  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  48  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  49  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  50  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  51  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  * ====================================================================
  54  *
  55  * This software consists of voluntary contributions made by many
  56  * individuals on behalf of the Apache Software Foundation.  For more
  57  * information on the Apache Software Foundation, please see
  58  * <http://www.apache.org/>.
  59  */
  60 
  61 /**
  62  * Equality of instructions isn't clearly to be defined. You might
  63  * wish, for example, to compare whether instructions have the same
  64  * meaning. E.g., whether two INVOKEVIRTUALs describe the same
  65  * call.<br>The DEFAULT comparator however, considers two instructions
  66  * to be equal if they have same opcode and point to the same indexes
  67  * (if any) in the constant pool or the same local variable index. Branch
  68  * instructions must have the same target.
  69  *
  70  * @see Instruction
  71  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
  72  */
  73 public interface InstructionComparator {
  74   public static final InstructionComparator DEFAULT =
  75     new InstructionComparator() {
  76         public boolean equals(Instruction i1, Instruction i2) {
  77           if(i1.opcode == i2.opcode) {
  78             if(i1 instanceof Select) {
  79               InstructionHandle[] t1 = ((Select)i1).getTargets();
  80               InstructionHandle[] t2 = ((Select)i2).getTargets();
  81 
  82               if(t1.length == t2.length) {
  83                 for(int i = 0; i < t1.length; i++) {
  84                   if(t1[i] != t2[i]) {
  85                     return false;
  86                   }
  87                 }
  88 
  89                 return true;
  90               }
  91             } else if(i1 instanceof BranchInstruction) {
  92               return ((BranchInstruction)i1).target ==
  93                 ((BranchInstruction)i2).target;
  94             } else if(i1 instanceof ConstantPushInstruction) {
  95               return ((ConstantPushInstruction)i1).getValue().
  96                 equals(((ConstantPushInstruction)i2).getValue());
  97             } else if(i1 instanceof IndexedInstruction) {
  98               return ((IndexedInstruction)i1).getIndex() ==
  99                 ((IndexedInstruction)i2).getIndex();
 100             } else if(i1 instanceof NEWARRAY) {
 101               return ((NEWARRAY)i1).getTypecode() == ((NEWARRAY)i2).getTypecode();
 102             } else {
 103               return true;
 104             }
 105           }
 106 
 107           return false;
 108         }
 109       };
 110 
 111   public boolean equals(Instruction i1, Instruction i2);
 112 }