1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.bcel.internal.generic;
  23 
  24 /**
  25  * Equality of instructions isn't clearly to be defined. You might
  26  * wish, for example, to compare whether instructions have the same
  27  * meaning. E.g., whether two INVOKEVIRTUALs describe the same
  28  * call.
  29  * <p>
  30  * The DEFAULT comparator however, considers two instructions
  31  * to be equal if they have same opcode and point to the same indexes
  32  * (if any) in the constant pool or the same local variable index. Branch
  33  * instructions must have the same target.
  34  * </p>
  35  *
  36  * @see Instruction
  37  */
  38 public interface InstructionComparator {
  39 
  40     InstructionComparator DEFAULT = (i1, i2) -> {
  41         if (i1.getOpcode() == i2.getOpcode()) {
  42             if (i1 instanceof BranchInstruction) {
  43              // BIs are never equal to make targeters work correctly (BCEL-195)
  44                 return false;
  45 //                } else if (i1 == i2) { TODO consider adding this shortcut
  46 //                    return true; // this must be AFTER the BI test
  47             } else if (i1 instanceof ConstantPushInstruction) {
  48                 return ((ConstantPushInstruction) i1).getValue().equals(
  49                         ((ConstantPushInstruction) i2).getValue());
  50             } else if (i1 instanceof IndexedInstruction) {
  51                 return ((IndexedInstruction) i1).getIndex() == ((IndexedInstruction) i2)
  52                         .getIndex();
  53             } else if (i1 instanceof NEWARRAY) {
  54                 return ((NEWARRAY) i1).getTypecode() == ((NEWARRAY) i2).getTypecode();
  55             } else {
  56                 return true;
  57             }
  58         }
  59         return false;
  60     };
  61 
  62 
  63     boolean equals( Instruction i1, Instruction i2 );
  64 }