1 /*
2  * reserved comment block
3  * DO NOT REMOVE OR ALTER!
4  */
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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
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11  * the License.  You may obtain a copy of the License at
12  *
13  *      http://www.apache.org/licenses/LICENSE-2.0
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15  * Unless required by applicable law or agreed to in writing, software
16  * distributed under the License is distributed on an "AS IS" BASIS,
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18  * See the License for the specific language governing permissions and
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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 
equals( Instruction i1, Instruction i2 )63     boolean equals( Instruction i1, Instruction i2 );
64 }
65