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 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
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package org.apache.bcel.generic;

Equality of instructions isn't clearly to be defined. You might
wish, for example, to compare whether instructions have the same
meaning. E.g., whether two INVOKEVIRTUALs describe the same
call.

The DEFAULT comparator however, considers two instructions
to be equal if they have same opcode and point to the same indexes
(if any) in the constant pool or the same local variable index. Branch
instructions must have the same target.

See Also:
Instruction/**
 * Equality of instructions isn't clearly to be defined. You might
 * wish, for example, to compare whether instructions have the same
 * meaning. E.g., whether two INVOKEVIRTUALs describe the same
 * call.
 * <p>
 * The DEFAULT comparator however, considers two instructions
 * to be equal if they have same opcode and point to the same indexes
 * (if any) in the constant pool or the same local variable index. Branch
 * instructions must have the same target.
 * </p>
 *
 * @see Instruction
 */
public interface InstructionComparator {

    InstructionComparator DEFAULT = (i1, i2) -> {
        if (i1.getOpcode() == i2.getOpcode()) {
            if (i1 instanceof BranchInstruction) {
             // BIs are never equal to make targeters work correctly (BCEL-195)
                return false;
//                } else if (i1 == i2) { TODO consider adding this shortcut
//                    return true; // this must be AFTER the BI test
            } else if (i1 instanceof ConstantPushInstruction) {
                return ((ConstantPushInstruction) i1).getValue().equals(
                        ((ConstantPushInstruction) i2).getValue());
            } else if (i1 instanceof IndexedInstruction) {
                return ((IndexedInstruction) i1).getIndex() == ((IndexedInstruction) i2)
                        .getIndex();
            } else if (i1 instanceof NEWARRAY) {
                return ((NEWARRAY) i1).getTypecode() == ((NEWARRAY) i2).getTypecode();
            } else {
                return true;
            }
        }
        return false;
    };


    boolean equals( Instruction i1, Instruction i2 );
}