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