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package com.sun.org.apache.bcel.internal.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
Version:$Id: InstructionComparator.java 1749597 2016-06-21 20:28:51Z ggregory $
/** * 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.<br>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 Instruction * @version $Id: InstructionComparator.java 1749597 2016-06-21 20:28:51Z ggregory $ */
public interface InstructionComparator { InstructionComparator DEFAULT = new InstructionComparator() { @Override public boolean equals( final Instruction i1, final Instruction 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 ); }