/*******************************************************************************
* Copyright (c) 2002 - 2006 IBM Corporation.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package com.ibm.wala.dataflow.graph;
import com.ibm.wala.fixpoint.BitVectorVariable;
import com.ibm.wala.fixpoint.UnaryOperator;
/**
* Operator OUT = IN
*/
public class BitVectorIdentity extends UnaryOperator<BitVectorVariable> {
private final static BitVectorIdentity SINGLETON = new BitVectorIdentity();
public static BitVectorIdentity instance() {
return SINGLETON;
}
private BitVectorIdentity() {
}
@Override
public byte evaluate(BitVectorVariable lhs, BitVectorVariable rhs) throws IllegalArgumentException {
if (lhs == null) {
throw new IllegalArgumentException("lhs cannot be null");
}
if (lhs.sameValue(rhs)) {
return NOT_CHANGED;
} else {
lhs.copyState(rhs);
return CHANGED;
}
}
@Override
public String toString() {
return "Id ";
}
@Override
public int hashCode() {
return 9902;
}
@Override
public boolean equals(Object o) {
return (o instanceof BitVectorIdentity);
}
/*
* @see com.ibm.wala.fixpoint.UnaryOperator#isIdentity()
*/
@Override
public boolean isIdentity() {
return true;
}
}