/*******************************************************************************
* 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.fixpoint;
/**
* Operator U(n) = U(n) | U(j)
*/
public final class UnaryOr extends UnaryOperator<BooleanVariable> {
private static final UnaryOr SINGLETON = new UnaryOr();
public static UnaryOr instance() {
return UnaryOr.SINGLETON;
}
private UnaryOr() {
}
@Override
public byte evaluate(BooleanVariable lhs, BooleanVariable rhs) throws IllegalArgumentException {
if (lhs == null) {
throw new IllegalArgumentException("lhs == null");
}
boolean old = lhs.getValue();
lhs.or(rhs);
return (lhs.getValue() != old) ? FixedPointConstants.CHANGED : FixedPointConstants.NOT_CHANGED;
}
@Override
public String toString() {
return "OR";
}
@Override
public int hashCode() {
return 9887;
}
@Override
public boolean equals(Object o) {
return (o instanceof UnaryOr);
}
}