/*******************************************************************************
* 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) = true
*/
public final class TrueOperator extends UnaryOperator<BooleanVariable> {
private static final TrueOperator SINGLETON = new TrueOperator();
public static TrueOperator instance() {
return TrueOperator.SINGLETON;
}
private TrueOperator() {
}
@Override
public byte evaluate(BooleanVariable lhs, BooleanVariable rhs) throws IllegalArgumentException {
if (lhs == null) {
throw new IllegalArgumentException("lhs == null");
}
if (lhs.getValue()) {
return NOT_CHANGED;
} else {
lhs.set(true);
return CHANGED;
}
}
@Override
public String toString() {
return "TRUE";
}
@Override
public int hashCode() {
return 9889;
}
@Override
public boolean equals(Object o) {
return (o instanceof TrueOperator);
}
}