/*******************************************************************************
* 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;
import com.ibm.wala.util.graph.impl.NodeWithNumber;
/**
* Represents a single variable in a fixed-point system.
*/
@SuppressWarnings("rawtypes")
public abstract class AbstractVariable<T extends AbstractVariable> extends NodeWithNumber implements IVariable<T> {
private static int nextHashCode = 0;
private int orderNumber;
private final int hashCode;
protected AbstractVariable() {
this.hashCode = nextHash();
}
@Override
public boolean equals(Object obj) {
// we assume the solver manages these canonically
return this == obj;
}
/**
* I know this is theoretically bad. However,
* <ul>
* <li> we need this to be extremely fast .. it's in the inner loop of lots of stuff.
* <li> these objects will probably only be hashed with each other {@link AbstractVariable}s,
* in which case incrementing hash codes is OK.
* <li> we want determinism, so we don't want to rely on System.identityHashCode
* </ul>
*/
public static synchronized int nextHash() {
return nextHashCode++;
}
@Override
public final int hashCode() {
return hashCode;
}
@Override
public int getOrderNumber() {
return orderNumber;
}
@Override
public void setOrderNumber(int orderNumber) {
this.orderNumber = orderNumber;
}
}