com.ibm.wala.fixpoint.AbstractVariable Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of com.ibm.wala.util Show documentation

T. J. Watson Libraries for Analysis

The newest version!

/*
 * 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. */
public abstract class AbstractVariable> extends NodeWithNumber
    implements IVariable {

  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,
   *
   * 
   *   we need this to be extremely fast .. it's in the inner loop of lots of stuff.
   *   
these objects will probably only be hashed with each other {@code AbstractVariable}s, in
   *       which case incrementing hash codes is OK.
   *   
we want determinism, so we don't want to rely on System.identityHashCode
   * 
   */
  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;
  }
}