/*
 * Copyright 2000 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

package sun.jvm.hotspot.utilities.memo;

/** A memoized object. Override {@link #computeValue} in subclasses;
    call {@link #getValue} in using code. */

public abstract class MemoizedObject {
  private boolean computed;
  private Object value;

  /** Should compute the value of this memoized object. This will only
      be called once, upon the first call to {@link #getValue}. */
  protected abstract Object computeValue();

  /** Public accessor for the memoized value. */
  public Object getValue() {
    if (!computed) {
      value = computeValue();
      computed = true;
    }
    return value;
  }
}
