/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.math.ode.sampling;


/**
 * This class is a step handler that does nothing.

 * <p>This class is provided as a convenience for users who are only
 * interested in the final state of an integration and not in the
 * intermediate steps. Its handleStep method does nothing.</p>
 *
 * <p>Since this class has no internal state, it is implemented using
 * the Singleton design pattern. This means that only one instance is
 * ever created, which can be retrieved using the getInstance
 * method. This explains why there is no public constructor.</p>
 *
 * @see StepHandler
 * @version $Revision$ $Date$
 * @since 1.2
 */

public class DummyStepHandler implements StepHandler {

  /** Private constructor.
   * The constructor is private to prevent users from creating
   * instances (Singleton design-pattern).
   */
  private DummyStepHandler() {
  }

  /** Get the only instance.
   * @return the only instance
   */
  public static DummyStepHandler getInstance() {
    return instance;
  }

  /** Determines whether this handler needs dense output.
   * Since this handler does nothing, it does not require dense output.
   * @return always false
   */
  public boolean requiresDenseOutput() {
    return false;
  }

  /** Reset the step handler.
   * Initialize the internal data as required before the first step is
   * handled.
   */
  public void reset() {
  }

  /**
   * Handle the last accepted step.
   * This method does nothing in this class.
   * @param interpolator interpolator for the last accepted step. For
   * efficiency purposes, the various integrators reuse the same
   * object on each call, so if the instance wants to keep it across
   * all calls (for example to provide at the end of the integration a
   * continuous model valid throughout the integration range), it
   * should build a local copy using the clone method and store this
   * copy.
   * @param isLast true if the step is the last one
   */
  public void handleStep(final StepInterpolator interpolator, final boolean isLast) {
  }

  /** The only instance. */
  private static final DummyStepHandler instance = new DummyStepHandler();

}
