/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2007 INRIA

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program 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 for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef SIMULATION_SINGLETON_H

#define SIMULATION_SINGLETON_H

namespace ns3 {

/**

 * This singleton class template ensures that the type

 * for which we want a singleton has a lifetime bounded

 * by the simulation lifetime. That it, the underlying

 * type will be automatically deleted upon a users' call

 * to Simulator::Destroy.

 */

template <typename T>

class SimulationSingleton

{

public:

  /**

   * \returns the instance underlying this singleton.

   *

   * This instance will be automatically deleted when the

   * user calls ns3::Simulator::Destroy.

   */

  static T *Get (void);

private:

  static T **GetObject (void);

  static void DeleteObject (void);

};

#include "simulator.h"

namespace ns3 {

template <typename T>

T *

SimulationSingleton<T>::Get (void)

{

  T ** ppobject = GetObject ();

  return *ppobject;

}

template <typename T>

T **

SimulationSingleton<T>::GetObject (void)

{

  static T *pobject = 0;

  if (pobject == 0)

    {

      pobject = new T ();

      Simulator::ScheduleDestroy (&SimulationSingleton<T>::DeleteObject);

    }

  return &pobject;

}

template <typename T>

void

SimulationSingleton<T>::DeleteObject (void)

{

  T **ppobject = GetObject ();

  delete (*ppobject);

  *ppobject = 0;

}

} // namespace ns3

#endif /* SIMULATION_SINGLETON_H */