timer_manager.h

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef TIMER_MANAGER_H
#define TIMER_MANAGER_H
 
#include "../stdafx.h"
 
template <typename TTimerType>
class BaseTimer;
 
template <typename TTimerType>
class TimerManager {
public:
  using TPeriod = typename TTimerType::TPeriod;
  using TElapsed = typename TTimerType::TElapsed;
 
  /* Avoid copying this object; it is a singleton object. */
  TimerManager(TimerManager const &) = delete;
  TimerManager &operator=(TimerManager const &) = delete;
 
  static void RegisterTimer(BaseTimer<TTimerType> &timer)
  {
#ifdef WITH_ASSERT
    Validate(timer.period);
#endif /* WITH_ASSERT */
    GetTimers().insert(&timer);
  }
 
  static void UnregisterTimer(BaseTimer<TTimerType> &timer)
  {
    GetTimers().erase(&timer);
  }
 
  static void ChangeRegisteredTimerPeriod(BaseTimer<TTimerType> &timer, TPeriod new_period)
  {
    /* Unregistration and re-registration is necessary because the period is used as the sort key in base_timer_sorter */
    UnregisterTimer(timer);
    timer.period = new_period;
    RegisterTimer(timer);
  }
 
#ifdef WITH_ASSERT
  static void Validate(TPeriod period);
#endif /* WITH_ASSERT */
 
  static bool Elapsed(TElapsed value);
 
private:
  struct base_timer_sorter {
    bool operator() (BaseTimer<TTimerType> *a, BaseTimer<TTimerType> *b) const
    {
      if (a->period == b->period) return a < b;
      return a->period < b->period;
    }
  };
 
  static std::set<BaseTimer<TTimerType> *, base_timer_sorter> &GetTimers()
  {
    static std::set<BaseTimer<TTimerType> *, base_timer_sorter> timers;
    return timers;
  }
};
 
#endif /* TIMER_MANAGER_H */