Line data    Source code

       1             : /* Copyright (C) 2019 Wildfire Games.
       2             :  * This file is part of 0 A.D.
       3             :  *
       4             :  * 0 A.D. is free software: you can redistribute it and/or modify
       5             :  * it under the terms of the GNU General Public License as published by
       6             :  * the Free Software Foundation, either version 2 of the License, or
       7             :  * (at your option) any later version.
       8             :  *
       9             :  * 0 A.D. is distributed in the hope that it will be useful,
      10             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12             :  * GNU General Public License for more details.
      13             :  *
      14             :  * You should have received a copy of the GNU General Public License
      15             :  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
      16             :  */
      17             : 
      18             : #ifndef INCLUDED_SINGLETON
      19             : #define INCLUDED_SINGLETON
      20             : 
      21             : #include "lib/debug.h"
      22             : 
      23             : /**
      24             :  * Template base class for singletons.
      25             :  *
      26             :  * Usage:
      27             :  *      class MyClass : public Singleton<MyClass> {};
      28             :  *      MyClass::GetSingleton().MyMethod();
      29             :  *
      30             :  * Modified from http://gamedev.net/reference/articles/article1954.asp
      31             :  */
      32             : template<typename T>
      33             : class Singleton
      34             : {
      35             :     NONCOPYABLE(Singleton);
      36             : public:
      37          19 :     Singleton()
      38             :     {
      39          19 :         ENSURE(!ms_singleton);
      40          19 :         ms_singleton = static_cast<T*>(this);
      41          19 :     }
      42             : 
      43          19 :     ~Singleton()
      44             :     {
      45          19 :         ENSURE(ms_singleton);
      46          19 :         ms_singleton = nullptr;
      47          19 :     }
      48             : 
      49        3276 :     static T& GetSingleton()
      50             :     {
      51        3276 :         ENSURE(ms_singleton);
      52        3276 :         return *ms_singleton;
      53             :     }
      54             : 
      55           0 :     static T* GetSingletonPtr()
      56             :     {
      57           0 :         ENSURE(ms_singleton);
      58           0 :         return ms_singleton;
      59             :     }
      60             : 
      61        7265 :     static bool IsInitialised()
      62             :     {
      63        7265 :         return ms_singleton != nullptr;
      64             :     }
      65             : 
      66             : private:
      67             :     static T* ms_singleton;
      68             : };
      69             : 
      70             : template <typename T>
      71             : T* Singleton<T>::ms_singleton = nullptr;
      72             : 
      73             : #endif // INCLUDED_SINGLETON