Singleton.hpp

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// ANNA - Anna is Not Nothingness Anymore                                                         //
//                                                                                                //
// (c) Copyright 2005-2015 Eduardo Ramos Testillano & Francisco Ruiz Rayo                         //
//                                                                                                //
// See project site at http://redmine.teslayout.com/projects/anna-suite                           //
// See accompanying file LICENSE or copy at http://www.teslayout.com/projects/public/anna.LICENSE //


#ifndef anna_core_Singleton_hpp
#define anna_core_Singleton_hpp

#include <typeinfo>

#include <anna/core/mt/Mutex.hpp>
#include <anna/core/mt/Guard.hpp>

namespace anna {

template <class T> class Singleton {
public:
  static T& instantiate() { return *alloc(true); }

  static void release() { alloc(false); }

private:
  static T* alloc(const bool allocate) {
    static Mutex mutex;
    static T* result(NULL);

    if(allocate == true) {
      if(result == NULL) {
        Guard guard(mutex, "Singleton<T>::allocate");

        if(result == NULL)
          result = new T;
      }
    } else {
      if(result != NULL) {
        Guard guard(mutex, "Singleton<T>::deallocate");

        if(result != NULL) {
          delete result;
          result = NULL;
        }
      }
    }

    return result;
  }
};

} //namespace anna

#endif