include/Singleton.h

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 * Protocce Engine                                                            *
 * Part of the Crown and Cutlass Project                                      *
 * http://www.crownandcutlass.com                                             *
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// Singleton template

#ifndef _PCCE_SINGLETON_H_
#define _PCCE_SINGLETON_H_

#include "config.h"
#include <boost/shared_ptr.hpp>
#include <boost/thread/mutex.hpp>
#include "Exception.h"

namespace pcce {


  template<class T> class Singleton {
  private:
    static boost::shared_ptr<T> sT;
    static boost::mutex sMutex;
  public:
    static void Initialize() {
      boost::mutex::scoped_lock lock(sMutex);
      if (sT) {
        PCCE_THROW("Attempt to reinitialize singleton class");
      }
      sT.reset(new T());
    }
    static void Shutdown() {
      boost::mutex::scoped_lock lock(sMutex);
      if (!sT) {
        PCCE_THROW("Attempt to shutdown unintialized singleton class");
      }
      if (sT.use_count() != 1) {
        PCCE_THROW("Attempt to shutdown singleton class while still in use");
      }
      sT.reset();
    }
    static boost::shared_ptr<T> Get() {
      boost::mutex::scoped_lock lock(sMutex);
      if (!sT) {
        PCCE_THROW("Attempt to use unintialized singleton class");
      }
      return sT;
    }
    static bool IsInitialized() {
      boost::mutex::scoped_lock lock(sMutex);
      return sT;
    }
  };
  template<class T> boost::shared_ptr<T> Singleton<T>::sT;
  template<class T> boost::mutex Singleton<T>::sMutex;
  

  template<class T> class ScopedSingleton {
  public:
    ScopedSingleton() {
      T::Initialize();
    };
    ~ScopedSingleton() {
      T::Shutdown();
    };
  };

}

#endif

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