#ifndef HV_SINGLETON_H_
#define HV_SINGLETON_H_

#include <mutex>

#define DISABLE_COPY(Class) \
 Class(const Class&) = delete; \
 Class& operator=(const Class&) = delete;

#define SINGLETON_DECL(Class) \
 public: \
 static Class* instance(); \
 static void exitInstance(); \
 private: \
 DISABLE_COPY(Class) \
 static Class* s_pInstance; \
 static std::once_flag s_initFlag; \
 static std::mutex s_mutex;

#define SINGLETON_IMPL(Class) \
 Class* Class::s_pInstance = NULL; \
 std::once_flag Class::s_initFlag; \
 std::mutex Class::s_mutex; \
 Class* Class::instance() { \
 std::call_once(s_initFlag, []() {s_pInstance = new Class;}); \
	 return s_pInstance; \
 } \
 void Class::exitInstance() { \
 std::lock_guard<std::mutex> lock(s_mutex); \
 if (s_pInstance) { \
 delete s_pInstance; \
 s_pInstance = nullptr; \
 } \
 }

#endif // HV_SINGLETON_H_