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//
// detail/std_global.hpp
// ~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#ifndef ASIO_DETAIL_STD_GLOBAL_HPP
#define ASIO_DETAIL_STD_GLOBAL_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#if defined(ASIO_HAS_STD_CALL_ONCE)
#include <exception>
#include <mutex>
#include "asio/detail/push_options.hpp"
namespace asio {
namespace detail {
template <typename T>
struct std_global_impl
{
// Helper function to perform initialisation.
static void do_init()
{
instance_.ptr_ = new T;
}
// Destructor automatically cleans up the global.
~std_global_impl()
{
delete ptr_;
}
static std::once_flag init_once_;
static std_global_impl instance_;
T* ptr_;
};
template <typename T>
std::once_flag std_global_impl<T>::init_once_;
template <typename T>
std_global_impl<T> std_global_impl<T>::instance_;
template <typename T>
T& std_global()
{
std::call_once(std_global_impl<T>::init_once_, &std_global_impl<T>::do_init);
return *std_global_impl<T>::instance_.ptr_;
}
} // namespace detail
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // defined(ASIO_HAS_STD_CALL_ONCE)
#endif // ASIO_DETAIL_STD_GLOBAL_HPP
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