// Copyright (C) 2003, Fernando Luis Cacciola Carballal.
|
// Copyright (C) 2014, 2015 Andrzej Krzemienski.
|
//
|
// Use, modification, and distribution is subject to 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)
|
//
|
// See http://www.boost.org/libs/optional for documentation.
|
//
|
// You are welcome to contact the author at:
|
// fernando_cacciola@hotmail.com
|
//
|
#ifndef BOOST_NONE_T_17SEP2003_HPP
|
#define BOOST_NONE_T_17SEP2003_HPP
|
|
#include <boost/config.hpp>
|
|
namespace boost {
|
|
#ifdef BOOST_OPTIONAL_USE_OLD_DEFINITION_OF_NONE
|
|
namespace detail { struct none_helper{}; }
|
typedef int detail::none_helper::*none_t ;
|
|
#elif defined BOOST_OPTIONAL_USE_SINGLETON_DEFINITION_OF_NONE
|
|
class none_t {};
|
|
#else
|
|
struct none_t
|
{
|
struct init_tag{};
|
explicit BOOST_CONSTEXPR none_t(init_tag){} // to disable default constructor
|
};
|
|
#endif // old implementation workarounds
|
|
} // namespace boost
|
|
#endif // header guard
|
