| Brian Silverman | af2eaa8 | 2018-08-04 17:28:31 -0700 | [diff] [blame^] | 1 | // Copyright (C) 2003, Fernando Luis Cacciola Carballal. |
| 2 | // Copyright (C) 2014, 2015 Andrzej Krzemienski. |
| 3 | // |
| 4 | // Use, modification, and distribution is subject to the Boost Software |
| 5 | // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
| 6 | // http://www.boost.org/LICENSE_1_0.txt) |
| 7 | // |
| 8 | // See http://www.boost.org/libs/optional for documentation. |
| 9 | // |
| 10 | // You are welcome to contact the author at: |
| 11 | // fernando_cacciola@hotmail.com |
| 12 | // |
| 13 | #ifndef BOOST_NONE_T_17SEP2003_HPP |
| 14 | #define BOOST_NONE_T_17SEP2003_HPP |
| 15 | |
| 16 | namespace boost { |
| 17 | |
| 18 | #ifdef BOOST_OPTIONAL_USE_OLD_DEFINITION_OF_NONE |
| 19 | |
| 20 | namespace detail { struct none_helper{}; } |
| 21 | typedef int detail::none_helper::*none_t ; |
| 22 | |
| 23 | #elif defined BOOST_OPTIONAL_USE_SINGLETON_DEFINITION_OF_NONE |
| 24 | |
| 25 | class none_t {}; |
| 26 | |
| 27 | #else |
| 28 | |
| 29 | struct none_t |
| 30 | { |
| 31 | struct init_tag{}; |
| 32 | explicit none_t(init_tag){} // to disable default constructor |
| 33 | }; |
| 34 | |
| 35 | #endif // old implementation workarounds |
| 36 | |
| 37 | } // namespace boost |
| 38 | |
| 39 | #endif // header guard |