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39 lines
953 B
39 lines
953 B
// Copyright (C) 2003, Fernando Luis Cacciola Carballal. |
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// Copyright (C) 2014, 2015 Andrzej Krzemienski. |
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// |
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// Use, modification, and distribution is subject to the Boost Software |
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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// http://www.boost.org/LICENSE_1_0.txt) |
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// |
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// See http://www.boost.org/libs/optional for documentation. |
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// |
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// You are welcome to contact the author at: |
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// fernando_cacciola@hotmail.com |
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// |
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#ifndef BOOST_NONE_T_17SEP2003_HPP |
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#define BOOST_NONE_T_17SEP2003_HPP |
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namespace boost { |
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#ifdef BOOST_OPTIONAL_USE_OLD_DEFINITION_OF_NONE |
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namespace detail { struct none_helper{}; } |
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typedef int detail::none_helper::*none_t ; |
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#elif defined BOOST_OPTIONAL_USE_SINGLETON_DEFINITION_OF_NONE |
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class none_t {}; |
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#else |
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struct none_t |
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{ |
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struct init_tag{}; |
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explicit none_t(init_tag){} // to disable default constructor |
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}; |
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#endif // old implementation workarounds |
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} // namespace boost |
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#endif // header guard
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