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- //-----------------------------------------------------------------------------
- // boost variant/detail/has_result_type.hpp header file
- // See http://www.boost.org for updates, documentation, and revision history.
- //-----------------------------------------------------------------------------
- //
- // Copyright (c) 2014-2019 Antony Polukhin
- //
- // 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 BOOST_VARIANT_DETAIL_HAS_RESULT_TYPE_HPP
- #define BOOST_VARIANT_DETAIL_HAS_RESULT_TYPE_HPP
- #include <boost/config.hpp>
- #include <boost/type_traits/remove_reference.hpp>
- namespace boost { namespace detail { namespace variant {
- template <typename T >
- struct has_result_type {
- private:
- typedef char yes;
- typedef struct { char array[2]; } no;
- template<typename C> static yes test(typename boost::remove_reference<typename C::result_type>::type*);
- template<typename C> static no test(...);
- public:
- BOOST_STATIC_CONSTANT(bool, value = sizeof(test<T>(0)) == sizeof(yes));
- };
- }}} // namespace boost::detail::variant
- #endif // BOOST_VARIANT_DETAIL_HAS_RESULT_TYPE_HPP
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