| 123456789101112131415161718192021222324252627282930313233343536373839404142434445 |
- /*!
- @file
- Defines `boost::hana::make`.
- @copyright Louis Dionne 2013-2017
- Distributed under the Boost Software License, Version 1.0.
- (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- */
- #ifndef BOOST_HANA_CORE_MAKE_HPP
- #define BOOST_HANA_CORE_MAKE_HPP
- #include <boost/hana/fwd/core/make.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/default.hpp>
- #include <boost/hana/core/when.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @cond
- template <typename Datatype, typename>
- struct make_impl : make_impl<Datatype, when<true>> { };
- //! @endcond
- template <typename Datatype, bool condition>
- struct make_impl<Datatype, when<condition>> : default_ {
- template <typename ...X>
- static constexpr auto make_helper(int, X&& ...x)
- -> decltype(Datatype(static_cast<X&&>(x)...))
- { return Datatype(static_cast<X&&>(x)...); }
- template <typename ...X>
- static constexpr auto make_helper(long, X&& ...) {
- static_assert((sizeof...(X), false),
- "there exists no constructor for the given data type");
- }
- template <typename ...X>
- static constexpr decltype(auto) apply(X&& ...x)
- { return make_helper(int{}, static_cast<X&&>(x)...); }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_CORE_MAKE_HPP
|
