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Diffstat (limited to 'boost/hana/union.hpp')
-rw-r--r-- | boost/hana/union.hpp | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/boost/hana/union.hpp b/boost/hana/union.hpp new file mode 100644 index 0000000000..733f7b6bcd --- /dev/null +++ b/boost/hana/union.hpp @@ -0,0 +1,39 @@ +/*! +@file +Defines `boost::hana::union`. + +@copyright Louis Dionne 2013-2016 +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_UNION_HPP +#define BOOST_HANA_UNION_HPP + +#include <boost/hana/fwd/union.hpp> + +#include <boost/hana/config.hpp> +#include <boost/hana/core/dispatch.hpp> + + +BOOST_HANA_NAMESPACE_BEGIN + //! @cond + template <typename Xs, typename Ys> + constexpr auto union_t::operator()(Xs&& xs, Ys&& ys) const { + using S = typename hana::tag_of<Xs>::type; + using Union = BOOST_HANA_DISPATCH_IF(union_impl<S>, + true + ); + + return Union::apply(static_cast<Xs&&>(xs), static_cast<Ys&&>(ys)); + } + //! @endcond + + template <typename S, bool condition> + struct union_impl<S, when<condition>> : default_ { + template <typename ...Args> + static constexpr auto apply(Args&& ...) = delete; + }; +BOOST_HANA_NAMESPACE_END + +#endif // !BOOST_HANA_UNION_HPP |