3 Defines `boost::hana::union`.
5 @copyright Louis Dionne 2013-2016
6 Distributed under the Boost Software License, Version 1.0.
7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
10 #ifndef BOOST_HANA_UNION_HPP
11 #define BOOST_HANA_UNION_HPP
13 #include <boost/hana/fwd/union.hpp>
15 #include <boost/hana/config.hpp>
16 #include <boost/hana/core/dispatch.hpp>
19 BOOST_HANA_NAMESPACE_BEGIN
21 template <typename Xs, typename Ys>
22 constexpr auto union_t::operator()(Xs&& xs, Ys&& ys) const {
23 using S = typename hana::tag_of<Xs>::type;
24 using Union = BOOST_HANA_DISPATCH_IF(union_impl<S>,
28 return Union::apply(static_cast<Xs&&>(xs), static_cast<Ys&&>(ys));
32 template <typename S, bool condition>
33 struct union_impl<S, when<condition>> : default_ {
34 template <typename ...Args>
35 static constexpr auto apply(Args&& ...) = delete;
37 BOOST_HANA_NAMESPACE_END
39 #endif // !BOOST_HANA_UNION_HPP