diff options
Diffstat (limited to 'boost/hana/experimental/types.hpp')
| -rw-r--r-- | boost/hana/experimental/types.hpp | 32 |
1 files changed, 6 insertions, 26 deletions
diff --git a/boost/hana/experimental/types.hpp b/boost/hana/experimental/types.hpp index 86d9ddc957..75ae99e4f6 100644 --- a/boost/hana/experimental/types.hpp +++ b/boost/hana/experimental/types.hpp @@ -14,6 +14,7 @@ Distributed under the Boost Software License, Version 1.0. #include <boost/hana/concept/metafunction.hpp> #include <boost/hana/config.hpp> #include <boost/hana/detail/any_of.hpp> +#include <boost/hana/detail/type_at.hpp> #include <boost/hana/fwd/at.hpp> #include <boost/hana/fwd/contains.hpp> #include <boost/hana/fwd/core/tag_of.hpp> @@ -43,8 +44,6 @@ BOOST_HANA_NAMESPACE_BEGIN struct types_tag; - ////////////////////////////////////////////////////////////////////// - template <typename ...T> struct types { }; } // end namespace experimental @@ -88,30 +87,13 @@ BOOST_HANA_NAMESPACE_BEGIN apply(hana::experimental::types<T...> const&, F const&) { return {}; } }; - namespace types_detail { - template <std::size_t I, typename T> - struct elt { using type = T; }; - - template <typename Indices, typename ...T> - struct indexer; - - template <std::size_t ...I, typename ...T> - struct indexer<std::index_sequence<I...>, T...> - : elt<I, T>... - { }; - - template <std::size_t I, typename T> - elt<I, T> get_elt(elt<I, T> const&); - } - // Iterable template <> struct at_impl<hana::experimental::types_tag> { template <typename ...T, typename N> static constexpr auto apply(hana::experimental::types<T...> const&, N const&) { - using Indexer = types_detail::indexer<std::make_index_sequence<sizeof...(T)>, T...>; - using Nth = typename decltype(types_detail::get_elt<N::value>(Indexer{}))::type; + using Nth = typename detail::type_at<N::value, T...>::type; return hana::type<Nth>{}; } }; @@ -126,18 +108,16 @@ BOOST_HANA_NAMESPACE_BEGIN template <> struct drop_front_impl<hana::experimental::types_tag> { - template <std::size_t n, typename Indexer, std::size_t ...i> - static hana::experimental::types< - typename decltype(types_detail::get_elt<i + n>(Indexer{}))::type... - > helper(std::index_sequence<i...>); + template <std::size_t n, typename ...T, std::size_t ...i> + static hana::experimental::types<typename detail::type_at<i + n, T...>::type...> + helper(std::index_sequence<i...>); template <typename ...T, typename N> static constexpr auto apply(hana::experimental::types<T...> const&, N const&) { constexpr std::size_t n = N::value > sizeof...(T) ? sizeof...(T) : N::value; using Indices = std::make_index_sequence<sizeof...(T) - n>; - using Indexer = types_detail::indexer<std::make_index_sequence<sizeof...(T)>, T...>; - return decltype(helper<n, Indexer>(Indices{})){}; + return decltype(helper<n, T...>(Indices{})){}; } }; |