diff options
Diffstat (limited to 'boost/hana/find_if.hpp')
| -rw-r--r-- | boost/hana/find_if.hpp | 78 |
1 files changed, 15 insertions, 63 deletions
diff --git a/boost/hana/find_if.hpp b/boost/hana/find_if.hpp index 3c4e07fcb0..de9c3d3eea 100644 --- a/boost/hana/find_if.hpp +++ b/boost/hana/find_if.hpp @@ -3,6 +3,7 @@ Defines `boost::hana::find_if`. @copyright Louis Dionne 2013-2017 +@copyright Jason Rice 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) */ @@ -17,19 +18,12 @@ Distributed under the Boost Software License, Version 1.0. #include <boost/hana/bool.hpp> #include <boost/hana/concept/iterable.hpp> #include <boost/hana/concept/searchable.hpp> -#include <boost/hana/concept/sequence.hpp> #include <boost/hana/concept/struct.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/dispatch.hpp> -#include <boost/hana/detail/decay.hpp> -#include <boost/hana/drop_while.hpp> #include <boost/hana/first.hpp> -#include <boost/hana/front.hpp> #include <boost/hana/functional/compose.hpp> -#include <boost/hana/is_empty.hpp> -#include <boost/hana/length.hpp> -#include <boost/hana/not.hpp> -#include <boost/hana/optional.hpp> +#include <boost/hana/index_if.hpp> #include <boost/hana/second.hpp> #include <boost/hana/transform.hpp> @@ -62,68 +56,26 @@ BOOST_HANA_NAMESPACE_BEGIN }; namespace detail { - template <typename Xs, typename Pred, std::size_t i, std::size_t N, bool Done> - struct advance_until; - - template <typename Xs, typename Pred, std::size_t i, std::size_t N> - struct advance_until<Xs, Pred, i, N, false> - : advance_until<Xs, Pred, i + 1, N, static_cast<bool>(detail::decay<decltype( - std::declval<Pred>()(hana::at_c<i>(std::declval<Xs>())) - )>::type::value)> - { }; - - template <typename Xs, typename Pred, std::size_t N> - struct advance_until<Xs, Pred, N, N, false> { - template <typename Ys> - static constexpr auto apply(Ys&&) { - return hana::nothing; - } - }; + template <typename Xs> + struct partial_at { + Xs const& xs; - template <typename Xs, typename Pred, std::size_t i, std::size_t N> - struct advance_until<Xs, Pred, i, N, true> { - template <typename Ys> - static constexpr auto apply(Ys&& ys) { - return hana::just(hana::at_c<i - 1>(static_cast<Ys&&>(ys))); + template <typename I> + constexpr decltype(auto) operator()(I i) const { + return hana::at(xs, i); } }; } - template <typename S> - struct find_if_impl<S, when<Sequence<S>::value>> { - template <typename Xs, typename Pred> - static constexpr auto apply(Xs&& xs, Pred&&) { - constexpr std::size_t N = decltype(hana::length(xs))::value; - return detail::advance_until<Xs&&, Pred&&, 0, N, false>::apply( - static_cast<Xs&&>(xs) - ); - } - }; - - template <typename It> - struct find_if_impl<It, when<hana::Iterable<It>::value && !Sequence<It>::value>> { - template <typename Xs, typename Pred> - static constexpr auto find_if_helper(Xs&& xs, Pred&& pred, hana::true_) { - return hana::just(hana::front( - hana::drop_while(static_cast<Xs&&>(xs), - hana::compose(hana::not_, static_cast<Pred&&>(pred))) - )); - } - - template <typename Xs, typename Pred> - static constexpr auto find_if_helper(Xs&&, Pred&&, hana::false_) { - return hana::nothing; - } - + template <typename Tag> + struct find_if_impl<Tag, when<Iterable<Tag>::value>> { template <typename Xs, typename Pred> static constexpr auto apply(Xs&& xs, Pred&& pred) { - constexpr bool found = !decltype( - hana::is_empty(hana::drop_while(static_cast<Xs&&>(xs), - hana::compose(hana::not_, static_cast<Pred&&>(pred)))) - )::value; - return find_if_impl::find_if_helper(static_cast<Xs&&>(xs), - static_cast<Pred&&>(pred), - hana::bool_<found>{}); + using Result = decltype(hana::index_if( + static_cast<Xs&&>(xs), static_cast<Pred&&>(pred))); + + return hana::transform(Result{}, + detail::partial_at<std::decay_t<Xs>>{static_cast<Xs&&>(xs)}); } }; |