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// Copyright 2015-2019 Hans Dembinski // // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt // or copy at http://www.boost.org/LICENSE_1_0.txt) #ifndef BOOST_HISTOGRAM_DETAIL_TUPLE_SLICE_HPP #define BOOST_HISTOGRAM_DETAIL_TUPLE_SLICE_HPP #include <boost/mp11/integer_sequence.hpp> #include <tuple> #include <type_traits> namespace boost { namespace histogram { namespace detail { template <std::size_t I, class T, std::size_t... K> decltype(auto) tuple_slice_impl(T&& t, mp11::index_sequence<K...>) { return std::forward_as_tuple(std::get<(I + K)>(std::forward<T>(t))...); } template <std::size_t I, std::size_t N, class Tuple> decltype(auto) tuple_slice(Tuple&& t) { constexpr auto S = std::tuple_size<std::decay_t<Tuple>>::value; static_assert(I + N <= S, "I, N must be a valid subset"); return tuple_slice_impl<I>(std::forward<Tuple>(t), mp11::make_index_sequence<N>{}); } } // namespace detail } // namespace histogram } // namespace boost #endif