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