ceph/src/boost/boost/pfr/detail/tie_from_structure_tuple.hpp

   1 // Copyright (c) 2018 Adam Butcher, Antony Polukhin
   2 // Copyright (c) 2019-2020 Antony Polukhin
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_PFR_DETAIL_TIE_FROM_STRUCTURE_TUPLE_HPP
   8 #define BOOST_PFR_DETAIL_TIE_FROM_STRUCTURE_TUPLE_HPP
   9 #pragma once
  10
  11 #include <boost/pfr/detail/config.hpp>
  12
  13 #include <boost/pfr/detail/core.hpp>
  14
  15 #include <boost/pfr/detail/stdtuple.hpp>
  16 #include <boost/pfr/tuple_size.hpp>
  17 #include <boost/pfr/detail/make_integer_sequence.hpp>
  18
  19 #include <tuple>
  20
  21 namespace boost { namespace pfr { namespace detail {
  22
  23 /// \brief A `std::tuple` capable of de-structuring assignment used to support
  24 /// a tie of multiple lvalue references to fields of an aggregate T.
  25 ///
  26 /// \sa boost::pfr::tie_from_structure
  27 template <typename... Elements>
  28 struct tie_from_structure_tuple : std::tuple<Elements&...> {
  29     using base = std::tuple<Elements&...>;
  30     using base::base;
  31
  32     template <typename T>
  33     constexpr tie_from_structure_tuple& operator= (T const& t) {
  34         base::operator=(
  35             detail::make_stdtiedtuple_from_tietuple(
  36                 detail::tie_as_tuple(t),
  37                 detail::make_index_sequence<tuple_size_v<T>>()));
  38         return *this;
  39     }
  40 };
  41
  42 }}} // boost::pfr::detail
  43
  44 #endif // BOOST_PFR_DETAIL_TIE_FROM_STRUCTURE_TUPLE_HPP