ceph/src/boost/boost/pfr/tuple_size.hpp

   1 // Copyright (c) 2016-2020 Antony Polukhin
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6
   7 #ifndef BOOST_PFR_TUPLE_SIZE_HPP
   8 #define BOOST_PFR_TUPLE_SIZE_HPP
   9 #pragma once
  10
  11 #include <boost/pfr/detail/config.hpp>
  12
  13 #include <type_traits>
  14 #include <utility>      // metaprogramming stuff
  15
  16 #include <boost/pfr/detail/sequence_tuple.hpp>
  17 #include <boost/pfr/detail/fields_count.hpp>
  18
  19 /// \file boost/pfr/tuple_size.hpp
  20 /// Contains tuple-like interfaces to get fields count \forcedlink{tuple_size}, \forcedlink{tuple_size_v}.
  21 ///
  22 /// \b Synopsis:
  23 namespace boost { namespace pfr {
  24
  25 /// Has a static const member variable `value` that contains fields count in a T.
  26 /// Works for any T that supports aggregate initialization.
  27 ///
  28 /// \b Example:
  29 /// \code
  30 ///     std::array<int, boost::pfr::tuple_size<my_structure>::value > a;
  31 /// \endcode
  32 template <class T>
  33 using tuple_size = detail::size_t_< boost::pfr::detail::fields_count<T>() >;
  34
  35
  36 /// `tuple_size_v` is a template variable that contains fields count in a T and
  37 /// works for any T that supports aggregate initialization.
  38 ///
  39 /// \b Example:
  40 /// \code
  41 ///     std::array<int, boost::pfr::tuple_size_v<my_structure> > a;
  42 /// \endcode
  43 template <class T>
  44 constexpr std::size_t tuple_size_v = tuple_size<T>::value;
  45
  46 }} // namespace boost::pfr
  47
  48 #endif // BOOST_PFR_TUPLE_SIZE_HPP