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

   1 // Copyright (c) 2016-2022 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 #ifndef BOOST_PFR_DETAIL_SIZE_ARRAY_HPP
   7 #define BOOST_PFR_DETAIL_SIZE_ARRAY_HPP
   8 #pragma once
   9
  10 #include <boost/pfr/detail/config.hpp>
  11
  12 #include <cstddef>      // metaprogramming stuff
  13
  14 namespace boost { namespace pfr { namespace detail {
  15
  16 ///////////////////// Array that has the constexpr
  17 template <std::size_t N>
  18 struct size_array {                         // libc++ misses constexpr on operator[]
  19     typedef std::size_t type;
  20     std::size_t data[N];
  21
  22     static constexpr std::size_t size() noexcept { return N; }
  23
  24     constexpr std::size_t count_nonzeros() const noexcept {
  25         std::size_t count = 0;
  26         for (std::size_t i = 0; i < size(); ++i) {
  27             if (data[i]) {
  28                 ++ count;
  29             }
  30         }
  31         return count;
  32     }
  33
  34     constexpr std::size_t count_from_opening_till_matching_parenthis_seq(std::size_t from, std::size_t opening_parenthis, std::size_t closing_parenthis) const noexcept {
  35         if (data[from] != opening_parenthis) {
  36             return 0;
  37         }
  38         std::size_t unclosed_parnthesis = 0;
  39         std::size_t count = 0;
  40         for (; ; ++from) {
  41             if (data[from] == opening_parenthis) {
  42                 ++ unclosed_parnthesis;
  43             } else if (data[from] == closing_parenthis) {
  44                 -- unclosed_parnthesis;
  45             }
  46             ++ count;
  47
  48             if (unclosed_parnthesis == 0) {
  49                 return count;
  50             }
  51         }
  52
  53         return count;
  54     }
  55 };
  56
  57 template <>
  58 struct size_array<0> {                         // libc++ misses constexpr on operator[]
  59     typedef std::size_t type;
  60     std::size_t data[1];
  61
  62     static constexpr std::size_t size() noexcept { return 0; }
  63
  64     constexpr std::size_t count_nonzeros() const noexcept {
  65         return 0;
  66     }
  67 };
  68
  69 template <std::size_t I, std::size_t N>
  70 constexpr std::size_t get(const size_array<N>& a) noexcept {
  71     static_assert(I < N, "====================> Boost.PFR: Array index out of bounds");
  72     return a.data[I];
  73 }
  74
  75
  76
  77 }}} // namespace boost::pfr::detail
  78
  79 #endif // BOOST_PFR_DETAIL_SIZE_ARRAY_HPP