ceph/src/boost/boost/stl_interfaces/fwd.hpp

   1 // Copyright (C) 2019 T. Zachary Laine
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See
   4 // accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6 #ifndef BOOST_STL_INTERFACES_FWD_HPP
   7 #define BOOST_STL_INTERFACES_FWD_HPP
   8
   9 #include <boost/stl_interfaces/config.hpp>
  10
  11 #if BOOST_STL_INTERFACES_USE_CONCEPTS
  12 #include <ranges>
  13 #endif
  14 #if defined(__cpp_lib_three_way_comparison)
  15 #include <compare>
  16 #endif
  17
  18 #ifndef BOOST_STL_INTERFACES_DOXYGEN
  19
  20 #if defined(_MSC_VER) || defined(__GNUC__) && __GNUC__ < 8
  21 #define BOOST_STL_INTERFACES_NO_HIDDEN_FRIEND_CONSTEXPR
  22 #define BOOST_STL_INTERFACES_HIDDEN_FRIEND_CONSTEXPR
  23 #else
  24 #define BOOST_STL_INTERFACES_HIDDEN_FRIEND_CONSTEXPR constexpr
  25 #endif
  26
  27 #if defined(__GNUC__) && __GNUC__ < 9
  28 #define BOOST_STL_INTERFACES_CONCEPT concept bool
  29 #else
  30 #define BOOST_STL_INTERFACES_CONCEPT concept
  31 #endif
  32
  33 #endif
  34
  35
  36 namespace boost { namespace stl_interfaces {
  37
  38     /** An enumeration used to indicate whether the underlying data have a
  39         contiguous or discontiguous layout when instantiating `view_interface`
  40         and `sequence_container_interface`. */
  41     enum class element_layout : bool {
  42         discontiguous = false,
  43         contiguous = true
  44     };
  45
  46     BOOST_STL_INTERFACES_NAMESPACE_V1 {
  47
  48         namespace v1_dtl {
  49             template<typename... T>
  50             using void_t = void;
  51
  52             template<typename Iter>
  53             using iter_difference_t =
  54                 typename std::iterator_traits<Iter>::difference_type;
  55
  56             template<typename Range, typename = void>
  57             struct iterator;
  58             template<typename Range>
  59             struct iterator<
  60                 Range,
  61                 void_t<decltype(std::declval<Range &>().begin())>>
  62             {
  63                 using type = decltype(std::declval<Range &>().begin());
  64             };
  65             template<typename Range>
  66             using iterator_t = typename iterator<Range>::type;
  67
  68             template<typename Range, typename = void>
  69             struct sentinel;
  70             template<typename Range>
  71             struct sentinel<
  72                 Range,
  73                 void_t<decltype(std::declval<Range &>().end())>>
  74             {
  75                 using type = decltype(std::declval<Range &>().end());
  76             };
  77             template<typename Range>
  78             using sentinel_t = typename sentinel<Range>::type;
  79
  80             template<typename Range>
  81             using range_difference_t = iter_difference_t<iterator_t<Range>>;
  82
  83             template<typename Range>
  84             using common_range =
  85                 std::is_same<iterator_t<Range>, sentinel_t<Range>>;
  86
  87             template<typename Range, typename = void>
  88             struct decrementable_sentinel : std::false_type
  89             {
  90             };
  91             template<typename Range>
  92             struct decrementable_sentinel<
  93                 Range,
  94                 void_t<decltype(--std::declval<sentinel_t<Range> &>())>>
  95                 : std::true_type
  96             {
  97             };
  98         }
  99
 100     }
 101 }}
 102
 103 #endif