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 <iterator>
  10
  11 #ifndef BOOST_STL_INTERFACES_DOXYGEN
  12
  13 #if defined(_MSC_VER) || defined(__GNUC__) && __GNUC__ < 8
  14 #define BOOST_STL_INTERFACES_NO_HIDDEN_FRIEND_CONSTEXPR
  15 #define BOOST_STL_INTERFACES_HIDDEN_FRIEND_CONSTEXPR
  16 #else
  17 #define BOOST_STL_INTERFACES_HIDDEN_FRIEND_CONSTEXPR constexpr
  18 #endif
  19
  20 #if defined(__GNUC__) && __GNUC__ < 9
  21 #define BOOST_STL_INTERFACES_CONCEPT concept bool
  22 #else
  23 #define BOOST_STL_INTERFACES_CONCEPT concept
  24 #endif
  25
  26 #endif
  27
  28
  29 namespace boost { namespace stl_interfaces {
  30     inline namespace v1 {
  31
  32         /** An enumeration used to indicate whether the underlying data have a
  33             contiguous or discontiguous layout when instantiating
  34             `view_interface` and `sequence_container_interface`. */
  35         enum class element_layout : bool {
  36             discontiguous = false,
  37             contiguous = true
  38         };
  39
  40         namespace v1_dtl {
  41             template<typename... T>
  42             using void_t = void;
  43
  44             template<typename Iter>
  45             using iter_difference_t =
  46                 typename std::iterator_traits<Iter>::difference_type;
  47
  48             template<typename Range, typename = void>
  49             struct iterator;
  50             template<typename Range>
  51             struct iterator<
  52                 Range,
  53                 void_t<decltype(std::declval<Range &>().begin())>>
  54             {
  55                 using type = decltype(std::declval<Range &>().begin());
  56             };
  57             template<typename Range>
  58             using iterator_t = typename iterator<Range>::type;
  59
  60             template<typename Range, typename = void>
  61             struct sentinel;
  62             template<typename Range>
  63             struct sentinel<
  64                 Range,
  65                 void_t<decltype(std::declval<Range &>().end())>>
  66             {
  67                 using type = decltype(std::declval<Range &>().end());
  68             };
  69             template<typename Range>
  70             using sentinel_t = typename sentinel<Range>::type;
  71
  72             template<typename Range>
  73             using range_difference_t = iter_difference_t<iterator_t<Range>>;
  74
  75             template<typename Range>
  76             using common_range =
  77                 std::is_same<iterator_t<Range>, sentinel_t<Range>>;
  78
  79             template<typename Range, typename = void>
  80             struct decrementable_sentinel : std::false_type
  81             {
  82             };
  83             template<typename Range>
  84             struct decrementable_sentinel<
  85                 Range,
  86                 void_t<decltype(--std::declval<sentinel_t<Range> &>())>>
  87                 : std::true_type
  88             {
  89             };
  90         }
  91
  92     }
  93 }}
  94
  95 #endif