ceph/src/boost/boost/histogram/detail/argument_traits.hpp

   1 // Copyright 2019 Hans Dembinski
   2 //
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt
   5 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_HISTOGRAM_DETAIL_ARGUMENT_TRAITS_HPP
   8 #define BOOST_HISTOGRAM_DETAIL_ARGUMENT_TRAITS_HPP
   9
  10 #include <boost/histogram/fwd.hpp>
  11 #include <boost/mp11/algorithm.hpp>
  12 #include <boost/mp11/integral.hpp>
  13 #include <boost/mp11/list.hpp>
  14 #include <tuple>
  15
  16 namespace boost {
  17 namespace histogram {
  18 namespace detail {
  19
  20 template <class T>
  21 struct is_weight_impl : mp11::mp_false {};
  22
  23 template <class T>
  24 struct is_weight_impl<weight_type<T>> : mp11::mp_true {};
  25
  26 template <class T>
  27 using is_weight = is_weight_impl<T>;
  28
  29 template <class T>
  30 struct is_sample_impl : mp11::mp_false {};
  31
  32 template <class T>
  33 struct is_sample_impl<sample_type<T>> : mp11::mp_true {};
  34
  35 template <class T>
  36 using is_sample = is_sample_impl<T>;
  37
  38 template <int Idx, class L>
  39 struct sample_args_impl {
  40   using type = mp11::mp_first<std::decay_t<mp11::mp_at_c<L, (Idx >= 0 ? Idx : 0)>>>;
  41 };
  42
  43 template <class L>
  44 struct sample_args_impl<-1, L> {
  45   using type = std::tuple<>;
  46 };
  47
  48 template <std::size_t NArgs, std::size_t Start, int WeightPos, int SamplePos,
  49           class SampleArgs>
  50 struct argument_traits_holder {
  51   using nargs = mp11::mp_size_t<NArgs>;
  52   using start = mp11::mp_size_t<Start>;
  53   using wpos = mp11::mp_int<WeightPos>;
  54   using spos = mp11::mp_int<SamplePos>;
  55   using sargs = SampleArgs;
  56 };
  57
  58 template <class... Ts>
  59 struct argument_traits_impl {
  60   using list_ = mp11::mp_list<Ts...>;
  61   static constexpr std::size_t size_ = sizeof...(Ts);
  62   static constexpr std::size_t weight_ = mp11::mp_find_if<list_, is_weight>::value;
  63   static constexpr std::size_t sample_ = mp11::mp_find_if<list_, is_sample>::value;
  64   static constexpr int spos_ = (sample_ < size_ ? static_cast<int>(sample_) : -1);
  65   static constexpr int wpos_ = (weight_ < size_ ? static_cast<int>(weight_) : -1);
  66
  67   using type =
  68       argument_traits_holder<(size_ - (weight_ < size_) - (sample_ < size_)),
  69                              (weight_ < size_ && sample_ < size_ &&
  70                                       (weight_ + sample_ < 2)
  71                                   ? 2
  72                                   : ((weight_ == 0 || sample_ == 0) ? 1 : 0)),
  73                              wpos_, spos_, typename sample_args_impl<spos_, list_>::type>;
  74 };
  75
  76 template <class... Ts>
  77 using argument_traits = typename argument_traits_impl<Ts...>::type;
  78
  79 } // namespace detail
  80 } // namespace histogram
  81 } // namespace boost
  82
  83 #endif