ceph/src/boost/boost/histogram/detail/array_wrapper.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_ARRAY_WRAPPER_HPP
   8 #define BOOST_HISTOGRAM_DETAIL_ARRAY_WRAPPER_HPP
   9
  10 #include <boost/core/nvp.hpp>
  11 #include <boost/histogram/detail/span.hpp>
  12 #include <boost/histogram/detail/static_if.hpp>
  13 #include <boost/mp11/function.hpp>
  14 #include <boost/mp11/utility.hpp>
  15 #include <type_traits>
  16
  17 namespace boost {
  18 namespace histogram {
  19 namespace detail {
  20
  21 template <class T, class = decltype(&T::template save_array<int>)>
  22 struct has_save_array_impl;
  23
  24 template <class T, class = decltype(&T::template load_array<int>)>
  25 struct has_load_array_impl;
  26
  27 template <class T>
  28 using has_array_optimization = mp11::mp_or<mp11::mp_valid<has_save_array_impl, T>,
  29                                            mp11::mp_valid<has_load_array_impl, T>>;
  30
  31 template <class T>
  32 struct array_wrapper {
  33   using pointer = T*;
  34
  35   pointer ptr;
  36   std::size_t size;
  37
  38   template <class Archive>
  39   void serialize(Archive& ar, unsigned /* version */) {
  40     static_if_c<(has_array_optimization<Archive>::value &&
  41                  std::is_trivially_copyable<T>::value)>(
  42         [this](auto& ar) {
  43           // cannot use and therefore bypass save_array / load_array interface, because
  44           // it requires exact type boost::serialization::array_wrapper<T>
  45           static_if_c<Archive::is_loading::value>(
  46               [this](auto& ar) { ar.load_binary(this->ptr, sizeof(T) * this->size); },
  47               [this](auto& ar) { ar.save_binary(this->ptr, sizeof(T) * this->size); },
  48               ar);
  49         },
  50         [this](auto& ar) {
  51           for (auto&& x : boost::histogram::detail::make_span(this->ptr, this->size))
  52             ar& make_nvp("item", x);
  53         },
  54         ar);
  55   }
  56 };
  57
  58 template <class T>
  59 auto make_array_wrapper(T* t, std::size_t s) {
  60   return array_wrapper<T>{t, s};
  61 }
  62
  63 } // namespace detail
  64 } // namespace histogram
  65 } // namespace boost
  66
  67 #endif