ceph/src/boost/boost/hana/experimental/type_name.hpp

   1 /*
   2 @file
   3 Defines `boost::hana::experimental::type_name`.
   4
   5 @copyright Louis Dionne 2013-2017
   6 Distributed under the Boost Software License, Version 1.0.
   7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   8  */
   9
  10 #ifndef BOOST_HANA_EXPERIMENTAL_TYPE_NAME_HPP
  11 #define BOOST_HANA_EXPERIMENTAL_TYPE_NAME_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/string.hpp>
  15
  16 #include <cstddef>
  17 #include <utility>
  18
  19
  20 BOOST_HANA_NAMESPACE_BEGIN namespace experimental {
  21     namespace detail {
  22         struct cstring {
  23             char const* ptr;
  24             std::size_t length;
  25         };
  26
  27         // Note: We substract the null terminator from the string sizes below.
  28         template <typename T>
  29         constexpr cstring type_name_impl2() {
  30
  31         #if defined(__clang__)
  32             constexpr char const* pretty_function = __PRETTY_FUNCTION__;
  33             constexpr std::size_t total_size = sizeof(__PRETTY_FUNCTION__) - 1;
  34             constexpr std::size_t prefix_size = sizeof("boost::hana::experimental::detail::cstring boost::hana::experimental::detail::type_name_impl2() [T = ") - 1;
  35             constexpr std::size_t suffix_size = sizeof("]") - 1;
  36         #else
  37             #error "No support for this compiler."
  38         #endif
  39
  40             return {pretty_function + prefix_size, total_size - prefix_size - suffix_size};
  41         }
  42
  43         template <typename T, std::size_t ...i>
  44         auto type_name_impl1(std::index_sequence<i...>) {
  45             constexpr auto name = detail::type_name_impl2<T>();
  46             return hana::string<*(name.ptr + i)...>{};
  47         }
  48     } // end namespace detail
  49
  50     //! @ingroup group-experimental
  51     //! Returns a `hana::string` representing the name of the given type, at
  52     //! compile-time.
  53     //!
  54     //! This only works on Clang (and apparently MSVC, but Hana does not work
  55     //! there as of writing this). Original idea taken from
  56     //! https://github.com/Manu343726/ctti.
  57     template <typename T>
  58     auto type_name() {
  59         constexpr auto name = detail::type_name_impl2<T>();
  60         return detail::type_name_impl1<T>(std::make_index_sequence<name.length>{});
  61     }
  62 } BOOST_HANA_NAMESPACE_END
  63
  64 #endif // !BOOST_HANA_EXPERIMENTAL_TYPE_NAME_HPP