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> type_name_impl2()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> type_name_impl1(std::index_sequence<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> type_name()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 65