// Copyright (C) 2016 Davis E. King (davis@dlib.net) // License: Boost Software License See LICENSE.txt for the full license. #ifndef DLIB_UTILITY_Hh_ #define DLIB_UTILITY_Hh_ #include <cstddef> /* This header contains back-ports of C++14/17 functions and type traits found in <utility> header of the standard library. */ namespace dlib { template<std::size_t... Ints> struct index_sequence { using type = index_sequence; using value_type = std::size_t; static constexpr std::size_t size() noexcept {return sizeof...(Ints);} }; template<class Sequence1, class Sequence2> struct merge_and_renumber; template<std::size_t... I1, std::size_t... I2> struct merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>> : index_sequence < I1..., (sizeof...(I1) + I2)... > {}; template<std::size_t N> struct make_index_sequence : merge_and_renumber < typename make_index_sequence < N / 2 >::type, typename make_index_sequence < N - N / 2 >::type > {}; template<> struct make_index_sequence<0> : index_sequence<> {}; template<> struct make_index_sequence<1> : index_sequence<0> {}; template<typename... Ts> using index_sequence_for = make_index_sequence<sizeof...(Ts)>; } #endif //DLIB_UTILITY_Hh_