// 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_