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- #ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
- #define BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
- // Copyright 2015, 2017, 2019 Peter Dimov.
- //
- // Distributed under the Boost Software License, Version 1.0.
- //
- // See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt
- #include <boost/mp11/version.hpp>
- #include <cstddef>
- #if defined(__has_builtin)
- # if __has_builtin(__make_integer_seq)
- # define BOOST_MP11_HAS_MAKE_INTEGER_SEQ
- # endif
- #endif
- namespace boost
- {
- namespace mp11
- {
- // integer_sequence
- template<class T, T... I> struct integer_sequence
- {
- };
- #if defined(BOOST_MP11_HAS_MAKE_INTEGER_SEQ)
- template<class T, T N> using make_integer_sequence = __make_integer_seq<integer_sequence, T, N>;
- #else
- // detail::make_integer_sequence_impl
- namespace detail
- {
- // iseq_if_c
- template<bool C, class T, class E> struct iseq_if_c_impl;
- template<class T, class E> struct iseq_if_c_impl<true, T, E>
- {
- using type = T;
- };
- template<class T, class E> struct iseq_if_c_impl<false, T, E>
- {
- using type = E;
- };
- template<bool C, class T, class E> using iseq_if_c = typename iseq_if_c_impl<C, T, E>::type;
- // iseq_identity
- template<class T> struct iseq_identity
- {
- using type = T;
- };
- template<class S1, class S2> struct append_integer_sequence;
- template<class T, T... I, T... J> struct append_integer_sequence<integer_sequence<T, I...>, integer_sequence<T, J...>>
- {
- using type = integer_sequence< T, I..., ( J + sizeof...(I) )... >;
- };
- template<class T, T N> struct make_integer_sequence_impl;
- template<class T, T N> struct make_integer_sequence_impl_
- {
- private:
- static_assert( N >= 0, "make_integer_sequence<T, N>: N must not be negative" );
- static T const M = N / 2;
- static T const R = N % 2;
- using S1 = typename make_integer_sequence_impl<T, M>::type;
- using S2 = typename append_integer_sequence<S1, S1>::type;
- using S3 = typename make_integer_sequence_impl<T, R>::type;
- using S4 = typename append_integer_sequence<S2, S3>::type;
- public:
- using type = S4;
- };
- template<class T, T N> struct make_integer_sequence_impl: iseq_if_c<N == 0, iseq_identity<integer_sequence<T>>, iseq_if_c<N == 1, iseq_identity<integer_sequence<T, 0>>, make_integer_sequence_impl_<T, N> > >
- {
- };
- } // namespace detail
- // make_integer_sequence
- template<class T, T N> using make_integer_sequence = typename detail::make_integer_sequence_impl<T, N>::type;
- #endif // defined(BOOST_MP11_HAS_MAKE_INTEGER_SEQ)
- // index_sequence
- template<std::size_t... I> using index_sequence = integer_sequence<std::size_t, I...>;
- // make_index_sequence
- template<std::size_t N> using make_index_sequence = make_integer_sequence<std::size_t, N>;
- // index_sequence_for
- template<class... T> using index_sequence_for = make_integer_sequence<std::size_t, sizeof...(T)>;
- } // namespace mp11
- } // namespace boost
- #endif // #ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
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