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Diffstat (limited to 'boost/mp11/integer_sequence.hpp')
-rw-r--r-- | boost/mp11/integer_sequence.hpp | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/boost/mp11/integer_sequence.hpp b/boost/mp11/integer_sequence.hpp new file mode 100644 index 0000000000..08e312095b --- /dev/null +++ b/boost/mp11/integer_sequence.hpp @@ -0,0 +1,97 @@ +#ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED +#define BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED + +// Copyright 2015, 2017 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 <cstddef> + +namespace boost +{ +namespace mp11 +{ + +// integer_sequence +template<class T, T... I> struct integer_sequence +{ +}; + +// 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; + +// 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 |