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편집 파일: algorithm.hpp

#ifndef BOOST_MP11_ALGORITHM_HPP_INCLUDED
#define BOOST_MP11_ALGORITHM_HPP_INCLUDED

//  Copyright 2015-2019 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/list.hpp>
#include <boost/mp11/set.hpp>
#include <boost/mp11/integral.hpp>
#include <boost/mp11/utility.hpp>
#include <boost/mp11/function.hpp>
#include <boost/mp11/detail/mp_count.hpp>
#include <boost/mp11/detail/mp_plus.hpp>
#include <boost/mp11/detail/mp_map_find.hpp>
#include <boost/mp11/detail/mp_with_index.hpp>
#include <boost/mp11/detail/mp_fold.hpp>
#include <boost/mp11/detail/mp_min_element.hpp>
#include <boost/mp11/detail/mp_copy_if.hpp>
#include <boost/mp11/detail/mp_remove_if.hpp>
#include <boost/mp11/detail/config.hpp>
#include <boost/mp11/integer_sequence.hpp>
#include <type_traits>
#include <utility>

#if defined(_MSC_VER) || defined(__GNUC__)
# pragma push_macro( "I" )
# undef I
#endif

namespace boost
{
namespace mp11
{

// mp_transform<F, L...>
namespace detail
{

template<template<class...> class F, class... L> struct mp_transform_impl
{
};

template<template<class...> class F, template<class...> class L, class... T> struct mp_transform_impl<F, L<T...>>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )

template<class... U> struct f { using type = F<U...>; };

using type = L<typename f<T>::type...>;

#else

using type = L<F<T>...>;

#endif
};

template<template<class...> class F, template<class...> class L1, class... T1, template<class...> class L2, class... T2> struct mp_transform_impl<F, L1<T1...>, L2<T2...>>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )

template<class... U> struct f { using type = F<U...>; };

using type = L1<typename f<T1, T2>::type...>;

#else

using type = L1<F<T1,T2>...>;

#endif
};

template<template<class...> class F, template<class...> class L1, class... T1, template<class...> class L2, class... T2, template<class...> class L3, class... T3> struct mp_transform_impl<F, L1<T1...>, L2<T2...>, L3<T3...>>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )

template<class... U> struct f { using type = F<U...>; };

using type = L1<typename f<T1, T2, T3>::type...>;

#else

using type = L1<F<T1,T2,T3>...>;

#endif
};

#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)

template<template<class...> class F, template<auto...> class L, auto... A> struct mp_transform_impl<F, L<A...>>
{
    using type = L< F< mp_value<A> >::value... >;
};

template<template<class...> class F, template<auto...> class L1, auto... A1, template<auto...> class L2, auto... A2> struct mp_transform_impl<F, L1<A1...>, L2<A2...>>
{
    using type = L1< F< mp_value<A1>, mp_value<A2> >::value... >;
};

template<template<class...> class F, template<auto...> class L1, auto... A1, template<auto...> class L2, auto... A2, template<auto...> class L3, auto... A3> struct mp_transform_impl<F, L1<A1...>, L2<A2...>, L3<A3...>>
{
    using type = L1< F< mp_value<A1>, mp_value<A2>, mp_value<A3> >::value... >;
};

#endif

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, == 1900 ) || BOOST_MP11_WORKAROUND( BOOST_MP11_GCC, < 40800 )

template<class... L> using mp_same_size_1 = mp_same<mp_size<L>...>;
template<class... L> struct mp_same_size_2: mp_defer<mp_same_size_1, L...> {};

#endif

struct list_size_mismatch
{
};

#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )

template<template<class...> class F, class... L> struct mp_transform_cuda_workaround
{
    using type = mp_if<mp_same<mp_size<L>...>, detail::mp_transform_impl<F, L...>, detail::list_size_mismatch>;
};

#endif

} // namespace detail

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, == 1900 ) || BOOST_MP11_WORKAROUND( BOOST_MP11_GCC, < 40800 )

template<template<class...> class F, class... L> using mp_transform = typename mp_if<typename detail::mp_same_size_2<L...>::type, detail::mp_transform_impl<F, L...>, detail::list_size_mismatch>::type;

#else

#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )

template<template<class...> class F, class... L> using mp_transform = typename detail::mp_transform_cuda_workaround< F, L...>::type::type;

#else

template<template<class...> class F, class... L> using mp_transform = typename mp_if<mp_same<mp_size<L>...>, detail::mp_transform_impl<F, L...>, detail::list_size_mismatch>::type;

#endif

template<class Q, class... L> using mp_transform_q = mp_transform<Q::template fn, L...>;

namespace detail
{

template<template<class...> class F, template<class...> class L1, class... T1, template<class...> class L2, class... T2, template<class...> class L3, class... T3, template<class...> class L4, class... T4, class... L> struct mp_transform_impl<F, L1<T1...>, L2<T2...>, L3<T3...>, L4<T4...>, L...>
{
    using A1 = L1<mp_list<T1, T2, T3, T4>...>;

template<class V, class T> using _f = mp_transform<mp_push_back, V, T>;

using A2 = mp_fold<mp_list<L...>, A1, _f>;

template<class T> using _g = mp_apply<F, T>;

using type = mp_transform<_g, A2>;
};

} // namespace detail

// mp_transform_if<P, F, L...>
namespace detail
{

template<template<class...> class P, template<class...> class F, class... L> struct mp_transform_if_impl
{
    // the stupid quote-unquote dance avoids "pack expansion used as argument for non-pack parameter of alias template"

using Qp = mp_quote<P>;
    using Qf = mp_quote<F>;

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )

template<class... U> struct _f_ { using type = mp_eval_if_q<mp_not<mp_invoke_q<Qp, U...>>, mp_first<mp_list<U...>>, Qf, U...>; };
    template<class... U> using _f = typename _f_<U...>::type;

#else

template<class... U> using _f = mp_eval_if_q<mp_not<mp_invoke_q<Qp, U...>>, mp_first<mp_list<U...>>, Qf, U...>;

#endif

using type = mp_transform<_f, L...>;
};

} // namespace detail

template<template<class...> class P, template<class...> class F, class... L> using mp_transform_if = typename detail::mp_transform_if_impl<P, F, L...>::type;
template<class Qp, class Qf, class... L> using mp_transform_if_q = typename detail::mp_transform_if_impl<Qp::template fn, Qf::template fn, L...>::type;

// mp_filter<P, L...>
namespace detail
{

template<template<class...> class P, class L1, class... L> struct mp_filter_impl
{
    using Qp = mp_quote<P>;

template<class T1, class... T> using _f = mp_if< mp_invoke_q<Qp, T1, T...>, mp_list<T1>, mp_list<> >;

using _t1 = mp_transform<_f, L1, L...>;
    using _t2 = mp_apply<mp_append, _t1>;

using type = mp_assign<L1, _t2>;
};

} // namespace detail

template<template<class...> class P, class... L> using mp_filter = typename detail::mp_filter_impl<P, L...>::type;
template<class Q, class... L> using mp_filter_q = typename detail::mp_filter_impl<Q::template fn, L...>::type;

// mp_fill<L, V>
namespace detail
{

template<class L, class V> struct mp_fill_impl
{
// An error "no type named 'type'" here means that the L argument of mp_fill is not a list
};

template<template<class...> class L, class... T, class V> struct mp_fill_impl<L<T...>, V>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1900 )

template<class...> struct _f { using type = V; };
    using type = L<typename _f<T>::type...>;

#else

template<class...> using _f = V;
    using type = L<_f<T>...>;

#endif
};

#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)

template<template<auto...> class L, auto... A, class V> struct mp_fill_impl<L<A...>, V>
{
    using type = L<((void)A, V::value)...>;
};

#endif

} // namespace detail

template<class L, class V> using mp_fill = typename detail::mp_fill_impl<L, V>::type;

// mp_contains<L, V>
template<class L, class V> using mp_contains = mp_to_bool<mp_count<L, V>>;

// mp_repeat(_c)<L, N>
namespace detail
{

template<class L, std::size_t N> struct mp_repeat_c_impl
{
    using _l1 = typename mp_repeat_c_impl<L, N/2>::type;
    using _l2 = typename mp_repeat_c_impl<L, N%2>::type;

using type = mp_append<_l1, _l1, _l2>;
};

template<class L> struct mp_repeat_c_impl<L, 0>
{
    using type = mp_clear<L>;
};

template<class L> struct mp_repeat_c_impl<L, 1>
{
    using type = L;
};

} // namespace detail

template<class L, std::size_t N> using mp_repeat_c = typename detail::mp_repeat_c_impl<L, N>::type;
template<class L, class N> using mp_repeat = typename detail::mp_repeat_c_impl<L, std::size_t{ N::value }>::type;

// mp_product<F, L...>
namespace detail
{

template<template<class...> class F, class P, class... L> struct mp_product_impl_2
{
};

template<template<class...> class F, class P> struct mp_product_impl_2<F, P>
{
    using type = mp_list<mp_rename<P, F>>;
};

template<template<class...> class F, class P, template<class...> class L1, class... T1, class... L> struct mp_product_impl_2<F, P, L1<T1...>, L...>
{
    using type = mp_append<typename mp_product_impl_2<F, mp_push_back<P, T1>, L...>::type...>;
};

template<template<class...> class F, class... L> struct mp_product_impl
{
};

template<template<class...> class F> struct mp_product_impl<F>
{
    using type = mp_list< F<> >;
};

template<template<class...> class F, class L1, class... L> struct mp_product_impl<F, L1, L...>
{
    using type = mp_assign<L1, typename mp_product_impl_2<F, mp_list<>, L1, L...>::type>;
};

} // namespace detail

template<template<class...> class F, class... L> using mp_product = typename detail::mp_product_impl<F, L...>::type;
template<class Q, class... L> using mp_product_q = typename detail::mp_product_impl<Q::template fn, L...>::type;

// mp_drop(_c)<L, N>
namespace detail
{

template<class L, class L2, class En> struct mp_drop_impl;

template<template<class...> class L, class... T, template<class...> class L2, class... U> struct mp_drop_impl<L<T...>, L2<U...>, mp_true>
{
    template<class... W> static mp_identity<L<W...>> f( U*..., mp_identity<W>*... );

using R = decltype( f( static_cast<mp_identity<T>*>(0) ... ) );

using type = typename R::type;
};

} // namespace detail

template<class L, std::size_t N> using mp_drop_c = mp_assign<L, typename detail::mp_drop_impl<mp_rename<L, mp_list>, mp_repeat_c<mp_list<void>, N>, mp_bool<N <= mp_size<L>::value>>::type>;

template<class L, class N> using mp_drop = mp_drop_c<L, std::size_t{ N::value }>;

// mp_from_sequence<S, F>
namespace detail
{

template<class S, class F> struct mp_from_sequence_impl;

template<template<class T, T... I> class S, class U, U... J, class F> struct mp_from_sequence_impl<S<U, J...>, F>
{
    using type = mp_list_c<U, (F::value + J)...>;
};

} // namespace detail

template<class S, class F = mp_int<0>> using mp_from_sequence = typename detail::mp_from_sequence_impl<S, F>::type;

// mp_iota(_c)<N, F>
template<std::size_t N, std::size_t F = 0> using mp_iota_c = mp_from_sequence<make_index_sequence<N>, mp_size_t<F>>;
template<class N, class F = mp_int<0>> using mp_iota = mp_from_sequence<make_integer_sequence<typename std::remove_const<decltype(N::value)>::type, N::value>, F>;

// mp_at(_c)<L, I>
namespace detail
{

template<class L, std::size_t I> struct mp_at_c_impl;

#if defined(BOOST_MP11_HAS_TYPE_PACK_ELEMENT)

template<template<class...> class L, class... T, std::size_t I> struct mp_at_c_impl<L<T...>, I>
{
    using type = __type_pack_element<I, T...>;
};

#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)

template<template<auto...> class L, auto... A, std::size_t I> struct mp_at_c_impl<L<A...>, I>
{
    using type = __type_pack_element<I, mp_value<A>...>;
};

#endif

#else

template<class L, std::size_t I> struct mp_at_c_impl
{
    using _map = mp_transform<mp_list, mp_iota<mp_size<L> >, mp_rename<L, mp_list>>;
    using type = mp_second<mp_map_find<_map, mp_size_t<I> > >;
};

#endif

#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )

template<class L, std::size_t I> struct mp_at_c_cuda_workaround
{
    using type = mp_if_c<(I < mp_size<L>::value), detail::mp_at_c_impl<L, I>, void>;
};

#endif

} // namespace detail

#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )

template<class L, std::size_t I> using mp_at_c = typename detail::mp_at_c_cuda_workaround< L, I >::type::type;

#else

template<class L, std::size_t I> using mp_at_c = typename mp_if_c<(I < mp_size<L>::value), detail::mp_at_c_impl<L, I>, void>::type;

#endif

template<class L, class I> using mp_at = mp_at_c<L, std::size_t{ I::value }>;

// mp_take(_c)<L, N>
namespace detail
{

template<std::size_t N, class L, class E = void> struct mp_take_c_impl
{
};

template<template<class...> class L, class... T>
struct mp_take_c_impl<0, L<T...>>
{
    using type = L<>;
};

template<template<class...> class L, class T1, class... T>
struct mp_take_c_impl<1, L<T1, T...>>
{
    using type = L<T1>;
};

template<template<class...> class L, class T1, class T2, class... T>
struct mp_take_c_impl<2, L<T1, T2, T...>>
{
    using type = L<T1, T2>;
};

template<template<class...> class L, class T1, class T2, class T3, class... T>
struct mp_take_c_impl<3, L<T1, T2, T3, T...>>
{
    using type = L<T1, T2, T3>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class... T>
struct mp_take_c_impl<4, L<T1, T2, T3, T4, T...>>
{
    using type = L<T1, T2, T3, T4>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class... T>
struct mp_take_c_impl<5, L<T1, T2, T3, T4, T5, T...>>
{
    using type = L<T1, T2, T3, T4, T5>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class... T>
struct mp_take_c_impl<6, L<T1, T2, T3, T4, T5, T6, T...>>
{
    using type = L<T1, T2, T3, T4, T5, T6>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class... T>
struct mp_take_c_impl<7, L<T1, T2, T3, T4, T5, T6, T7, T...>>
{
    using type = L<T1, T2, T3, T4, T5, T6, T7>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class... T>
struct mp_take_c_impl<8, L<T1, T2, T3, T4, T5, T6, T7, T8, T...>>
{
    using type = L<T1, T2, T3, T4, T5, T6, T7, T8>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class... T>
struct mp_take_c_impl<9, L<T1, T2, T3, T4, T5, T6, T7, T8, T9, T...>>
{
    using type = L<T1, T2, T3, T4, T5, T6, T7, T8, T9>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class... T, std::size_t N>
struct mp_take_c_impl<N, L<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T...>, typename std::enable_if<N >= 10>::type>
{
    using type = mp_append<L<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>, typename mp_take_c_impl<N-10, L<T...>>::type>;
};

} // namespace detail

template<class L, std::size_t N> using mp_take_c = mp_assign<L, typename detail::mp_take_c_impl<N, mp_rename<L, mp_list>>::type>;
template<class L, class N> using mp_take = mp_take_c<L, std::size_t{ N::value }>;

// mp_slice(_c)<L, I, J>
template<class L, std::size_t I, std::size_t J> using mp_slice_c = mp_drop_c< mp_take_c<L, J>, I >;
template<class L, class I, class J> using mp_slice = mp_drop< mp_take<L, J>, I >;

// mp_back<L>
template<class L> using mp_back = mp_at_c<L, mp_size<L>::value - 1>;

// mp_pop_back<L>
template<class L> using mp_pop_back = mp_take_c<L, mp_size<L>::value - 1>;

// mp_replace<L, V, W>
namespace detail
{

template<class L, class V, class W> struct mp_replace_impl;

template<template<class...> class L, class... T, class V, class W> struct mp_replace_impl<L<T...>, V, W>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )
    template<class A> struct _f { using type = mp_if<std::is_same<A, V>, W, A>; };
    using type = L<typename _f<T>::type...>;
#else
    template<class A> using _f = mp_if<std::is_same<A, V>, W, A>;
    using type = L<_f<T>...>;
#endif
};

} // namespace detail

template<class L, class V, class W> using mp_replace = typename detail::mp_replace_impl<L, V, W>::type;

// mp_replace_if<L, P, W>
namespace detail
{

template<class L, template<class...> class P, class W> struct mp_replace_if_impl;

template<template<class...> class L, class... T, template<class...> class P, class W> struct mp_replace_if_impl<L<T...>, P, W>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )
    template<class U> struct _f { using type = mp_if<P<U>, W, U>; };
    using type = L<typename _f<T>::type...>;
#else
    template<class U> using _f = mp_if<P<U>, W, U>;
    using type = L<_f<T>...>;
#endif
};

} // namespace detail

template<class L, template<class...> class P, class W> using mp_replace_if = typename detail::mp_replace_if_impl<L, P, W>::type;
template<class L, class Q, class W> using mp_replace_if_q = mp_replace_if<L, Q::template fn, W>;

// mp_copy_if<L, P>
//   in detail/mp_copy_if.hpp

// mp_remove<L, V>
namespace detail
{

template<class L, class V> struct mp_remove_impl;

template<template<class...> class L, class... T, class V> struct mp_remove_impl<L<T...>, V>
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )
    template<class U> struct _f { using type = mp_if<std::is_same<U, V>, mp_list<>, mp_list<U>>; };
    using type = mp_append<L<>, typename _f<T>::type...>;
#else
    template<class U> using _f = mp_if<std::is_same<U, V>, mp_list<>, mp_list<U>>;
    using type = mp_append<L<>, _f<T>...>;
#endif
};

} // namespace detail

template<class L, class V> using mp_remove = typename detail::mp_remove_impl<L, V>::type;

// mp_remove_if<L, P>
//   in detail/mp_remove_if.hpp

// mp_flatten<L, L2 = mp_clear<L>>
namespace detail
{

template<class L2> struct mp_flatten_impl
{
    template<class T> using fn = mp_if<mp_similar<L2, T>, T, mp_list<T>>;
};

} // namespace detail

template<class L, class L2 = mp_clear<L>> using mp_flatten = mp_apply<mp_append, mp_push_front<mp_transform_q<detail::mp_flatten_impl<L2>, L>, mp_clear<L>>>;

// mp_partition<L, P>
namespace detail
{

template<class L, template<class...> class P> struct mp_partition_impl;

template<template<class...> class L, class... T, template<class...> class P> struct mp_partition_impl<L<T...>, P>
{
    using type = L<mp_copy_if<L<T...>, P>, mp_remove_if<L<T...>, P>>;
};

} // namespace detail

template<class L, template<class...> class P> using mp_partition = typename detail::mp_partition_impl<L, P>::type;
template<class L, class Q> using mp_partition_q = mp_partition<L, Q::template fn>;

// mp_sort<L, P>
namespace detail
{

template<class L, template<class...> class P> struct mp_sort_impl;

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T, template<class...> class P> struct mp_sort_impl<L<T...>, P>
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = L<>;
};

#else

template<template<class...> class L, template<class...> class P> struct mp_sort_impl<L<>, P>
{
    using type = L<>;
};

#endif

template<template<class...> class L, class T1, template<class...> class P> struct mp_sort_impl<L<T1>, P>
{
    using type = L<T1>;
};

template<template<class...> class L, class T1, class... T, template<class...> class P> struct mp_sort_impl<L<T1, T...>, P>
{
    template<class U> using F = P<U, T1>;

using part = mp_partition<L<T...>, F>;

using S1 = typename mp_sort_impl<mp_first<part>, P>::type;
    using S2 = typename mp_sort_impl<mp_second<part>, P>::type;

using type = mp_append<mp_push_back<S1, T1>, S2>;
};

} // namespace detail

template<class L, template<class...> class P> using mp_sort = typename detail::mp_sort_impl<L, P>::type;
template<class L, class Q> using mp_sort_q = mp_sort<L, Q::template fn>;

// mp_nth_element(_c)<L, I, P>
namespace detail
{

template<class L, std::size_t I, template<class...> class P> struct mp_nth_element_impl;

template<template<class...> class L, class T1, std::size_t I, template<class...> class P> struct mp_nth_element_impl<L<T1>, I, P>
{
    static_assert( I == 0, "mp_nth_element index out of range" );
    using type = T1;
};

template<template<class...> class L, class T1, class... T, std::size_t I, template<class...> class P> struct mp_nth_element_impl<L<T1, T...>, I, P>
{
    static_assert( I < 1 + sizeof...(T), "mp_nth_element index out of range" );

template<class U> using F = P<U, T1>;

using part = mp_partition<L<T...>, F>;

using L1 = mp_first<part>;
    static std::size_t const N1 = mp_size<L1>::value;

using L2 = mp_second<part>;

#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )

struct detail
    {
        struct mp_nth_element_impl_cuda_workaround
        {
            using type = mp_cond<

mp_bool<(I < N1)>, mp_nth_element_impl<L1, I, P>,
                mp_bool<(I == N1)>, mp_identity<T1>,
                mp_true, mp_nth_element_impl<L2, I - N1 - 1, P>

>;
        };
    };

using type = typename detail::mp_nth_element_impl_cuda_workaround::type::type;

#else

using type = typename mp_cond<

mp_bool<(I < N1)>, mp_nth_element_impl<L1, I, P>,
        mp_bool<(I == N1)>, mp_identity<T1>,
        mp_true, mp_nth_element_impl<L2, I - N1 - 1, P>

>::type;

#endif
};

} // namespace detail

template<class L, std::size_t I, template<class...> class P> using mp_nth_element_c = typename detail::mp_nth_element_impl<L, I, P>::type;
template<class L, class I, template<class...> class P> using mp_nth_element = typename detail::mp_nth_element_impl<L, std::size_t{ I::value }, P>::type;
template<class L, class I, class Q> using mp_nth_element_q = mp_nth_element<L, I, Q::template fn>;

// mp_find<L, V>
namespace detail
{

template<class L, class V> struct mp_find_impl;

#if BOOST_MP11_CLANG && defined( BOOST_MP11_HAS_FOLD_EXPRESSIONS )

struct mp_index_holder
{
    std::size_t i_;
    bool f_;
};

constexpr inline mp_index_holder operator+( mp_index_holder const & v, bool f )
{
    if( v.f_ )
    {
        return v;
    }
    else if( f )
    {
        return { v.i_, true };
    }
    else
    {
        return { v.i_ + 1, false };
    }
}

template<template<class...> class L, class... T, class V> struct mp_find_impl<L<T...>, V>
{
    static constexpr mp_index_holder _v{ 0, false };
    using type = mp_size_t< (_v + ... + std::is_same<T, V>::value).i_ >;
};

#elif !defined( BOOST_MP11_NO_CONSTEXPR )

template<template<class...> class L, class V> struct mp_find_impl<L<>, V>
{
    using type = mp_size_t<0>;
};

#if defined( BOOST_MP11_HAS_CXX14_CONSTEXPR )

constexpr std::size_t cx_find_index( bool const * first, bool const * last )
{
    std::size_t m = 0;

while( first != last && !*first )
    {
        ++m;
        ++first;
    }

return m;
}

#else

constexpr std::size_t cx_find_index( bool const * first, bool const * last )
{
    return first == last || *first? 0: 1 + cx_find_index( first + 1, last );
}

#endif

template<template<class...> class L, class... T, class V> struct mp_find_impl<L<T...>, V>
{
    static constexpr bool _v[] = { std::is_same<T, V>::value... };
    using type = mp_size_t< cx_find_index( _v, _v + sizeof...(T) ) >;
};

#else

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T, class V> struct mp_find_impl<L<T...>, V>
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = mp_size_t<0>;
};

#else

template<template<class...> class L, class V> struct mp_find_impl<L<>, V>
{
    using type = mp_size_t<0>;
};

#endif

template<template<class...> class L, class... T, class V> struct mp_find_impl<L<V, T...>, V>
{
    using type = mp_size_t<0>;
};

template<template<class...> class L, class T1, class... T, class V> struct mp_find_impl<L<T1, T...>, V>
{
    using _r = typename mp_find_impl<mp_list<T...>, V>::type;
    using type = mp_size_t<1 + _r::value>;
};

#endif

} // namespace detail

template<class L, class V> using mp_find = typename detail::mp_find_impl<L, V>::type;

// mp_find_if<L, P>
namespace detail
{

template<class L, template<class...> class P> struct mp_find_if_impl;

#if BOOST_MP11_CLANG && defined( BOOST_MP11_HAS_FOLD_EXPRESSIONS )

template<template<class...> class L, class... T, template<class...> class P> struct mp_find_if_impl<L<T...>, P>
{
    static constexpr mp_index_holder _v{ 0, false };
    using type = mp_size_t< (_v + ... + P<T>::value).i_ >;
};

#elif !defined( BOOST_MP11_NO_CONSTEXPR )

template<template<class...> class L, template<class...> class P> struct mp_find_if_impl<L<>, P>
{
    using type = mp_size_t<0>;
};

template<template<class...> class L, class... T, template<class...> class P> struct mp_find_if_impl<L<T...>, P>
{
    static constexpr bool _v[] = { P<T>::value... };
    using type = mp_size_t< cx_find_index( _v, _v + sizeof...(T) ) >;
};

#else

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T, template<class...> class P> struct mp_find_if_impl<L<T...>, P>
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = mp_size_t<0>;
};

#else

template<template<class...> class L, template<class...> class P> struct mp_find_if_impl<L<>, P>
{
    using type = mp_size_t<0>;
};

#endif

template<class L, template<class...> class P> struct mp_find_if_impl_2
{
    using _r = typename mp_find_if_impl<L, P>::type;
    using type = mp_size_t<1 + _r::value>;
};

template<template<class...> class L, class T1, class... T, template<class...> class P> struct mp_find_if_impl<L<T1, T...>, P>
{
    using type = typename mp_if<P<T1>, mp_identity<mp_size_t<0>>, mp_find_if_impl_2<mp_list<T...>, P>>::type;
};

#endif

} // namespace detail

template<class L, template<class...> class P> using mp_find_if = typename detail::mp_find_if_impl<L, P>::type;
template<class L, class Q> using mp_find_if_q = mp_find_if<L, Q::template fn>;

// mp_reverse<L>
namespace detail
{

template<class L> struct mp_reverse_impl;

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T> struct mp_reverse_impl<L<T...>>
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = L<>;
};

#else

template<template<class...> class L> struct mp_reverse_impl<L<>>
{
    using type = L<>;
};

#endif

template<template<class...> class L, class T1> struct mp_reverse_impl<L<T1>>
{
    using type = L<T1>;
};

template<template<class...> class L, class T1, class T2> struct mp_reverse_impl<L<T1, T2>>
{
    using type = L<T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3> struct mp_reverse_impl<L<T1, T2, T3>>
{
    using type = L<T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4> struct mp_reverse_impl<L<T1, T2, T3, T4>>
{
    using type = L<T4, T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5> struct mp_reverse_impl<L<T1, T2, T3, T4, T5>>
{
    using type = L<T5, T4, T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6> struct mp_reverse_impl<L<T1, T2, T3, T4, T5, T6>>
{
    using type = L<T6, T5, T4, T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7> struct mp_reverse_impl<L<T1, T2, T3, T4, T5, T6, T7>>
{
    using type = L<T7, T6, T5, T4, T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8> struct mp_reverse_impl<L<T1, T2, T3, T4, T5, T6, T7, T8>>
{
    using type = L<T8, T7, T6, T5, T4, T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9> struct mp_reverse_impl<L<T1, T2, T3, T4, T5, T6, T7, T8, T9>>
{
    using type = L<T9, T8, T7, T6, T5, T4, T3, T2, T1>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class... T> struct mp_reverse_impl<L<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T...>>
{
    using type = mp_push_back<typename mp_reverse_impl<L<T...>>::type, T10, T9, T8, T7, T6, T5, T4, T3, T2, T1>;
};

} // namespace detail

template<class L> using mp_reverse = typename detail::mp_reverse_impl<L>::type;

// mp_fold<L, V, F>
//   in detail/mp_fold.hpp

// mp_reverse_fold<L, V, F>
namespace detail
{

template<class L, class V, template<class...> class F> struct mp_reverse_fold_impl;

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T, class V, template<class...> class F> struct mp_reverse_fold_impl<L<T...>, V, F>
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = V;
};

#else

template<template<class...> class L, class V, template<class...> class F> struct mp_reverse_fold_impl<L<>, V, F>
{
    using type = V;
};

#endif

template<template<class...> class L, class T1, class... T, class V, template<class...> class F> struct mp_reverse_fold_impl<L<T1, T...>, V, F>
{
    using rest = typename mp_reverse_fold_impl<L<T...>, V, F>::type;
    using type = F<T1, rest>;
};

template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class... T, class V, template<class...> class F> struct mp_reverse_fold_impl<L<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T...>, V, F>
{
    using rest = typename mp_reverse_fold_impl<L<T...>, V, F>::type;
    using type = F<T1, F<T2, F<T3, F<T4, F<T5, F<T6, F<T7, F<T8, F<T9, F<T10, rest> > > > > > > > > >;
};

} // namespace detail

template<class L, class V, template<class...> class F> using mp_reverse_fold = typename detail::mp_reverse_fold_impl<L, V, F>::type;
template<class L, class V, class Q> using mp_reverse_fold_q = mp_reverse_fold<L, V, Q::template fn>;

// mp_unique<L>
namespace detail
{

template<class L> struct mp_unique_impl;

template<template<class...> class L, class... T> struct mp_unique_impl<L<T...>>
{
    using type = mp_set_push_back<L<>, T...>;
};

} // namespace detail

template<class L> using mp_unique = typename detail::mp_unique_impl<L>::type;

// mp_unique_if<L, P>
namespace detail
{

template<template<class...> class P> struct mp_unique_if_push_back
{
    template<class...> struct impl
    {
    };

template<template<class...> class L, class... Ts, class T>
    struct impl<L<Ts...>, T>
    {
        using type = mp_if<mp_any<P<Ts, T>...>, L<Ts...>, L<Ts..., T>>;
    };

template<class... T> using fn = typename impl<T...>::type;
};

} // namespace detail

template<class L, template<class...> class P>
using mp_unique_if = mp_fold_q<L, mp_clear<L>, detail::mp_unique_if_push_back<P>>;

template<class L, class Q> using mp_unique_if_q = mp_unique_if<L, Q::template fn>;

// mp_all_of<L, P>
template<class L, template<class...> class P> using mp_all_of = mp_bool< mp_count_if<L, P>::value == mp_size<L>::value >;
template<class L, class Q> using mp_all_of_q = mp_all_of<L, Q::template fn>;

// mp_none_of<L, P>
template<class L, template<class...> class P> using mp_none_of = mp_bool< mp_count_if<L, P>::value == 0 >;
template<class L, class Q> using mp_none_of_q = mp_none_of<L, Q::template fn>;

// mp_any_of<L, P>
template<class L, template<class...> class P> using mp_any_of = mp_bool< mp_count_if<L, P>::value != 0 >;
template<class L, class Q> using mp_any_of_q = mp_any_of<L, Q::template fn>;

// mp_replace_at_c<L, I, W>
namespace detail
{

template<class L, class I, class W> struct mp_replace_at_impl
{
    static_assert( I::value >= 0, "mp_replace_at<L, I, W>: I must not be negative" );

template<class T1, class T2> using _p = std::is_same<T2, mp_size_t<I::value>>;
    template<class T1, class T2> using _f = W;

using type = mp_transform_if<_p, _f, L, mp_iota<mp_size<L> > >;
};

} // namespace detail

template<class L, class I, class W> using mp_replace_at = typename detail::mp_replace_at_impl<L, I, W>::type;
template<class L, std::size_t I, class W> using mp_replace_at_c = typename detail::mp_replace_at_impl<L, mp_size_t<I>, W>::type;

//mp_for_each<L>(f)
namespace detail
{

template<class... T, class F> BOOST_MP11_CONSTEXPR F mp_for_each_impl( mp_list<T...>, F && f )
{
    using A = int[sizeof...(T)];
    return (void)A{ ((void)f(T()), 0)... }, std::forward<F>(f);
}

template<class F> BOOST_MP11_CONSTEXPR F mp_for_each_impl( mp_list<>, F && f )
{
    return std::forward<F>(f);
}

} // namespace detail

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, >= 1900 )

// msvc has a limit of 1024

template<class L, class F> BOOST_MP11_CONSTEXPR mp_if_c<mp_size<L>::value <= 1024, F> mp_for_each( F && f )
{
    return detail::mp_for_each_impl( mp_rename<L, mp_list>(), std::forward<F>(f) );
}

template<class L, class F> BOOST_MP11_CONSTEXPR mp_if_c<mp_size<L>::value >= 1025, F> mp_for_each( F && f )
{
    using L2 = mp_rename<L, mp_list>;

using L3 = mp_take_c<L2, 1024>;
    using L4 = mp_drop_c<L2, 1024>;

return mp_for_each<L4>( mp_for_each<L3>( std::forward<F>(f) ) );
}

#else

template<class L, class F> BOOST_MP11_CONSTEXPR F mp_for_each( F && f )
{
    return detail::mp_for_each_impl( mp_rename<L, mp_list>(), std::forward<F>(f) );
}

#endif

// mp_insert<L, I, T...>
template<class L, class I, class... T> using mp_insert = mp_append<mp_take<L, I>, mp_push_front<mp_drop<L, I>, T...>>;

// mp_insert_c<L, I, T...>
template<class L, std::size_t I, class... T> using mp_insert_c = mp_append<mp_take_c<L, I>, mp_push_front<mp_drop_c<L, I>, T...>>;

// mp_erase<L, I, J>
template<class L, class I, class J> using mp_erase = mp_append<mp_take<L, I>, mp_drop<L, J>>;

// mp_erase_c<L, I, J>
template<class L, std::size_t I, std::size_t J> using mp_erase_c = mp_append<mp_take_c<L, I>, mp_drop_c<L, J>>;

// mp_starts_with<L1, L2>
// contributed by Glen Joseph Fernandes (glenjofe@gmail.com)
namespace detail {

template<class L1, class L2>
struct mp_starts_with_impl { };

template<template<class...> class L1, class... T1, template<class...> class L2,
    class... T2>
struct mp_starts_with_impl<L1<T1...>, L2<T2...> > {
    template<class L>
    static mp_false check(L);

template<class... T>
    static mp_true check(mp_list<T2..., T...>);

using type = decltype(check(mp_list<T1...>()));
};

} // namespace detail

template<class L1, class L2>
using mp_starts_with = typename detail::mp_starts_with_impl<L1, L2>::type;

// mp_rotate_left(_c)<L, N>
namespace detail
{

// limit divisor to 1 to avoid division by 0 and give a rotation of 0 for lists containing 0 or 1 elements
template<std::size_t Ln, std::size_t N> using canonical_left_rotation = mp_size_t<N % (Ln == 0? 1: Ln)>;

// perform right rotation as a left rotation by inverting the number of elements to rotate
template<std::size_t Ln, std::size_t N> using canonical_right_rotation = mp_size_t<Ln - N % (Ln == 0? 1: Ln)>;

// avoid errors when rotating fixed-sized lists by using mp_list for the transformation
template<class L, class N, class L2 = mp_rename<L, mp_list>> using mp_rotate_impl = mp_assign<L, mp_append< mp_drop<L2, N>, mp_take<L2, N> >>;

} // namespace detail

template<class L, std::size_t N> using mp_rotate_left_c = detail::mp_rotate_impl<L, detail::canonical_left_rotation<mp_size<L>::value, N>>;
template<class L, class N> using mp_rotate_left = mp_rotate_left_c<L, std::size_t{ N::value }>;

// mp_rotate_right(_c)<L, N>
template<class L, std::size_t N> using mp_rotate_right_c = mp_rotate_left<L, detail::canonical_right_rotation<mp_size<L>::value, N>>;
template<class L, class N> using mp_rotate_right = mp_rotate_right_c<L, std::size_t{ N::value }>;

// mp_min_element<L, P>
// mp_max_element<L, P>
//   in detail/mp_min_element.hpp

// mp_power_set<L>
namespace detail
{

template<class L> struct mp_power_set_impl;

} // namespace detail

template<class L> using mp_power_set = typename detail::mp_power_set_impl<L>::type;

namespace detail
{

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T> struct mp_power_set_impl< L<T...> >
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = L< L<> >;
};

#else

template<template<class...> class L> struct mp_power_set_impl< L<> >
{
    using type = L< L<> >;
};

#endif

template<template<class...> class L, class T1, class... T> struct mp_power_set_impl< L<T1, T...> >
{
    using S1 = mp_power_set< L<T...> >;

template<class L2> using _f = mp_push_front<L2, T1>;

using S2 = mp_transform<_f, S1>;

using type = mp_append< S1, S2 >;
};

} // namespace detail

// mp_partial_sum<L, V, F>
namespace detail
{

template<template<class...> class F> struct mp_partial_sum_impl_f
{
#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1900 )

template<class V, class T> using fn = mp_list<F<mp_first<V>, T>, mp_push_back<mp_second<V>, F<mp_first<V>, T>> >;

#else

template<class V, class T, class N = F<mp_first<V>, T>> using fn = mp_list<N, mp_push_back<mp_second<V>, N>>;

#endif
};

} // namespace detail

template<class L, class V, template<class...> class F> using mp_partial_sum = mp_second<mp_fold_q<L, mp_list<V, mp_clear<L>>, detail::mp_partial_sum_impl_f<F>> >;
template<class L, class V, class Q> using mp_partial_sum_q = mp_partial_sum<L, V, Q::template fn>;

// mp_iterate<V, F, R>
namespace detail
{

template<class V, template<class...> class F, template<class...> class R, class N> struct mp_iterate_impl;

} // namespace detail

template<class V, template<class...> class F, template<class...> class R> using mp_iterate = typename detail::mp_iterate_impl<V, F, R, mp_valid<R, V>>::type;

namespace detail
{

template<class V, template<class...> class F, template<class...> class R> struct mp_iterate_impl<V, F, R, mp_false>
{
    template<class X> using _f = mp_list<F<X>>;
    using type = mp_eval_or<mp_list<>, _f, V>;
};

template<class V, template<class...> class F, template<class...> class R> struct mp_iterate_impl<V, F, R, mp_true>
{
    using type = mp_push_front<mp_iterate<R<V>, F, R>, F<V>>;
};

} // namespace detail

template<class V, class Qf, class Qr> using mp_iterate_q = mp_iterate<V, Qf::template fn, Qr::template fn>;

// mp_pairwise_fold<L, F>
namespace detail
{

template<class L, class Q> using mp_pairwise_fold_impl = mp_transform_q<Q, mp_pop_back<L>, mp_pop_front<L>>;

} // namespace detail

template<class L, class Q> using mp_pairwise_fold_q = mp_eval_if<mp_empty<L>, mp_clear<L>, detail::mp_pairwise_fold_impl, L, Q>;
template<class L, template<class...> class F> using mp_pairwise_fold = mp_pairwise_fold_q<L, mp_quote<F>>;

// mp_sliding_fold<L, N, F>
namespace detail
{

template<class C, class L, class Q, class S> struct mp_sliding_fold_impl;

template<class L, class N, class Q> struct mp_sliding_fold_impl<mp_true, L, N, Q>
{
    static const std::size_t M = mp_size<L>::value - N::value + 1;

template<class I> using F = mp_slice_c<L, I::value, I::value + M>;

using J = mp_transform<F, mp_iota<N>>;

using type = mp_apply<mp_transform_q, mp_push_front<J, Q>>;
};

template<class L, class N, class Q> struct mp_sliding_fold_impl<mp_false, L, N, Q>
{
    using type = mp_clear<L>;
};

} // namespace detail

template<class L, class N, class Q> using mp_sliding_fold_q = typename detail::mp_sliding_fold_impl<mp_bool<(mp_size<L>::value >= N::value)>, L, N, Q>::type;
template<class L, class N, template<class...> class F> using mp_sliding_fold = mp_sliding_fold_q<L, N, mp_quote<F>>;

// mp_intersperse<L, S>
namespace detail
{

template<class L, class S> struct mp_intersperse_impl
{
};

#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )

template<template<class...> class L, class... T, class S> struct mp_intersperse_impl<L<T...>, S>
{
    static_assert( sizeof...(T) == 0, "T... must be empty" );
    using type = L<>;
};

#else

template<template<class...> class L, class S> struct mp_intersperse_impl<L<>, S>
{
    using type = L<>;
};

#endif

template<template<class...> class L, class T1, class... T, class S> struct mp_intersperse_impl<L<T1, T...>, S>
{
    using type = mp_append<L<T1>, L<S, T>...>;
};

} // namespace detail

template<class L, class S> using mp_intersperse = typename detail::mp_intersperse_impl<L, S>::type;

// mp_split<L, S>
namespace detail
{

template<class L, class S, class J> struct mp_split_impl;

} // namespace detail

template<class L, class S> using mp_split = typename detail::mp_split_impl<L, S, mp_find<L, S>>::type;

namespace detail
{

template<class L, class S, class J> using mp_split_impl_ = mp_push_front<mp_split<mp_drop_c<L, J::value + 1>, S>, mp_take<L, J>>;

template<class L, class S, class J> struct mp_split_impl
{
    using type = mp_eval_if_c<mp_size<L>::value == J::value, mp_push_back<mp_clear<L>, L>, mp_split_impl_, L, S, J>;
};

} // namespace detail

// mp_join<L, S>

template<class L, class S> using mp_join = mp_apply<mp_append, mp_intersperse<L, mp_list<S>>>;

} // namespace mp11
} // namespace boost

#if defined(_MSC_VER) || defined(__GNUC__)
# pragma pop_macro( "I" )
#endif

#endif // #ifndef BOOST_MP11_ALGORITHM_HPP_INCLUDED