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#ifndef BOOST_MP11_DETAIL_MP_FRONT_HPP_INCLUDED
#define BOOST_MP11_DETAIL_MP_FRONT_HPP_INCLUDED
// Copyright 2015-2023 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/detail/mp_value.hpp>
#include <boost/mp11/detail/config.hpp>
namespace boost
{
namespace mp11
{
// mp_front<L>
namespace detail
{
template<class L> struct mp_front_impl
{
// An error "no type named 'type'" here means that the argument to mp_front
// is either not a list, or is an empty list
};
template<template<class...> class L, class T1, class... T> struct mp_front_impl<L<T1, T...>>
{
using type = T1;
};
#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
template<template<auto...> class L, auto A1, auto... A> struct mp_front_impl<L<A1, A...>>
{
using type = mp_value<A1>;
};
#endif
} // namespace detail
template<class L> using mp_front = typename detail::mp_front_impl<L>::type;
} // namespace mp11
} // namespace boost
#endif // #ifndef BOOST_MP11_DETAIL_MP_FRONT_HPP_INCLUDED
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