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#ifndef BOOST_MP11_DETAIL_MP_DEFER_HPP_INCLUDED
#define BOOST_MP11_DETAIL_MP_DEFER_HPP_INCLUDED
// Copyright 2015-2020, 2023 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/mp11/integral.hpp>
#include <boost/mp11/detail/config.hpp>
namespace boost
{
namespace mp11
{
// mp_if, mp_if_c
namespace detail
{
template<bool C, class T, class... E> struct mp_if_c_impl
{
};
template<class T, class... E> struct mp_if_c_impl<true, T, E...>
{
using type = T;
};
template<class T, class E> struct mp_if_c_impl<false, T, E>
{
using type = E;
};
} // namespace detail
template<bool C, class T, class... E> using mp_if_c = typename detail::mp_if_c_impl<C, T, E...>::type;
template<class C, class T, class... E> using mp_if = typename detail::mp_if_c_impl<static_cast<bool>(C::value), T, E...>::type;
// mp_valid
#if BOOST_MP11_WORKAROUND( BOOST_MP11_INTEL, != 0 ) // tested at 1800
// contributed by Roland Schulz in https://github.com/boostorg/mp11/issues/17
namespace detail
{
template<class...> using void_t = void;
template<class, template<class...> class F, class... T>
struct mp_valid_impl: mp_false {};
template<template<class...> class F, class... T>
struct mp_valid_impl<void_t<F<T...>>, F, T...>: mp_true {};
} // namespace detail
template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<void, F, T...>;
#else
// implementation by Bruno Dutra (by the name is_evaluable)
namespace detail
{
template<template<class...> class F, class... T> struct mp_valid_impl
{
template<template<class...> class G, class = G<T...>> static mp_true check(int);
template<template<class...> class> static mp_false check(...);
using type = decltype(check<F>(0));
};
} // namespace detail
template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<F, T...>::type;
#endif
template<class Q, class... T> using mp_valid_q = mp_valid<Q::template fn, T...>;
// mp_defer
namespace detail
{
template<template<class...> class F, class... T> struct mp_defer_impl
{
using type = F<T...>;
};
struct mp_no_type
{
};
#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
template<template<class...> class F, class... T> struct mp_defer_cuda_workaround
{
using type = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
};
#endif
} // namespace detail
#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
template<template<class...> class F, class... T> using mp_defer = typename detail::mp_defer_cuda_workaround< F, T...>::type;
#else
template<template<class...> class F, class... T> using mp_defer = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
#endif
} // namespace mp11
} // namespace boost
#endif // #ifndef BOOST_MP11_DETAIL_MP_DEFER_HPP_INCLUDED
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