Meta.hpp

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// Copyright 2022 Bernhard Manfred Gruber
// SPDX-License-Identifier: MPL-2.0
 
#pragma once
 
#include "macros.hpp"
 
#include <boost/mp11.hpp>
 
namespace llama
{
    // make mp11 directly available in the llama namespace
    using namespace boost::mp11;
 
    namespace internal
    {
        // adapted from boost::mp11, but with LLAMA_FN_HOST_ACC_INLINE
        template<template<typename...> typename L, typename... T, typename F>
        // NOLINTNEXTLINE(readability-identifier-naming)
        LLAMA_FN_HOST_ACC_INLINE constexpr void mp_for_each_inline_impl(L<T...>, F&& f)
        {
            using A = int[sizeof...(T)];
            (void) A{((void) f(T{}), 0)...};
        }
 
        template<typename FromList, template<auto...> class ToList>
        struct mp_unwrap_values_into_impl;
 
        template<template<class...> class FromList, typename... Values, template<auto...> class ToList>
        struct mp_unwrap_values_into_impl<FromList<Values...>, ToList>
        {
            using type = ToList<Values::value...>;
        };
 
        template<typename FromList, template<auto...> class ToList>
        using mp_unwrap_values_into = typename mp_unwrap_values_into_impl<FromList, ToList>::type;
 
        template<typename E, typename... Args>
        struct ReplacePlaceholdersImpl
        {
            using type = E;
        };
        template<std::size_t I, typename... Args>
        struct ReplacePlaceholdersImpl<mp_arg<I>, Args...>
        {
            using type = mp_at_c<mp_list<Args...>, I>;
        };
 
        template<template<typename...> typename E, typename... Ts, typename... Args>
        struct ReplacePlaceholdersImpl<E<Ts...>, Args...>
        {
            using type = E<typename ReplacePlaceholdersImpl<Ts, Args...>::type...>;
        };
    } // namespace internal
 
    template<typename L, typename F>
    // NOLINTNEXTLINE(readability-identifier-naming)
    LLAMA_FN_HOST_ACC_INLINE constexpr void mp_for_each_inline(F&& f)
    {
        internal::mp_for_each_inline_impl(mp_rename<L, mp_list>{}, std::forward<F>(f));
    }
 
    LLAMA_EXPORT
    template<typename Expression, typename... Args>
    using ReplacePlaceholders = typename internal::ReplacePlaceholdersImpl<Expression, Args...>::type;
} // namespace llama