Free function to functor adapter

free_function.hpp

// SPDX-License-Identifier: 0BSD
#pragma once

#include <type_traits>
#include <utility>

namespace detri
{
    template<class T>
    concept is_free_fn_ptr = std::is_pointer_v<T> && std::is_function_v<std::remove_pointer_t<T>>;

    template<auto Fn>
        requires is_free_fn_ptr<decltype(Fn)> && (Fn != nullptr)
    struct free_function
    {
        template<class... Args>
            requires requires(Args&&... args)
            {
                Fn(std::forward<Args>(args)...);
            }
        constexpr decltype(auto) operator()(Args&&... args) const
            noexcept(std::is_nothrow_invocable_v<decltype(Fn), Args...>)
        {
            return Fn(std::forward<Args>(args)...);
        }
    };
}