Type Restrictor

---

by: Ksenia Milkand & Cxx

#include <iostream>
#include <type_traits>

template <class type, class... types>
struct list
{
    private:
        template <class>
        struct identity {
        };

        template <class... types_>
        struct identities : identity <types_>... {
        };

    public:
        template <class element, class... elements>
        struct contain
        {
            constexpr static bool value = std::is_base_of <identity <type> , identities <element, elements...>>::value || (std::is_base_of <identity <types>, identities <element, elements...>>::value || ...);
        };
};

template <class element_0, class... element_rest>
struct _restrict_
{
    template <class type_0, class... type_rest>
    struct _access_to_ {
    
    template <class type_x0, class... type_rest>
    constexpr static decltype(auto) process(type_x0 args0, type_rest... arg_rest)
    {
    
    return [](auto... args)
    {
    static_assert(!(list <type_x0, type_rest...>::template contain <element_0, element_rest...>::value &&
                    list <    decltype(args)...>::template contain <   type_0, type_rest   ...>::value),
    "bad_type_access" );

    puts("processing elements");
    };
    
    };
    
    };

    _restrict_() = delete;
};

int main() {
    using mode = _restrict_ <int>::_access_to_ <float, double>;
  //mode::process(int{})(float{}, double{}); // assert
    mode::process(char{})(float{}, double{});
    return 0;
}

1: Ksenia Milkand & Cxx - https://godbolt.org/z/IMU6KX

License

This project is licensed under the MIT License. See the LICENSE file for more details.