TypeManagement_NuCpp

A first idea of how i will manage type creation and type usage in my Nu language (that will be translated in cpp)

How to use it ?

Every type we want to record must respect the concept NuType_t (define in NuType.h). The best way to do it is to specify the template structure: NuType<StringLiteral>. Then we shall specify the template structure: cpp_type_info<type T> to make a link between RValue of C++ and the type for Nu.

Let's see an example:

#include "NuType.h"

template <>
struct NuType<"Complex"> : nutype_address {
    struct Complex {
        float re, im;
    };
    using t = Complex;
    inline static constexpr auto Name = "Complex";

    inline static constexpr size_t ID = 42;
    inline static constexpr auto IsBuiltin = false;

    constexpr Complex operator() (float&& re = 0, float&& im = 0) const {
        return Complex{re, im};
    }
    
    constexpr bool operator == (const NuType<"Complex">& t) const {
        return &t == this;
    }
    constexpr bool operator == (const nutype_address* t) const {
        return t == this;
    }

    static const NuType<"Complex">& Self;

    inline static constexpr const typeinfo_getter_of<NuType<"Complex">> TypeVal = {};
};
constexpr const NuType<"Complex"> Complex = NuType<"Complex">();
const NuType<"Complex">& NuType<"Complex">::Self = Complex;
template <>
struct cpp_type_info<NuType<"Complex">::t> {
    using NuTypeRef = NuType<"Complex">;
    inline static constexpr auto& NuTypeVal = Complex;
};

As you can see we created a constexpr value of the NuType<"Complex"> named Complex. It will the reference to create a Complex, it should be the only value of NuType<"Complex">. Then we specify the cpp_type_info<NuType<"Complex">::t> to make the link between the Complex's value and the the NuType<"Complex"> (So a link between the value and its type).

After defining your type you can start using var (define in Var.h) and Typeof/TypeofExpr functions/macro (define in Typeof.h). It is also recommanded to create an alias of the NuType you just created.

Let's see an example. We assume we've made all include and we use the code define above.

template <StringLiteral type_name>
using type = NuType<type_name>::t;

#define Typeof_t(expr) std::just_t<decltype(TypeofExpr(expr))>

int main() {
    var a = Complex(); // ok !!
    var<Typeof_t(a)> b; // ok !!
    if constexpr (Typeof(a) == Complex) {
        // ok !!
    }
    var<Complex_t> c;
}