tmdesc

Serialisation-oriented type members description library for c++ 14.

Work in progress. Probably abandoned..

Goals

• iteration by structure data members
• custom optional flags for the type or any data members of the type
• fast compilation
• completely constexpr
• с++ 14 support

Supported Compilers

Currently tested on gcc 10 and msvc 2017.

Earlier versions were compiled using gcc 6.2 and clang 6.0, but incompatibility issues could appear at the moment. These issues will be fixed later.

Example(currently works):

#include <iostream>
#include <tmdesc/algorithm/for_each.hpp>
#include <tmdesc/members_view.hpp>
#include <tmdesc/type_description.hpp>

// Custom member flag tag
struct additional_description_tag;

// Custom member flag implementation
constexpr tmdesc::flag<additional_description_tag, tmdesc::zstring_view>
additional_description(tmdesc::zstring_view descr) {
    return {descr};
}

namespace custom_ns {
struct Point {
    int x;
    int y;
};

// members description in free function template
template <class Impl>
constexpr auto tmdesc_info(::tmdesc::type_t<Point>, ::tmdesc::info_builder<Impl> wrap) {
    return wrap(wrap.member("x", &Point::x), //
                wrap.member("y", &Point::y));
}

struct Rect {
    Point top_left;
    Point bottom_right;

    // members description in friend function template
    template <class Impl>
    friend constexpr auto tmdesc_info(::tmdesc::type_t<Rect>, ::tmdesc::info_builder<Impl> wrap) {
        return wrap(wrap.member("tl", &Rect::top_left),
                    wrap.member("br", &Rect::bottom_right,
                                // custom flag for member
                                wrap.flags(additional_description("br point description"))));
    }
};
} // namespace custom_ns

void print(int v) { std::cout << v; }
void print(tmdesc::zstring_view str) { std::cout << "\"" << str.c_str() << "\""; }

template <class T, std::enable_if_t<tmdesc::has_type_info_v<T>, bool> = true>
void print(const T& object_with_description) {
    std::cout << "{ ";
    tmdesc::zstring_view separator = "";
    ::tmdesc::for_each(tmdesc::members_view(object_with_description), [&](auto member) {
        std::cout << separator.c_str() << member.name().c_str() << ": { ";

        // Using a custom flag if it exists
        auto&& descr = member.flags().find_flag(tmdesc::type_t<additional_description_tag>{});
        descr.if_some(
            [&](auto descr) { std::cout << "description: \"" << descr.c_str() << "\", "; });

        std::cout << "value: ";
        print(member.get()); // get reference to object member, const reference in this case
        std::cout << " }";

        separator = ", ";
    });
    std::cout << " }";
}

int main() {
    custom_ns::Rect rect{{42, 20}, {3, -11}};
    print(rect);
    std::cout << std::endl;
    return 0;
}

Output:

{ tl: { value: { x: { value: 42 }, y: { value: 20 } } }, br: { description: "br point description", value: { x: { value: 3 }, y: { value: -11 } } } }