forstio/source/kelgin/message_container.h

#pragma once

#include "schema.h"

namespace gin {
template <class T> class MessageContainer;

template <class T, class Container> class Message;

template <size_t N, class... T> struct MessageParameterPackType;

template <class TN, class... T> struct MessageParameterPackType<0, TN, T...> {
	using Type = T;
};

template <size_t N, class TN, class... T>
struct MessageParameterPackType<N, TN, T...> {
	using Type = typename MessageParameterPackType<N - 1, T...>::Type;
};

template <class T, class... TL> struct MessageParameterPackIndex;

template <class T, class... TL> struct MessageParameterPackIndex<T, T, TL...> {
	static constexpr size_t Value = 0u;
};

template <class T, class TL0, class... TL>
struct MessageParameterPackIndex<T, TL0, TL...> {
	static constexpr size_t Value =
		1u + MessageParameterPackIndex<T, TL...>::Value;
};

template <class... V, class... K>
class MessageContainer<schema::Struct<schema::NamedMember<V, K>...>> {
private:
	using ValueType = std::tuple<Message<V, MessageContainer<V>>...>;
	ValueType values;

public:
	using SchemaType = schema::Struct<schema::NamedMember<V, K>...>;

	template <size_t i>
	using Element =
		MessageParameterPackType<N, Message<V, MessageContainer<V>>...>;

	template <size_t i> Element<i> &get() { return std::get<i>(values); }
};
} // namespace gin