better example

include/sp/protocol/Templates.h

@@ -0,0 +1,86 @@
+#pragma once
+
+#include <cstdint>
+
+namespace sp {
+
+/// @brief Default case, see field_index specialization for implementation details
+template <size_t N, typename T, template <size_t, typename> typename U, typename = void>
+static constexpr size_t field_index = 0;
+
+/// @brief A templated size_t that counts the number of existing classes U with a "field_name" member
+/// @tparam N Current counter for recursion (user should always call it with 0)
+/// @tparam T Can be any type, must be different for each field we want to be counted later (used because we can't have a empty
+/// template<> specialization nested in a class)
+/// @tparam U The templated class that will be searched for match
+template <size_t N, typename T, template <size_t, typename> typename U>
+static constexpr size_t field_index<N, T, U, std::void_t<decltype(U<N, T>::field_name)>> = 1 + field_index<N + 1, T, U>;
+
+/// @brief Concat multiple tuples in one big tuple
+/// @tparam ...input_t Multiple std::tuple types to concat
+template <typename... input_t>
+using tuple_cat_t = decltype(std::tuple_cat(std::declval<input_t>()...));
+
+template <typename T, typename Tuple>
+constexpr bool tuple_contains_type = false;
+template <typename T, typename... Ts>
+constexpr bool tuple_contains_type<T, std::tuple<Ts...>> = std::disjunction_v<std::is_same<T, Ts>...>;
+
+template <typename T, typename Tuple>
+constexpr int get_tuple_index = 0;
+template <typename T, typename... Rest>
+constexpr int get_tuple_index<T, std::tuple<T, Rest...>> = 0;
+template <typename T, typename First, typename... Rest>
+constexpr int get_tuple_index<T, std::tuple<First, Rest...>> = 1 + get_tuple_index<T, std::tuple<Rest...>>;
+
+// Template black magic to loop at compile time
+template <std::size_t... indices, class LoopBody>
+void loop_impl(std::index_sequence<indices...>, LoopBody&& loop_body) {
+	(loop_body(std::integral_constant<std::size_t, indices>{}), ...);
+}
+
+template <std::size_t N, class LoopBody>
+void loop(LoopBody&& loop_body) {
+	loop_impl(std::make_index_sequence<N>{}, std::forward<LoopBody>(loop_body));
+}
+
+namespace details {
+template <std::size_t TRem>
+class TupleForEachHelper {
+  public:
+	template <typename TTuple, typename TFunc>
+	static void exec(TTuple&& tuple, TFunc&& func) {
+		using Tuple = typename std::decay<TTuple>::type;
+		static const std::size_t TupleSize = std::tuple_size<Tuple>::value;
+		static_assert(TRem <= TupleSize, "Incorrect parameters");
+
+		// Invoke function with current element
+		static const std::size_t Idx = TupleSize - TRem;
+		func(std::get<Idx>(std::forward<TTuple>(tuple)));
+
+		// Compile time recursion - invoke function with the remaining elements
+		TupleForEachHelper<TRem - 1>::exec(std::forward<TTuple>(tuple), std::forward<TFunc>(func));
+	}
+};
+
+template <>
+class TupleForEachHelper<0> {
+  public:
+	// Stop compile time recursion
+	template <typename TTuple, typename TFunc>
+	static void exec(TTuple&& tuple, TFunc&& func) {
+		static_cast<void>(tuple);
+		static_cast<void>(func);
+	}
+};
+}  // namespace details
+
+template <typename TTuple, typename TFunc>
+void tupleForEach(TTuple&& tuple, TFunc&& func) {
+	using Tuple = typename std::decay<TTuple>::type;
+	static const std::size_t TupleSize = std::tuple_size<Tuple>::value;
+
+	details::TupleForEachHelper<TupleSize>::exec(std::forward<TTuple>(tuple), std::forward<TFunc>(func));
+}
+
+}  // namespace sp