...

mcc/mcc_traits.h

@@ -7,6 +7,18 @@
 namespace mcc::traits
 {
 
+
+template <std::ranges::range R>
+static constexpr size_t mcc_range_size(const R& r)
+{
+    if constexpr (std::ranges::sized_range<R>) {
+        return r.size();
+    } else {
+        return std::ranges::distance(r.begin(), r.end());
+    }
+}
+
+
 template <typename R>
 concept mcc_char_view = std::ranges::view<R> && std::same_as<std::ranges::range_value_t<R>, char>;
 
@@ -59,6 +71,16 @@ concept mcc_systime_c = requires {
 };
 
 
+template <typename R>
+concept mcc_output_duration_range_c =
+    std::ranges::output_range<R, std::ranges::range_value_t<R>> && mcc_time_duration_c<std::ranges::range_value_t<R>>;
+// concept mcc_output_duration_range_c = std::ranges::range<R> && requires(R r) {
+//     []<class Rep, class Period>(std::type_identity<std::chrono::duration<Rep, Period>>) {
+
+//     }(std::ranges::range_value_t<R>());
+
+// };
+
 /*  a callable concept and its signature traits   */
 
 template <typename T>