...

common/adc_traits.h

@@ -1,9 +1,9 @@
 #pragma once
 
+#include <format>
 #include <ranges>
 #include <tuple>
 #include <type_traits>
-#include <format>
 
 
 /*
@@ -17,16 +17,28 @@ namespace adc::traits
 {
 
 // check if type can be used with std::format_to
-// (from https://stackoverflow.com/questions/72430369/how-to-check-that-a-type-is-formattable-using-type-traits-concepts)
-template<typename T>
-concept formattable = requires (T& v, std::format_context ctx) {
-    std::formatter<std::remove_cvref_t<T>>().format(v, ctx);
-};
+// (from
+// https://stackoverflow.com/questions/72430369/how-to-check-that-a-type-is-formattable-using-type-traits-concepts)
+template <typename T>
+concept formattable =
+    requires(T& v, std::format_context ctx) { std::formatter<std::remove_cvref_t<T>>().format(v, ctx); };
 
 
 // range of char/const char
 template <typename R, typename CharT = char>
-concept adc_char_range = std::ranges::range<R> && std::is_same_v<std::remove_cv_t<std::ranges::range_value_t<R>>, CharT>;
+concept adc_char_range =
+    std::ranges::range<R> && std::is_same_v<std::remove_cv_t<std::ranges::range_value_t<R>>, CharT>;
+
+
+// output range of char/const char
+template <typename R, typename CharT = char>
+concept adc_output_char_range = std::ranges::output_range<R, CharT>;
+
+
+// range of char/const char
+template <typename R, typename CharT = char>
+concept adc_input_char_range = std::ranges::input_range<CharT>;
+
 
 // deduce returned type of callable
 template <typename T>