#include #include #include using day_t = std::chrono::duration>; template struct duration_traits {}; #define DURATION_TRAITS(Duration, Singular, Plural) \ template<> struct duration_traits { \ constexpr static const char* singular = Singular; \ constexpr static const char* plural = Plural; \ } DURATION_TRAITS(std::chrono::milliseconds, "millisecond", "milliseconds"); DURATION_TRAITS(std::chrono::seconds, "second", "seconds"); DURATION_TRAITS(std::chrono::minutes, "minute", "minutes"); DURATION_TRAITS(std::chrono::hours, "hour", "hours"); DURATION_TRAITS(day_t, "day", "days"); using divisions = std::tuple; namespace detail { template struct print_duration_impl_ {}; template struct print_duration_impl_ { template static bool print(std::ostream& os, Duration& dur) { const auto started_printing = print_duration_impl_::print(os, dur); const auto n = std::chrono::duration_cast(dur); const auto count = n.count(); if (count == 0) { return started_printing; } if (started_printing) { os << ' '; } using traits = duration_traits; os << count << ' ' << (count == 1 ? traits::singular : traits::plural); dur -= n; return true; } }; template<> struct print_duration_impl_<> { template static bool print(std::ostream& os, Duration& dur) { return false; } }; template struct print_duration {}; template struct print_duration> { template static void print(std::ostream& os, Duration dur) { print_duration_impl_::print(os, dur); } }; } template std::ostream& operator<<(std::ostream& os, const std::chrono::duration& dur) { detail::print_duration::print(os, dur); return os; } #include int main() { auto start = std::chrono::system_clock::now(); std::this_thread::sleep_for(std::chrono::milliseconds(1492)); auto end = std::chrono::system_clock::now(); std::cout << (end - start) << std::endl; return 0; }