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Support formatting of std time_point with utc_clock (#3110)

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Patrick Roocks 2022-09-28 16:31:53 +02:00 committed by GitHub
parent 6e0a5f7fba
commit ad719619cc
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2 changed files with 39 additions and 0 deletions
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28
include/fmt/chrono.h
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@ -22,6 +22,15 @@
FMT_BEGIN_NAMESPACE FMT_BEGIN_NAMESPACE
// Check if std::chrono::utc_timestamp is available.
#ifndef FMT_USE_UTC_TIME
# ifdef __cpp_lib_chrono
# define FMT_USE_UTC_TIME (__cpp_lib_chrono >= 201907L)
# else
# define FMT_USE_UTC_TIME 0
# endif
#endif
// Enable tzset. // Enable tzset.
#ifndef FMT_USE_TZSET #ifndef FMT_USE_TZSET
// UWP doesn't provide _tzset. // UWP doesn't provide _tzset.
@ -2014,6 +2023,25 @@ struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
} }
}; };
#if FMT_USE_UTC_TIME
template <typename Char, typename Duration>
struct formatter<std::chrono::time_point<std::chrono::utc_clock, Duration>,
Char> : formatter<std::tm, Char> {
FMT_CONSTEXPR formatter() {
basic_string_view<Char> default_specs =
detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>{};
this->do_parse(default_specs.begin(), default_specs.end());
}
template <typename FormatContext>
auto format(std::chrono::time_point<std::chrono::utc_clock> val,
FormatContext& ctx) const -> decltype(ctx.out()) {
return formatter<std::tm, Char>::format(
localtime(std::chrono::utc_clock::to_sys(val)), ctx);
}
};
#endif
template <typename Char> struct formatter<std::tm, Char> { template <typename Char> struct formatter<std::tm, Char> {
private: private:
enum class spec { enum class spec {

11
test/chrono-test.cc
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@ -641,3 +641,14 @@ TEST(chrono_test, cpp20_duration_subsecond_support) {
} }
#endif // FMT_STATIC_THOUSANDS_SEPARATOR #endif // FMT_STATIC_THOUSANDS_SEPARATOR
// Disable the utc_clock test for windows, as the icu.dll used for tzdb
// (time zone database) is not shipped with many windows versions.
#if FMT_USE_UTC_TIME && !defined(_WIN32)
TEST(chrono_test, utc_clock) {
auto t1 = std::chrono::system_clock::now();
auto t1_utc = std::chrono::utc_clock::from_sys(t1);
EXPECT_EQ(fmt::format("{:%Y-%m-%d %H:%M:%S}", t1),
fmt::format("{:%Y-%m-%d %H:%M:%S}", t1_utc));
}
#endif