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Added support for subsecond resolution for time_point and %T or %S formats

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Filip Brcic 2021-05-18 14:45:34 +02:00
parent 0dd91e20d5
commit ac6dd9f6de
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GPG Key ID: 15FB92681DE569DA
1 changed files with 18 additions and 3 deletions
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21
include/fmt/chrono.h
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@ -412,7 +412,11 @@ struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
auto format(std::chrono::time_point<std::chrono::system_clock> val,
FormatContext& ctx) -> decltype(ctx.out()) {
std::tm time = localtime(val);
return formatter<std::tm, Char>::format(time, ctx);
auto epoch = val.time_since_epoch();
auto seconds = std::chrono::duration_cast<std::chrono::milliseconds>(epoch).count() / 1000;
auto today = std::chrono::high_resolution_clock::duration(std::chrono::milliseconds(seconds * 1000));
auto subseconds = std::chrono::duration_cast<std::chrono::nanoseconds>(epoch - today);
return formatter<std::tm, Char>::format(time, ctx, subseconds.count());
}
};
@ -428,14 +432,20 @@ template <typename Char> struct formatter<std::tm, Char> {
}
template <typename FormatContext>
auto format(const std::tm& tm, FormatContext& ctx) const
auto format(const std::tm& tm, FormatContext& ctx, int subseconds) const
-> decltype(ctx.out()) {
basic_memory_buffer<Char> tm_format;
tm_format.append(specs.begin(), specs.end());
// By appending an extra space we can distinguish an empty result that
// indicates insufficient buffer size from a guaranteed non-empty result
// https://github.com/fmtlib/fmt/issues/2238
tm_format.push_back(' ');
auto hasS = std::find(tm_format.begin(), tm_format.end(), 'S') != tm_format.end();
auto hasT = std::find(tm_format.begin(), tm_format.end(), 'T') != tm_format.end();
auto writeSubseconds = (hasS || hasT) && (subseconds != 0);
if (writeSubseconds)
tm_format.push_back('.');
else
tm_format.push_back(' ');
tm_format.push_back('\0');
basic_memory_buffer<Char> buf;
size_t start = buf.size();
@ -449,6 +459,11 @@ template <typename Char> struct formatter<std::tm, Char> {
const size_t MIN_GROWTH = 10;
buf.reserve(buf.capacity() + (size > MIN_GROWTH ? size : MIN_GROWTH));
}
if (writeSubseconds) {
buf.append(std::to_string(subseconds));
}
// Remove the extra space.
return std::copy(buf.begin(), buf.end() - 1, ctx.out());
}