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Add precision modifier for seconds in chrono format #3148
Add precision modifier for seconds in chrono format #3148
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Could you copy the summary (updating it if needed) from #3122? |
include/fmt/chrono.h
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return; | ||
} | ||
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FMT_ASSERT(std::is_floating_point<typename Duration::rep>::value, ""); |
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Let's add an alias for typename Duration::rep
and use it here and in several places below.
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Done
include/fmt/chrono.h
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@@ -1056,31 +1056,91 @@ void write_fractional_seconds(OutputIt& out, Duration d) { | |||
} | |||
} | |||
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template <typename Char, typename OutputIt, typename Duration> | |||
void write_fractional_seconds(OutputIt& out, Duration d, int precision) { |
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Let's merge this overload with the one above to reduce code duplication.
include/fmt/chrono.h
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: std::chrono::duration_cast<subsecond_precision>(fractional) | ||
.count(); | ||
uint32_or_64_or_128_t<long long> n = | ||
to_unsigned(to_nonnegative_int(subseconds, max_value<long long>())); |
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Can subseconds be negative?
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It's nonnegative because fractional
is nonnegative:
const auto fractional = detail::abs(d) - std::chrono::duration_cast<std::chrono::seconds>(d);
But subseconds can be signed or unsigned and to_unsigned
raises error if argument is unsigned, so i'll make static_cast
.
include/fmt/chrono.h
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// Format subseconds which are given as a floating point type with an appropiate | ||
// number of digits. We cannot pass the Duration here, as we explicitly need to | ||
// pass the Rep value in the chrono_formatter. | ||
template <typename Duration> | ||
void write_floating_seconds(memory_buffer& buf, Duration duration) { | ||
FMT_ASSERT(std::is_floating_point<typename Duration::rep>::value, ""); | ||
using Rep = typename Duration::rep; |
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nit: Rep -> rep to follow naming conventions
include/fmt/chrono.h
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void write_floating_seconds(memory_buffer& buf, Duration duration, | ||
int precision) { |
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Similarly, let's merge the two write_floating_seconds
overloads.
include/fmt/chrono.h
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bool is_floating_point = false; | ||
bool has_precision = false; |
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We only need one flag for the condition has_precision && !is_floating_point
, something like has_precision_integral
.
include/fmt/chrono.h
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const auto fractional = | ||
detail::abs(d) - std::chrono::duration_cast<std::chrono::seconds>(d); | ||
const auto& subseconds = |
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nit: &
is not needed here
include/fmt/chrono.h
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if (precision >= 0) { | ||
write_fractional_seconds<char_type>( | ||
out, std::chrono::duration<rep, Period>(val), precision); | ||
} else { | ||
write_fractional_seconds<char_type>( | ||
out, std::chrono::duration<rep, Period>(val)); | ||
} |
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Now that write_fractional_seconds
overloads have been merged, the if statement is no longer needed. You can just call
write_fractional_seconds<char_type>(
out, std::chrono::duration<rep, Period>(val), precision);
Thanks! |
Continuation of #3122
Add precision modifier for seconds in chrono format and test for it.
It's became important for custom datetime types that store date, time and subseconds. I want to use chrono format for those types, but I have no way to control subsecond precision.
Use case:
So precision can be applied not only for %Q spec, but for %S too.