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LibJS: Avoid js_string() allocation in parse_time_zone_offset_string()

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No need to take the spec literally here since we know the input values
are guaranteed to be integral numbers. Use AK string to number parsing
functionality instead and save a couple of PrimitiveString allocations.

This matches what we already do in parse_temporal_time_zone_string().
This commit is contained in:
Linus Groh 2022-01-12 20:28:22 +01:00
parent 392f5bfebd
commit cf6ceb956f
1 changed files with 11 additions and 8 deletions
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19
Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
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@ -297,20 +297,22 @@ ThrowCompletionOr<double> parse_time_zone_offset_string(GlobalObject& global_obj
}
// 7. Set hours to ! ToIntegerOrInfinity(hours).
auto hours = MUST(Value(js_string(vm, hours_part)).to_integer_or_infinity(global_object));
// 8. Set minutes to ! ToIntegerOrInfinity(minutes).
auto minutes = MUST(Value(js_string(vm, minutes_part.value_or(""sv))).to_integer_or_infinity(global_object));
// 9. Set seconds to ! ToIntegerOrInfinity(seconds).
auto seconds = MUST(Value(js_string(vm, seconds_part.value_or(""sv))).to_integer_or_infinity(global_object));
auto hours = *hours_part.to_uint<u8>();
double nanoseconds;
// 8. Set minutes to ! ToIntegerOrInfinity(minutes).
auto minutes = *minutes_part.value_or("0"sv).to_uint<u8>();
// 9. Set seconds to ! ToIntegerOrInfinity(seconds).
auto seconds = *seconds_part.value_or("0"sv).to_uint<u8>();
i32 nanoseconds;
// 10. If fraction is not undefined, then
if (fraction_part.has_value()) {
// a. Set fraction to the string-concatenation of the previous value of fraction and the string "000000000".
auto fraction = String::formatted("{}000000000", *fraction_part);
// b. Let nanoseconds be the String value equal to the substring of fraction consisting of the code units with indices 0 (inclusive) through 9 (exclusive).
// c. Set nanoseconds to ! ToIntegerOrInfinity(nanoseconds).
nanoseconds = MUST(Value(js_string(vm, fraction.substring_view(0, 9))).to_integer_or_infinity(global_object));
nanoseconds = *fraction.substring(0, 9).to_int<i32>();
}
// 11. Else,
else {
@ -318,7 +320,8 @@ ThrowCompletionOr<double> parse_time_zone_offset_string(GlobalObject& global_obj
nanoseconds = 0;
}
// 12. Return sign × (((hours × 60 + minutes) × 60 + seconds) × 10^9 + nanoseconds).
return sign * (((hours * 60 + minutes) * 60 + seconds) * 1000000000 + nanoseconds);
// NOTE: Decimal point in 10^9 is important, otherwise it's all integers and the result overflows!
return sign * (((hours * 60 + minutes) * 60 + seconds) * 1000000000.0 + nanoseconds);
}
// 11.6.9 FormatTimeZoneOffsetString ( offsetNanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-formattimezoneoffsetstring