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serenity/Userland/Libraries/LibTimeZone/TimeZone.cpp
Linus Groh 205d63c3f0 LibTimeZone: Operate in UTC-only mode when !ENABLE_TIME_ZONE_DATA
Instead of only having dummy functions that don't work with any input,
let's at least support one time zone: 'UTC'. This matches the basic
Temporal implementation for engines without ECMA-262, for example.
2022-01-11 22:17:39 +01:00

71 lines
1.8 KiB
C++

/*
* Copyright (c) 2022, Tim Flynn <trflynn89@pm.me>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibTimeZone/TimeZone.h>
namespace TimeZone {
// NOTE: Without ENABLE_TIME_ZONE_DATA LibTimeZone operates in a UTC-only mode and only recognizes
// the 'UTC' time zone, which is slightly more useful than a bunch of dummy functions that
// can't do anything. When we build with time zone data, these weakly linked functions are
// replaced with their proper counterparts.
#if !ENABLE_TIME_ZONE_DATA
enum class TimeZone : u16 {
UTC,
};
#endif
Optional<TimeZone> __attribute__((weak)) time_zone_from_string([[maybe_unused]] StringView time_zone)
{
#if !ENABLE_TIME_ZONE_DATA
if (time_zone.equals_ignoring_case("UTC"sv))
return TimeZone::UTC;
#endif
return {};
}
StringView __attribute__((weak)) time_zone_to_string([[maybe_unused]] TimeZone time_zone)
{
#if !ENABLE_TIME_ZONE_DATA
VERIFY(time_zone == TimeZone::UTC);
return "UTC"sv;
#else
return {};
#endif
}
Optional<StringView> canonicalize_time_zone(StringView time_zone)
{
auto maybe_time_zone = time_zone_from_string(time_zone);
if (!maybe_time_zone.has_value())
return {};
auto canonical_time_zone = time_zone_to_string(*maybe_time_zone);
if (canonical_time_zone.is_one_of("Etc/UTC"sv, "Etc/GMT"sv))
return "UTC"sv;
return canonical_time_zone;
}
Optional<i64> __attribute__((weak)) get_time_zone_offset([[maybe_unused]] TimeZone time_zone, AK::Time)
{
#if !ENABLE_TIME_ZONE_DATA
VERIFY(time_zone == TimeZone::UTC);
return 0;
#else
return {};
#endif
}
Optional<i64> get_time_zone_offset(StringView time_zone, AK::Time time)
{
if (auto maybe_time_zone = time_zone_from_string(time_zone); maybe_time_zone.has_value())
return get_time_zone_offset(*maybe_time_zone, time);
return {};
}
}