mirror of
https://github.com/RGBCube/serenity
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70f49d0696
Return whether the time zone is in DST during the provided time from TimeZone::get_time_zone_offset,
86 lines
2.3 KiB
C++
86 lines
2.3 KiB
C++
/*
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* Copyright (c) 2022, Tim Flynn <trflynn89@pm.me>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibTimeZone/TimeZone.h>
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#include <time.h>
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namespace TimeZone {
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// NOTE: Without ENABLE_TIME_ZONE_DATA LibTimeZone operates in a UTC-only mode and only recognizes
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// the 'UTC' time zone, which is slightly more useful than a bunch of dummy functions that
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// can't do anything. When we build with time zone data, these weakly linked functions are
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// replaced with their proper counterparts.
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#if !ENABLE_TIME_ZONE_DATA
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enum class TimeZone : u16 {
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UTC,
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};
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#endif
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StringView current_time_zone()
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{
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static bool initialized_time_zone = false;
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if (!initialized_time_zone) {
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initialized_time_zone = true;
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tzset();
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}
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return canonicalize_time_zone(tzname[0]).value_or("UTC"sv);
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}
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Optional<TimeZone> __attribute__((weak)) time_zone_from_string([[maybe_unused]] StringView time_zone)
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{
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#if !ENABLE_TIME_ZONE_DATA
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if (time_zone.equals_ignoring_case("UTC"sv))
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return TimeZone::UTC;
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#endif
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return {};
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}
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StringView __attribute__((weak)) time_zone_to_string([[maybe_unused]] TimeZone time_zone)
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{
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#if !ENABLE_TIME_ZONE_DATA
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VERIFY(time_zone == TimeZone::UTC);
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return "UTC"sv;
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#else
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return {};
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#endif
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}
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Optional<StringView> canonicalize_time_zone(StringView time_zone)
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{
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auto maybe_time_zone = time_zone_from_string(time_zone);
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if (!maybe_time_zone.has_value())
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return {};
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auto canonical_time_zone = time_zone_to_string(*maybe_time_zone);
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if (canonical_time_zone.is_one_of("Etc/UTC"sv, "Etc/GMT"sv))
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return "UTC"sv;
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return canonical_time_zone;
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}
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Optional<DaylightSavingsRule> __attribute__((weak)) daylight_savings_rule_from_string(StringView) { return {}; }
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StringView __attribute__((weak)) daylight_savings_rule_to_string(DaylightSavingsRule) { return {}; }
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Optional<Offset> __attribute__((weak)) get_time_zone_offset([[maybe_unused]] TimeZone time_zone, AK::Time)
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{
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#if !ENABLE_TIME_ZONE_DATA
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VERIFY(time_zone == TimeZone::UTC);
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return Offset {};
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#else
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return {};
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#endif
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}
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Optional<Offset> get_time_zone_offset(StringView time_zone, AK::Time time)
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{
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if (auto maybe_time_zone = time_zone_from_string(time_zone); maybe_time_zone.has_value())
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return get_time_zone_offset(*maybe_time_zone, time);
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return {};
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}
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}
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