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https://github.com/LadybirdBrowser/ladybird.git
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LibTimeZone: Begin generating GMT offset rules for each time zone
This is a rather naive implementation, but serves as a first pass at determining the GMT offset for a time zone at a particular point in time. This implementation ignores DST (because we are not parsing any RULE entries yet), and ignores any offset patterns of the form "Mon>4" or "lastSun".
This commit is contained in:
Timothy Flynn
Linus Groh
parent
e9c42d0bc5
commit
09c0324880
Notes:
sideshowbarker
2024-07-17 21:13:15 +09:00
Author: https://github.com/trflynn89 Commit: https://github.com/SerenityOS/serenity/commit/09c0324880f Pull-request: https://github.com/SerenityOS/serenity/pull/11799 Reviewed-by: https://github.com/linusg ✅
4 changed files with 199 additions and 34 deletions
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@ -5,6 +5,7 @@
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*/
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#include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
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#include <AK/Format.h>
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#include <AK/HashMap.h>
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#include <AK/SourceGenerator.h>
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#include <AK/String.h>
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@ -15,45 +16,61 @@
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namespace {
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struct Time {
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i8 hour { 0 };
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u8 minute { 0 };
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u8 second { 0 };
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};
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struct DateTime {
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u16 year { 0 };
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Optional<u8> month;
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Optional<u8> day;
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Optional<u8> last_weekday;
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Optional<u8> after_weekday;
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Optional<u8> day;
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Optional<Time> time;
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Optional<u8> hour;
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Optional<u8> minute;
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Optional<u8> second;
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};
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struct TimeZone {
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Time offset;
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struct TimeZoneOffset {
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i64 offset { 0 };
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Optional<DateTime> until;
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};
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struct TimeZoneData {
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HashMap<String, Vector<TimeZone>> time_zones;
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HashMap<String, Vector<TimeZoneOffset>> time_zones;
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Vector<String> time_zone_names;
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Vector<Alias> time_zone_aliases;
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};
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static Time parse_time(StringView segment)
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{
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// FIXME: Some times end with a letter, e.g. "2:00u" and "2:00s". Figure out what this means and handle it.
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auto segments = segment.split_view(':');
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Time time {};
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time.hour = segments[0].to_int().value();
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time.minute = segments.size() > 1 ? segments[1].substring_view(0, 2).to_uint().value() : 0;
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time.second = segments.size() > 2 ? segments[2].substring_view(0, 2).to_uint().value() : 0;
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return time;
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}
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template<>
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struct AK::Formatter<DateTime> : Formatter<FormatString> {
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ErrorOr<void> format(FormatBuilder& builder, DateTime const& date_time)
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{
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return Formatter<FormatString>::format(builder,
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"{{ {}, {}, {}, {}, {}, {}, {}, {} }}",
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date_time.year,
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date_time.month.value_or(1),
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date_time.day.value_or(1),
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date_time.last_weekday.value_or(0),
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date_time.after_weekday.value_or(0),
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date_time.hour.value_or(0),
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date_time.minute.value_or(0),
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date_time.second.value_or(0));
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}
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};
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template<>
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struct AK::Formatter<TimeZoneOffset> : Formatter<FormatString> {
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ErrorOr<void> format(FormatBuilder& builder, TimeZoneOffset const& time_zone_offset)
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{
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return Formatter<FormatString>::format(builder,
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"{{ {}, {}, {} }}",
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time_zone_offset.offset,
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time_zone_offset.until.value_or({}),
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time_zone_offset.until.has_value());
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}
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};
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static Optional<DateTime> parse_date_time(Span<StringView const> segments)
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{
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constexpr auto months = Array { "Jan"sv, "Feb"sv, "Mar"sv, "Apr"sv, "May"sv, "Jun"sv, "Jul"sv, "Aug"sv, "Sep"sv, "Oct"sv, "Nov"sv, "Dec"sv };
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@ -69,7 +86,7 @@ static Optional<DateTime> parse_date_time(Span<StringView const> segments)
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date_time.year = segments[0].to_uint().value();
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if (segments.size() > 1)
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date_time.month = find_index(months.begin(), months.end(), segments[1]);
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date_time.month = find_index(months.begin(), months.end(), segments[1]) + 1;
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if (segments.size() > 2) {
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if (segments[2].starts_with("last"sv)) {
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@ -86,13 +103,31 @@ static Optional<DateTime> parse_date_time(Span<StringView const> segments)
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}
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}
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if (segments.size() > 3)
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date_time.time = parse_time(segments[3]);
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if (segments.size() > 3) {
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// FIXME: Some times end with a letter, e.g. "2:00u" and "2:00s". Figure out what this means and handle it.
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auto time_segments = segments[3].split_view(':');
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date_time.hour = time_segments[0].to_int().value();
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date_time.minute = time_segments.size() > 1 ? time_segments[1].substring_view(0, 2).to_uint().value() : 0;
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date_time.second = time_segments.size() > 2 ? time_segments[2].substring_view(0, 2).to_uint().value() : 0;
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}
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return date_time;
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}
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static Vector<TimeZone>& parse_zone(StringView zone_line, TimeZoneData& time_zone_data)
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static i64 parse_time_offset(StringView segment)
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{
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auto segments = segment.split_view(':');
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i64 hours = segments[0].to_int().value();
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i64 minutes = segments.size() > 1 ? segments[1].to_uint().value() : 0;
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i64 seconds = segments.size() > 2 ? segments[2].to_uint().value() : 0;
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i64 sign = ((hours < 0) || (segments[0] == "-0"sv)) ? -1 : 1;
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return (hours * 3600) + sign * ((minutes * 60) + seconds);
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}
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static Vector<TimeZoneOffset>& parse_zone(StringView zone_line, TimeZoneData& time_zone_data)
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{
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auto segments = zone_line.split_view_if([](char ch) { return (ch == '\t') || (ch == ' '); });
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@ -100,8 +135,8 @@ static Vector<TimeZone>& parse_zone(StringView zone_line, TimeZoneData& time_zon
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VERIFY(segments[0] == "Zone"sv);
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auto name = segments[1];
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TimeZone time_zone {};
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time_zone.offset = parse_time(segments[2]);
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TimeZoneOffset time_zone {};
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time_zone.offset = parse_time_offset(segments[2]);
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if (segments.size() > 5)
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time_zone.until = parse_date_time(segments.span().slice(5));
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@ -115,13 +150,13 @@ static Vector<TimeZone>& parse_zone(StringView zone_line, TimeZoneData& time_zon
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return time_zones;
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}
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static void parse_zone_continuation(StringView zone_line, Vector<TimeZone>& time_zones)
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static void parse_zone_continuation(StringView zone_line, Vector<TimeZoneOffset>& time_zones)
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{
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auto segments = zone_line.split_view_if([](char ch) { return (ch == '\t') || (ch == ' '); });
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// STDOFF RULES FORMAT [UNTIL]
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TimeZone time_zone {};
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time_zone.offset = parse_time(segments[0]);
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TimeZoneOffset time_zone {};
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time_zone.offset = parse_time_offset(segments[0]);
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if (segments.size() > 3)
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time_zone.until = parse_date_time(segments.span().slice(3));
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@ -145,7 +180,7 @@ static ErrorOr<void> parse_time_zones(StringView time_zone_path, TimeZoneData& t
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{
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// For reference, the man page for `zic` has the best documentation of the TZDB file format.
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auto file = TRY(Core::File::open(time_zone_path, Core::OpenMode::ReadOnly));
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Vector<TimeZone>* last_parsed_zone = nullptr;
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Vector<TimeZoneOffset>* last_parsed_zone = nullptr;
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while (file->can_read_line()) {
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auto line = file->read_line();
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@ -224,13 +259,72 @@ static void generate_time_zone_data_implementation(Core::File& file, TimeZoneDat
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#include <AK/Array.h>
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#include <AK/BinarySearch.h>
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#include <AK/Optional.h>
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#include <AK/Span.h>
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#include <AK/StringView.h>
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#include <AK/Time.h>
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#include <LibTimeZone/TimeZone.h>
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#include <LibTimeZone/TimeZoneData.h>
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namespace TimeZone {
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static constexpr auto seconds_per_day = 86'400;
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static constexpr auto seconds_per_hour = 3'600;
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static constexpr auto seconds_per_minute = 60;
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struct DateTime {
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AK::Time time_since_epoch() const
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{
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// FIXME: This implementation does not take last_weekday or after_weekday into account.
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i64 seconds_since_epoch = AK::days_since_epoch(year, month, day);
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seconds_since_epoch *= seconds_per_day;
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seconds_since_epoch += hour * seconds_per_hour;
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seconds_since_epoch += minute * seconds_per_minute;
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seconds_since_epoch += second;
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return AK::Time::from_seconds(seconds_since_epoch);
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}
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u16 year { 0 };
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u8 month { 1 };
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u8 day { 1 };
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u8 last_weekday { 0 };
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u8 after_weekday { 0 };
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u8 hour { 0 };
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u8 minute { 0 };
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u8 second { 0 };
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};
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struct TimeZoneOffset {
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i64 offset { 0 };
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DateTime until {};
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bool has_until { false };
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};
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)~~~");
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auto append_time_zone_offsets = [&](auto const& name, auto const& time_zone_offsets) {
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generator.set("name", name);
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generator.set("size", String::number(time_zone_offsets.size()));
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generator.append(R"~~~(
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static constexpr Array<TimeZoneOffset, @size@> @name@ { {
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)~~~");
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for (auto const& time_zone_offset : time_zone_offsets)
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generator.append(String::formatted(" {},\n", time_zone_offset));
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generator.append("} };\n");
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};
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generate_mapping(generator, time_zone_data.time_zone_names, "TimeZoneOffset"sv, "s_time_zone_offsets"sv, "s_time_zone_offsets_{}", format_identifier,
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[&](auto const& name, auto const& value) {
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auto const& time_zone_offsets = time_zone_data.time_zones.find(value)->value;
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append_time_zone_offsets(name, time_zone_offsets);
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});
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auto append_string_conversions = [&](StringView enum_title, StringView enum_snake, auto const& values, auto const& aliases) {
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HashValueMap<String> hashes;
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hashes.ensure_capacity(values.size());
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append_string_conversions("TimeZone"sv, "time_zone"sv, time_zone_data.time_zone_names, time_zone_data.time_zone_aliases);
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generator.append(R"~~~(
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Optional<i64> get_time_zone_offset(TimeZone time_zone, AK::Time time)
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{
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// FIXME: This implementation completely ignores DST.
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auto const& time_zone_offsets = s_time_zone_offsets[to_underlying(time_zone)];
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size_t index = 0;
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for (; index < time_zone_offsets.size(); ++index) {
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auto const& time_zone_offset = time_zone_offsets[index];
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if (!time_zone_offset.has_until || (time_zone_offset.until.time_since_epoch() > time))
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break;
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}
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VERIFY(index < time_zone_offsets.size());
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return time_zone_offsets[index].offset;
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}
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}
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)~~~");
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VERIFY(file.write(generator.as_string_view()));
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}
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}
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ErrorOr<int> serenity_main(Main::Arguments arguments)
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{
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StringView generated_header_path;
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@ -7,6 +7,7 @@
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#include <LibTest/TestCase.h>
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#include <AK/StringView.h>
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#include <AK/Time.h>
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#include <LibTimeZone/TimeZone.h>
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#if ENABLE_TIME_ZONE_DATA
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@ -84,4 +85,45 @@ TEST_CASE(canonicalize_time_zone)
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EXPECT(!TimeZone::canonicalize_time_zone("I don't exist"sv).has_value());
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}
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TEST_CASE(get_time_zone_offset)
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{
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auto offset = [](i64 sign, i64 hours, i64 minutes, i64 seconds) {
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return sign * ((hours * 3600) + (minutes * 60) + seconds);
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};
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auto test_offset = [](auto time_zone, i64 time, i64 expected_offset) {
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auto actual_offset = TimeZone::get_time_zone_offset(time_zone, AK::Time::from_seconds(time));
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VERIFY(actual_offset.has_value());
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EXPECT_EQ(*actual_offset, expected_offset);
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};
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test_offset("America/Chicago"sv, -2717668237, offset(-1, 5, 50, 36)); // Sunday, November 18, 1883 12:09:23 PM
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test_offset("America/Chicago"sv, -2717668236, offset(-1, 6, 00, 00)); // Sunday, November 18, 1883 12:09:24 PM
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test_offset("America/Chicago"sv, -1067810460, offset(-1, 6, 00, 00)); // Sunday, March 1, 1936 1:59:00 AM
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test_offset("America/Chicago"sv, -1067810400, offset(-1, 5, 00, 00)); // Sunday, March 1, 1936 2:00:00 AM
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test_offset("America/Chicago"sv, -1045432860, offset(-1, 5, 00, 00)); // Sunday, November 15, 1936 1:59:00 AM
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test_offset("America/Chicago"sv, -1045432800, offset(-1, 6, 00, 00)); // Sunday, November 15, 1936 2:00:00 AM
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test_offset("Europe/London"sv, -3852662401, offset(-1, 0, 01, 15)); // Tuesday, November 30, 1847 11:59:59 PM
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test_offset("Europe/London"sv, -3852662400, offset(+1, 0, 00, 00)); // Wednesday, December 1, 1847 12:00:00 AM
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test_offset("Europe/London"sv, -37238401, offset(+1, 0, 00, 00)); // Saturday, October 26, 1968 11:59:59 PM
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test_offset("Europe/London"sv, -37238400, offset(+1, 1, 00, 00)); // Sunday, October 27, 1968 12:00:00 AM
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test_offset("Europe/London"sv, 57722399, offset(+1, 1, 00, 00)); // Sunday, October 31, 1971 1:59:59 AM
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test_offset("Europe/London"sv, 57722400, offset(+1, 0, 00, 00)); // Sunday, October 31, 1971 2:00:00 AM
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test_offset("UTC"sv, -1641846268, offset(+1, 0, 00, 00));
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test_offset("UTC"sv, 0, offset(+1, 0, 00, 00));
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test_offset("UTC"sv, 1641846268, offset(+1, 0, 00, 00));
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test_offset("Etc/GMT+4"sv, -1641846268, offset(-1, 4, 00, 00));
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test_offset("Etc/GMT+5"sv, 0, offset(-1, 5, 00, 00));
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test_offset("Etc/GMT+6"sv, 1641846268, offset(-1, 6, 00, 00));
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test_offset("Etc/GMT-12"sv, -1641846268, offset(+1, 12, 00, 00));
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test_offset("Etc/GMT-13"sv, 0, offset(+1, 13, 00, 00));
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test_offset("Etc/GMT-14"sv, 1641846268, offset(+1, 14, 00, 00));
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EXPECT(!TimeZone::get_time_zone_offset("I don't exist"sv, {}).has_value());
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}
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#endif
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@ -24,4 +24,13 @@ Optional<StringView> canonicalize_time_zone(StringView time_zone)
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return canonical_time_zone;
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}
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Optional<i64> __attribute__((weak)) get_time_zone_offset(TimeZone, AK::Time) { return {}; }
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Optional<i64> 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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@ -8,6 +8,8 @@
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#include <AK/Optional.h>
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#include <AK/StringView.h>
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#include <AK/Time.h>
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#include <AK/Types.h>
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#include <LibTimeZone/Forward.h>
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namespace TimeZone {
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@ -16,4 +18,7 @@ Optional<TimeZone> time_zone_from_string(StringView time_zone);
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StringView time_zone_to_string(TimeZone time_zone);
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Optional<StringView> canonicalize_time_zone(StringView time_zone);
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Optional<i64> get_time_zone_offset(TimeZone time_zone, AK::Time time);
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Optional<i64> get_time_zone_offset(StringView time_zone, AK::Time time);
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}
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