| // Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| // part of "core_patch.dart"; |
| |
| // This file is identical to the VM `date_patch.dart` except for the |
| // implementation of `_getCurrentMicros` and the `_jsDateNow` import. |
| // TODO(askesc): Share this file with the VM when the patching mechanism gains |
| // support for patching an external member from a patch in a separate patch. |
| |
| @pragma("wasm:import", "Date.now") |
| external double _jsDateNow(); |
| |
| // VM implementation of DateTime. |
| @patch |
| class DateTime { |
| // Natives. |
| // The natives have been moved up here to work around Issue 10401. |
| @pragma("vm:external-name", "DateTime_currentTimeMicros") |
| static int _getCurrentMicros() => |
| (_jsDateNow() * Duration.microsecondsPerMillisecond).toInt(); |
| |
| @pragma("vm:external-name", "DateTime_timeZoneName") |
| external static String _timeZoneNameForClampedSeconds(int secondsSinceEpoch); |
| |
| @pragma("vm:external-name", "DateTime_timeZoneOffsetInSeconds") |
| external static int _timeZoneOffsetInSecondsForClampedSeconds( |
| int secondsSinceEpoch); |
| |
| static const _MICROSECOND_INDEX = 0; |
| static const _MILLISECOND_INDEX = 1; |
| static const _SECOND_INDEX = 2; |
| static const _MINUTE_INDEX = 3; |
| static const _HOUR_INDEX = 4; |
| static const _DAY_INDEX = 5; |
| static const _WEEKDAY_INDEX = 6; |
| static const _MONTH_INDEX = 7; |
| static const _YEAR_INDEX = 8; |
| |
| List<int>? __parts; |
| |
| @patch |
| DateTime.fromMillisecondsSinceEpoch(int millisecondsSinceEpoch, |
| {bool isUtc: false}) |
| : this._withValue( |
| _validateMilliseconds(millisecondsSinceEpoch) * |
| Duration.microsecondsPerMillisecond, |
| isUtc: isUtc); |
| |
| @patch |
| DateTime.fromMicrosecondsSinceEpoch(int microsecondsSinceEpoch, |
| {bool isUtc: false}) |
| : this._withValue(microsecondsSinceEpoch, isUtc: isUtc); |
| |
| @patch |
| DateTime._internal(int year, int month, int day, int hour, int minute, |
| int second, int millisecond, int microsecond, bool isUtc) |
| : this.isUtc = isUtc, |
| this._value = _brokenDownDateToValue(year, month, day, hour, minute, |
| second, millisecond, microsecond, isUtc) ?? |
| -1 { |
| if (_value == -1) throw new ArgumentError(); |
| if (isUtc == null) throw new ArgumentError(); |
| } |
| |
| static int _validateMilliseconds(int millisecondsSinceEpoch) => |
| RangeError.checkValueInInterval( |
| millisecondsSinceEpoch, |
| -_maxMillisecondsSinceEpoch, |
| _maxMillisecondsSinceEpoch, |
| "millisecondsSinceEpoch"); |
| |
| @patch |
| DateTime._now() |
| : isUtc = false, |
| _value = _getCurrentMicros(); |
| |
| @patch |
| String get timeZoneName { |
| if (isUtc) return "UTC"; |
| return _timeZoneName(microsecondsSinceEpoch); |
| } |
| |
| @patch |
| Duration get timeZoneOffset { |
| if (isUtc) return new Duration(); |
| int offsetInSeconds = _timeZoneOffsetInSeconds(microsecondsSinceEpoch); |
| return new Duration(seconds: offsetInSeconds); |
| } |
| |
| @patch |
| bool operator ==(dynamic other) => |
| other is DateTime && |
| _value == other.microsecondsSinceEpoch && |
| isUtc == other.isUtc; |
| |
| @patch |
| bool isBefore(DateTime other) => _value < other.microsecondsSinceEpoch; |
| |
| @patch |
| bool isAfter(DateTime other) => _value > other.microsecondsSinceEpoch; |
| |
| @patch |
| bool isAtSameMomentAs(DateTime other) => |
| _value == other.microsecondsSinceEpoch; |
| |
| @patch |
| int compareTo(DateTime other) => |
| _value.compareTo(other.microsecondsSinceEpoch); |
| |
| /** The first list contains the days until each month in non-leap years. The |
| * second list contains the days in leap years. */ |
| static const List<List<int>> _DAYS_UNTIL_MONTH = const [ |
| const [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334], |
| const [0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335] |
| ]; |
| |
| static List<int> _computeUpperPart(int localMicros) { |
| const int DAYS_IN_4_YEARS = 4 * 365 + 1; |
| const int DAYS_IN_100_YEARS = 25 * DAYS_IN_4_YEARS - 1; |
| const int DAYS_IN_400_YEARS = 4 * DAYS_IN_100_YEARS + 1; |
| const int DAYS_1970_TO_2000 = 30 * 365 + 7; |
| const int DAYS_OFFSET = |
| 1000 * DAYS_IN_400_YEARS + 5 * DAYS_IN_400_YEARS - DAYS_1970_TO_2000; |
| const int YEARS_OFFSET = 400000; |
| |
| int resultYear = 0; |
| int resultMonth = 0; |
| int resultDay = 0; |
| |
| // Always round down. |
| final int daysSince1970 = |
| _flooredDivision(localMicros, Duration.microsecondsPerDay); |
| int days = daysSince1970; |
| days += DAYS_OFFSET; |
| resultYear = 400 * (days ~/ DAYS_IN_400_YEARS) - YEARS_OFFSET; |
| days = unsafeCast<int>(days.remainder(DAYS_IN_400_YEARS)); |
| days--; |
| int yd1 = days ~/ DAYS_IN_100_YEARS; |
| days = unsafeCast<int>(days.remainder(DAYS_IN_100_YEARS)); |
| resultYear += 100 * yd1; |
| days++; |
| int yd2 = days ~/ DAYS_IN_4_YEARS; |
| days = unsafeCast<int>(days.remainder(DAYS_IN_4_YEARS)); |
| resultYear += 4 * yd2; |
| days--; |
| int yd3 = days ~/ 365; |
| days = unsafeCast<int>(days.remainder(365)); |
| resultYear += yd3; |
| |
| bool isLeap = (yd1 == 0 || yd2 != 0) && yd3 == 0; |
| if (isLeap) days++; |
| |
| List<int> daysUntilMonth = _DAYS_UNTIL_MONTH[isLeap ? 1 : 0]; |
| for (resultMonth = 12; |
| daysUntilMonth[resultMonth - 1] > days; |
| resultMonth--) { |
| // Do nothing. |
| } |
| resultDay = days - daysUntilMonth[resultMonth - 1] + 1; |
| |
| int resultMicrosecond = localMicros % Duration.microsecondsPerMillisecond; |
| int resultMillisecond = |
| _flooredDivision(localMicros, Duration.microsecondsPerMillisecond) % |
| Duration.millisecondsPerSecond; |
| int resultSecond = |
| _flooredDivision(localMicros, Duration.microsecondsPerSecond) % |
| Duration.secondsPerMinute; |
| |
| int resultMinute = |
| _flooredDivision(localMicros, Duration.microsecondsPerMinute); |
| resultMinute %= Duration.minutesPerHour; |
| |
| int resultHour = |
| _flooredDivision(localMicros, Duration.microsecondsPerHour); |
| resultHour %= Duration.hoursPerDay; |
| |
| // In accordance with ISO 8601 a week |
| // starts with Monday. Monday has the value 1 up to Sunday with 7. |
| // 1970-1-1 was a Thursday. |
| int resultWeekday = ((daysSince1970 + DateTime.thursday - DateTime.monday) % |
| DateTime.daysPerWeek) + |
| DateTime.monday; |
| |
| List<int> list = new List<int>.filled(_YEAR_INDEX + 1, 0); |
| list[_MICROSECOND_INDEX] = resultMicrosecond; |
| list[_MILLISECOND_INDEX] = resultMillisecond; |
| list[_SECOND_INDEX] = resultSecond; |
| list[_MINUTE_INDEX] = resultMinute; |
| list[_HOUR_INDEX] = resultHour; |
| list[_DAY_INDEX] = resultDay; |
| list[_WEEKDAY_INDEX] = resultWeekday; |
| list[_MONTH_INDEX] = resultMonth; |
| list[_YEAR_INDEX] = resultYear; |
| return list; |
| } |
| |
| List<int> get _parts { |
| return __parts ??= _computeUpperPart(_localDateInUtcMicros); |
| } |
| |
| @patch |
| DateTime add(Duration duration) { |
| return new DateTime._withValue(_value + duration.inMicroseconds, |
| isUtc: isUtc); |
| } |
| |
| @patch |
| DateTime subtract(Duration duration) { |
| return new DateTime._withValue(_value - duration.inMicroseconds, |
| isUtc: isUtc); |
| } |
| |
| @patch |
| Duration difference(DateTime other) { |
| return new Duration(microseconds: _value - other.microsecondsSinceEpoch); |
| } |
| |
| @patch |
| int get millisecondsSinceEpoch => |
| _value ~/ Duration.microsecondsPerMillisecond; |
| |
| @patch |
| int get microsecondsSinceEpoch => _value; |
| |
| @patch |
| int get microsecond => _parts[_MICROSECOND_INDEX]; |
| |
| @patch |
| int get millisecond => _parts[_MILLISECOND_INDEX]; |
| |
| @patch |
| int get second => _parts[_SECOND_INDEX]; |
| |
| @patch |
| int get minute => _parts[_MINUTE_INDEX]; |
| |
| @patch |
| int get hour => _parts[_HOUR_INDEX]; |
| |
| @patch |
| int get day => _parts[_DAY_INDEX]; |
| |
| @patch |
| int get weekday => _parts[_WEEKDAY_INDEX]; |
| |
| @patch |
| int get month => _parts[_MONTH_INDEX]; |
| |
| @patch |
| int get year => _parts[_YEAR_INDEX]; |
| |
| /** |
| * Returns the amount of microseconds in UTC that represent the same values |
| * as [this]. |
| * |
| * Say `t` is the result of this function, then |
| * * `this.year == new DateTime.fromMicrosecondsSinceEpoch(t, true).year`, |
| * * `this.month == new DateTime.fromMicrosecondsSinceEpoch(t, true).month`, |
| * * `this.day == new DateTime.fromMicrosecondsSinceEpoch(t, true).day`, |
| * * `this.hour == new DateTime.fromMicrosecondsSinceEpoch(t, true).hour`, |
| * * ... |
| * |
| * Daylight savings is computed as if the date was computed in [1970..2037]. |
| * If [this] lies outside this range then it is a year with similar |
| * properties (leap year, weekdays) is used instead. |
| */ |
| int get _localDateInUtcMicros { |
| int micros = _value; |
| if (isUtc) return micros; |
| int offset = |
| _timeZoneOffsetInSeconds(micros) * Duration.microsecondsPerSecond; |
| return micros + offset; |
| } |
| |
| static int _flooredDivision(int a, int b) { |
| return (a - (a < 0 ? b - 1 : 0)) ~/ b; |
| } |
| |
| // Returns the days since 1970 for the start of the given [year]. |
| // [year] may be before epoch. |
| static int _dayFromYear(int year) { |
| return 365 * (year - 1970) + |
| _flooredDivision(year - 1969, 4) - |
| _flooredDivision(year - 1901, 100) + |
| _flooredDivision(year - 1601, 400); |
| } |
| |
| static bool _isLeapYear(int y) { |
| // (y % 16 == 0) matches multiples of 400, and is faster than % 400. |
| return (y % 4 == 0) && ((y % 16 == 0) || (y % 100 != 0)); |
| } |
| |
| /// Converts the given broken down date to microseconds. |
| @patch |
| static int? _brokenDownDateToValue(int year, int month, int day, int hour, |
| int minute, int second, int millisecond, int microsecond, bool isUtc) { |
| // Simplify calculations by working with zero-based month. |
| --month; |
| // Deal with under and overflow. |
| if (month >= 12) { |
| year += month ~/ 12; |
| month = month % 12; |
| } else if (month < 0) { |
| int realMonth = month % 12; |
| year += (month - realMonth) ~/ 12; |
| month = realMonth; |
| } |
| |
| // First compute the seconds in UTC, independent of the [isUtc] flag. If |
| // necessary we will add the time-zone offset later on. |
| int days = day - 1; |
| days += _DAYS_UNTIL_MONTH[_isLeapYear(year) ? 1 : 0][month]; |
| days += _dayFromYear(year); |
| int microsecondsSinceEpoch = days * Duration.microsecondsPerDay + |
| hour * Duration.microsecondsPerHour + |
| minute * Duration.microsecondsPerMinute + |
| second * Duration.microsecondsPerSecond + |
| millisecond * Duration.microsecondsPerMillisecond + |
| microsecond; |
| |
| if (!isUtc) { |
| // Since [_timeZoneOffsetInSeconds] will crash if the input is far out of |
| // the valid range we do a preliminary test that weeds out values that can |
| // not become valid even with timezone adjustments. |
| // The timezone adjustment is always less than a day, so adding a security |
| // margin of one day should be enough. |
| if (microsecondsSinceEpoch.abs() > |
| _maxMillisecondsSinceEpoch * Duration.microsecondsPerMillisecond + |
| Duration.microsecondsPerDay) { |
| return null; |
| } |
| |
| microsecondsSinceEpoch -= _toLocalTimeOffset(microsecondsSinceEpoch); |
| } |
| if (microsecondsSinceEpoch.abs() > |
| _maxMillisecondsSinceEpoch * Duration.microsecondsPerMillisecond) { |
| return null; |
| } |
| return microsecondsSinceEpoch; |
| } |
| |
| static int _weekDay(y) { |
| // 1/1/1970 was a Thursday. |
| return (_dayFromYear(y) + 4) % 7; |
| } |
| |
| /** |
| * Returns a year in the range 2008-2035 matching |
| * * leap year, and |
| * * week day of first day. |
| * |
| * Leap seconds are ignored. |
| * Adapted from V8's date implementation. See ECMA 262 - 15.9.1.9. |
| */ |
| static int _equivalentYear(int year) { |
| // Returns year y so that _weekDay(y) == _weekDay(year). |
| // _weekDay returns the week day (in range 0 - 6). |
| // 1/1/1956 was a Sunday (i.e. weekday 0). 1956 was a leap-year. |
| // 1/1/1967 was a Sunday (i.e. weekday 0). |
| // Without leap years a subsequent year has a week day + 1 (for example |
| // 1/1/1968 was a Monday). With leap-years it jumps over one week day |
| // (e.g. 1/1/1957 was a Tuesday). |
| // After 12 years the weekdays have advanced by 12 days + 3 leap days = |
| // 15 days. 15 % 7 = 1. So after 12 years the week day has always |
| // (now independently of leap-years) advanced by one. |
| // weekDay * 12 gives thus a year starting with the wanted weekDay. |
| int recentYear = (_isLeapYear(year) ? 1956 : 1967) + (_weekDay(year) * 12); |
| // Close to the year 2008 the calendar cycles every 4 * 7 years (4 for the |
| // leap years, 7 for the weekdays). |
| // Find the year in the range 2008..2037 that is equivalent mod 28. |
| return 2008 + (recentYear - 2008) % 28; |
| } |
| |
| /** |
| * Returns the UTC year for the corresponding [secondsSinceEpoch]. |
| * It is relatively fast for values in the range 0 to year 2098. |
| * |
| * Code is adapted from V8. |
| */ |
| static int _yearsFromSecondsSinceEpoch(int secondsSinceEpoch) { |
| const int DAYS_IN_4_YEARS = 4 * 365 + 1; |
| const int DAYS_IN_100_YEARS = 25 * DAYS_IN_4_YEARS - 1; |
| const int DAYS_YEAR_2098 = DAYS_IN_100_YEARS + 6 * DAYS_IN_4_YEARS; |
| |
| int days = secondsSinceEpoch ~/ Duration.secondsPerDay; |
| if (days > 0 && days < DAYS_YEAR_2098) { |
| // According to V8 this fast case works for dates from 1970 to 2099. |
| return 1970 + (4 * days + 2) ~/ DAYS_IN_4_YEARS; |
| } |
| int micros = secondsSinceEpoch * Duration.microsecondsPerSecond; |
| return _computeUpperPart(micros)[_YEAR_INDEX]; |
| } |
| |
| /** |
| * Returns a date in seconds that is equivalent to the given |
| * date in microseconds [microsecondsSinceEpoch]. An equivalent |
| * date has the same fields (`month`, `day`, etc.) as the given |
| * date, but the `year` is in the range [1901..2038]. |
| * |
| * * The time since the beginning of the year is the same. |
| * * If the given date is in a leap year then the returned |
| * seconds are in a leap year, too. |
| * * The week day of given date is the same as the one for the |
| * returned date. |
| */ |
| static int _equivalentSeconds(int microsecondsSinceEpoch) { |
| const int CUT_OFF_SECONDS = 0x7FFFFFFF; |
| |
| int secondsSinceEpoch = _flooredDivision( |
| microsecondsSinceEpoch, Duration.microsecondsPerSecond); |
| |
| if (secondsSinceEpoch.abs() > CUT_OFF_SECONDS) { |
| int year = _yearsFromSecondsSinceEpoch(secondsSinceEpoch); |
| int days = _dayFromYear(year); |
| int equivalentYear = _equivalentYear(year); |
| int equivalentDays = _dayFromYear(equivalentYear); |
| int diffDays = equivalentDays - days; |
| secondsSinceEpoch += diffDays * Duration.secondsPerDay; |
| } |
| return secondsSinceEpoch; |
| } |
| |
| static int _timeZoneOffsetInSeconds(int microsecondsSinceEpoch) { |
| int equivalentSeconds = _equivalentSeconds(microsecondsSinceEpoch); |
| return _timeZoneOffsetInSecondsForClampedSeconds(equivalentSeconds); |
| } |
| |
| static String _timeZoneName(int microsecondsSinceEpoch) { |
| int equivalentSeconds = _equivalentSeconds(microsecondsSinceEpoch); |
| return _timeZoneNameForClampedSeconds(equivalentSeconds); |
| } |
| |
| /// Finds the local time corresponding to a UTC date and time. |
| /// |
| /// The [microsecondsSinceEpoch] represents a particular |
| /// calendar date and clock time in UTC. |
| /// This methods returns a (usually different) point in time |
| /// where the local time had the same calendar date and clock |
| /// time (if such a time exists, otherwise it finds the "best" |
| /// substitute). |
| /// |
| /// A valid result is a point in time `microsecondsSinceEpoch - offset` |
| /// where the local time zone offset is `+offset`. |
| /// |
| /// In some cases there are two valid results, due to a time zone |
| /// change setting the clock back (for example exiting from daylight |
| /// saving time). In that case, we return the *earliest* valid result. |
| /// |
| /// In some cases there are no valid results, due to a time zone |
| /// change setting the clock forward (for example entering daylight |
| /// saving time). In that case, we return the time which would have |
| /// been correct in the earlier time zone (so asking for 2:30 AM |
| /// when clocks move directly from 2:00 to 3:00 will give the |
| /// time that *would have been* 2:30 in the earlier time zone, |
| /// which is now 3:30 in the local time zone). |
| /// |
| /// Returns the point in time as a number of microseconds since epoch. |
| static int _toLocalTimeOffset(int microsecondsSinceEpoch) { |
| // Argument is the UTC time corresponding to the desired |
| // calendar date/wall time. |
| // We now need to find an UTC time where the difference |
| // from `microsecondsSinceEpoch` is the same as the |
| // local time offset at that time. That is, we want to |
| // find `adjustment` in microseconds such that: |
| // |
| // _timeZoneOffsetInSeconds(microsecondsSinceEpoch - offset) |
| // * Duration.microsecondsPerSecond == offset |
| // |
| // Such an offset might not exist, if that wall time |
| // is skipped when a time zone change moves the clock forwards. |
| // In that case we pick a time after the switch which would be |
| // correct in the previous time zone. |
| // Also, there might be more than one solution if a time zone |
| // change moves the clock backwards and the same wall clock |
| // time occurs twice in the same day. |
| // In that case we pick the one in the time zone prior to |
| // the switch. |
| |
| // Start with the time zone at the current microseconds since |
| // epoch. It's within one day of the real time we're looking for. |
| |
| int offset = _timeZoneOffsetInSeconds(microsecondsSinceEpoch) * |
| Duration.microsecondsPerSecond; |
| |
| // If offset is 0 (we're right around the UTC+0, and) |
| // we have found one solution. |
| if (offset != 0) { |
| // If not, try to find an actual solution in the time zone |
| // we just discovered. |
| int offset2 = _timeZoneOffsetInSeconds(microsecondsSinceEpoch - offset) * |
| Duration.microsecondsPerSecond; |
| if (offset2 != offset) { |
| // Also not a solution. We have found a second time zone |
| // within the same day. We assume that's all there are. |
| // Try again with the new time zone. |
| int offset3 = |
| _timeZoneOffsetInSeconds(microsecondsSinceEpoch - offset2) * |
| Duration.microsecondsPerSecond; |
| // Either offset3 is a solution (equal to offset2), |
| // or we have found two different time zones and no solution. |
| // In the latter case we choose the lower offset (latter time). |
| return (offset2 <= offset3 ? offset2 : offset3); |
| } |
| // We have found one solution and one time zone. |
| offset = offset2; |
| } |
| // Try to see if there is an earlier time zone which also |
| // has a solution. |
| // Pretends time zone changes are always at most two hours. |
| // (Double daylight saving happened, fx, in part of Canada in 1988). |
| int offset4 = _timeZoneOffsetInSeconds(microsecondsSinceEpoch - |
| offset - |
| 2 * Duration.microsecondsPerHour) * |
| Duration.microsecondsPerSecond; |
| if (offset4 > offset) { |
| // The time zone at the earlier time had a greater |
| // offset, so it's possible that the desired wall clock |
| // occurs in that time zone too. |
| if (offset4 == offset + 2 * Duration.microsecondsPerHour) { |
| // A second and earlier solution, so use that. |
| return offset4; |
| } |
| // The time zone differs one hour earlier, but not by one |
| // hour, so check again in that time zone. |
| int offset5 = _timeZoneOffsetInSeconds(microsecondsSinceEpoch - offset4) * |
| Duration.microsecondsPerSecond; |
| if (offset5 == offset4) { |
| // Found a second solution earlier than the first solution, so use that. |
| return offset4; |
| } |
| } |
| // Did not find a solution in the earlier time |
| // zone, so just use the original result. |
| return offset; |
| } |
| } |
