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Unified Diff: runtime/lib/date.dart

Issue 10533068: Refactor Date implementation in VM. (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Minor cosmetic changes in the comments. Created 8 years, 6 months ago
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Index: runtime/lib/date.dart
diff --git a/runtime/lib/date.dart b/runtime/lib/date.dart
index d39fb8cf92fc4108caf1d4f1583de18d838fc8c2..8112c6278cf6116e46c100273992c3d8391e3a64 100644
--- a/runtime/lib/date.dart
+++ b/runtime/lib/date.dart
@@ -5,7 +5,7 @@
// VM implementation of DateImplementation.
class DateImplementation implements Date {
- static final int _SECONDS_YEAR_2035 = 2051222400;
+ static final int _MAX_VALUE = 8640000000000000;
DateImplementation(int years,
[int month = 1,
@@ -80,11 +80,14 @@ class DateImplementation implements Date {
}
DateImplementation.fromEpoch(int this.value, [bool isUtc = false])
- : _isUtc = isUtc;
+ : _isUtc = isUtc {
+ if (value.abs() > _MAX_VALUE) throw new IllegalArgumentException(value);
+ }
bool operator ==(Object other) {
if (other is !DateImplementation) return false;
- return value == other.value;
+ DateImplementation otherDate = other;
+ return value == otherDate.value;
}
bool operator <(Date other) => value < other.value;
@@ -110,79 +113,56 @@ class DateImplementation implements Date {
String get timeZoneName() {
if (isUtc()) return "UTC";
- return _timeZoneName(_equivalentSeconds(_secondsSinceEpoch));
+ return _timeZoneName(value);
}
Duration get timeZoneOffset() {
if (isUtc()) return new Duration(0);
- int offsetInSeconds =
- _timeZoneOffsetInSeconds(_equivalentSeconds(_secondsSinceEpoch));
+ int offsetInSeconds = _timeZoneOffsetInSeconds(value);
return new Duration(seconds: offsetInSeconds);
}
int get year() {
- int secondsSinceEpoch = _secondsSinceEpoch;
- // According to V8 some library calls have troubles with negative values.
- // Therefore clamp to 0 - year 2035 (which is less than the size of 32bit).
- if (secondsSinceEpoch >= 0 && secondsSinceEpoch < _SECONDS_YEAR_2035) {
- return _getYear(secondsSinceEpoch, isUtc());
- }
-
- // Approximate the result. We don't take timeZone into account.
- int approximateYear = _yearsFromSecondsSinceEpoch(secondsSinceEpoch);
- int equivalentYear = _equivalentYear(approximateYear);
- int y = _getYear(_equivalentSeconds(_secondsSinceEpoch), isUtc());
- return approximateYear + (y - equivalentYear);
+ return _decomposeIntoYearMonthDay(_localDateInUtcValue)[0];
}
int get month() {
- return _getMonth(_equivalentSeconds(_secondsSinceEpoch), isUtc());
+ return _decomposeIntoYearMonthDay(_localDateInUtcValue)[1];
}
int get day() {
- return _getDay(_equivalentSeconds(_secondsSinceEpoch), isUtc());
+ return _decomposeIntoYearMonthDay(_localDateInUtcValue)[2];
}
int get hours() {
- return _getHours(_equivalentSeconds(_secondsSinceEpoch), isUtc());
+ int valueInHours = _flooredDivision(_localDateInUtcValue,
+ Duration.MILLISECONDS_PER_HOUR);
+ return valueInHours % Duration.HOURS_PER_DAY;
}
int get minutes() {
- return _getMinutes(_equivalentSeconds(_secondsSinceEpoch), isUtc());
+ int valueInMinutes = _flooredDivision(_localDateInUtcValue,
+ Duration.MILLISECONDS_PER_MINUTE);
+ return valueInMinutes % Duration.MINUTES_PER_HOUR;
}
int get seconds() {
- return _getSeconds(_equivalentSeconds(_secondsSinceEpoch), isUtc());
+ // Seconds are unaffected by the timezone the user is in. So we can
+ // directly use the value and not the [_localDateInUtcValue].
+ int valueInSeconds =
+ _flooredDivision(value, Duration.MILLISECONDS_PER_SECOND);
+ return valueInSeconds % Duration.SECONDS_PER_MINUTE;
}
int get milliseconds() {
+ // Milliseconds are unaffected by the timezone the user is in. So we can
+ // directly use the value and not the [_localDateInUtcValue].
return value % Duration.MILLISECONDS_PER_SECOND;
}
- int get _secondsSinceEpoch() {
- // Always round down.
- if (value < 0) {
- return (value + 1) ~/ Duration.MILLISECONDS_PER_SECOND - 1;
- } else {
- return value ~/ Duration.MILLISECONDS_PER_SECOND;
- }
- }
-
int get weekday() {
- final Date unixTimeStart = new Date(1970, 1, 1, 0, 0, 0, 0, isUtc());
- int msSince1970 = this.difference(unixTimeStart).inMilliseconds;
- // Adjust the milliseconds to avoid problems with summer-time.
- if (hours < 2) {
- msSince1970 += 2 * Duration.MILLISECONDS_PER_HOUR;
- }
- // Compute the floor of msSince1970 / Duration.MS_PER_DAY.
- int daysSince1970;
- if (msSince1970 >= 0) {
- daysSince1970 = msSince1970 ~/ Duration.MILLISECONDS_PER_DAY;
- } else {
- daysSince1970 = (msSince1970 - Duration.MILLISECONDS_PER_DAY + 1) ~/
- Duration.MILLISECONDS_PER_DAY;
- }
+ int daysSince1970 =
+ _flooredDivision(_localDateInUtcValue, Duration.MILLISECONDS_PER_DAY);
// 1970-1-1 was a Thursday.
return ((daysSince1970 + Date.THU) % Date.DAYS_IN_WEEK);
}
@@ -222,27 +202,34 @@ class DateImplementation implements Date {
}
}
- // Adds the [duration] to this Date instance.
+ /** Returns a new [Date] with the [duration] added to [this]. */
Date add(Duration duration) {
return new DateImplementation.fromEpoch(value + duration.inMilliseconds,
isUtc());
}
- // Subtracts the [duration] from this Date instance.
+ /** Returns a new [Date] with the [duration] subtracted from [this]. */
Date subtract(Duration duration) {
return new DateImplementation.fromEpoch(value - duration.inMilliseconds,
isUtc());
}
- // Returns a [Duration] with the difference of [this] and [other].
+ /** Returns a [Duration] with the difference of [this] and [other]. */
Duration difference(Date other) {
return new DurationImplementation(milliseconds: value - other.value);
}
- // Returns the UTC year for the corresponding [secondsSinceEpoch].
- // It is relatively fast for values in the range 0 to year 2098.
+ /** The first list contains the days until each month in non-leap years. The
+ * second list contains the days in leap years. */
+ static final 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]];
+
+ // Returns the UTC year, month and day for the corresponding
+ // [millisecondsSinceEpoch].
// Code is adapted from V8.
- static int _yearsFromSecondsSinceEpoch(int secondsSinceEpoch) {
+ static List<int> _decomposeIntoYearMonthDay(int millisecondsSinceEpoch) {
+ // TODO(floitsch): cache result.
final int DAYS_IN_4_YEARS = 4 * 365 + 1;
final int DAYS_IN_100_YEARS = 25 * DAYS_IN_4_YEARS - 1;
final int DAYS_IN_400_YEARS = 4 * DAYS_IN_100_YEARS + 1;
@@ -250,76 +237,143 @@ class DateImplementation implements Date {
final int DAYS_OFFSET = 1000 * DAYS_IN_400_YEARS + 5 * DAYS_IN_400_YEARS -
DAYS_1970_TO_2000;
final int YEARS_OFFSET = 400000;
- final int DAYS_YEAR_2098 = DAYS_IN_100_YEARS + 6 * DAYS_IN_4_YEARS;
- int days = secondsSinceEpoch ~/ Duration.SECONDS_PER_DAY;
- 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;
- } else {
- days += DAYS_OFFSET;
- int result = 400 * (days ~/ DAYS_IN_400_YEARS) - YEARS_OFFSET;
- days = days.remainder(DAYS_IN_400_YEARS);
- days--;
- int yd1 = days ~/ DAYS_IN_100_YEARS;
- days = days.remainder(DAYS_IN_100_YEARS);
- result += 100 * yd1;
- days++;
- int yd2 = days ~/ DAYS_IN_4_YEARS;
- days = days.remainder(DAYS_IN_4_YEARS);
- result += 4 * yd2;
- days--;
- int yd3 = days ~/ 365;
- days = days.remainder(365);
- result += yd3;
- return result;
+ int resultYear = 0;
+ int resultMonth = 0;
+ int resultDay = 0;
+
+ // Always round down.
+ int days = _flooredDivision(millisecondsSinceEpoch,
+ Duration.MILLISECONDS_PER_DAY);
+ days += DAYS_OFFSET;
+ resultYear = 400 * (days ~/ DAYS_IN_400_YEARS) - YEARS_OFFSET;
+ days = days.remainder(DAYS_IN_400_YEARS);
+ days--;
+ int yd1 = days ~/ DAYS_IN_100_YEARS;
+ days = days.remainder(DAYS_IN_100_YEARS);
+ resultYear += 100 * yd1;
+ days++;
+ int yd2 = days ~/ DAYS_IN_4_YEARS;
+ days = days.remainder(DAYS_IN_4_YEARS);
+ resultYear += 4 * yd2;
+ days--;
+ int yd3 = days ~/ 365;
+ days = 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;
+ return <int>[resultYear, resultMonth, resultDay];
}
- // Given [secondsSinceEpoch] returns seconds such that they are at the same
- // time in an equivalent year (see [_equivalentYear]).
- // Leap seconds are ignored.
- static int _equivalentSeconds(int secondsSinceEpoch) {
- if (secondsSinceEpoch >= 0 && secondsSinceEpoch < _SECONDS_YEAR_2035) {
- return secondsSinceEpoch;
- }
- int year = _yearsFromSecondsSinceEpoch(secondsSinceEpoch);
- int days = _dayFromYear(year);
- int equivalentYear = _equivalentYear(year);
- int equivalentDays = _dayFromYear(equivalentYear);
- int diffDays = equivalentDays - days;
- return secondsSinceEpoch + diffDays * Duration.SECONDS_PER_DAY;
+ /**
+ * Returns the amount of milliseconds in UTC that represent the same values as
+ * [this].
+ *
+ * Say [:t:] is the result of this function, then
+ * * [:this.year == new Date.fromEpoch(t, isUtc: true).year:],
+ * * [:this.month == new Date.fromEpoch(t, isUtc: true).month:],
+ * * [:this.day == new Date.fromEpoch(t, isUtc: true).day:],
+ * * [:this.hours == new Date.fromEpoch(t, isUtc: true).hours:],
+ * * ...
+ *
+ * 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 _localDateInUtcValue() {
+ if (isUtc()) return value;
+ int offset =
+ _timeZoneOffsetInSeconds(value) * Duration.MILLISECONDS_PER_SECOND;
+ return value - 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) {
- int flooredDivision(int a, int b) {
- return (a - (a < 0 ? b - 1 : 0)) ~/ b;
- }
-
return 365 * (year - 1970)
- + flooredDivision(year - 1969, 4)
- - flooredDivision(year - 1901, 100)
- + flooredDivision(year - 1601, 400);
+ + _flooredDivision(year - 1969, 4)
+ - _flooredDivision(year - 1901, 100)
+ + _flooredDivision(year - 1601, 400);
}
- // 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 _equivalentYear(int year) {
- // Returns 1 if in leap year. 0 otherwise.
- bool inLeapYear(year) {
- return (year.remainder(4) == 0) &&
- ((year.remainder(100) != 0) || (year.remainder(400) == 0));
+ static bool _isLeapYear(y) {
+ return (y.remainder(4) == 0) &&
+ ((y.remainder(100) != 0) || (y.remainder(400) == 0));
+ }
+
+ static _brokenDownDateToMillisecondsSinceEpoch(
+ int years, int month, int day,
+ int hours, int minutes, int seconds, int milliseconds,
+ bool isUtc) {
+ if ((month < 1) || (month > 12)) return null;
+ if ((day < 1) || (day > 31)) return null;
+ // Leap seconds can lead to hours == 24.
+ if ((hours < 0) || (hours > 24)) return null;
+ if ((hours == 24) && ((minutes != 0) || (seconds != 0))) return null;
+ if ((minutes < 0) || (minutes > 59)) return null;
+ if ((seconds < 0) || (seconds > 59)) return null;
+ if ((milliseconds < 0) || (milliseconds > 999)) return null;
+
+ // 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(years) ? 1 : 0][month - 1];
+ days += _dayFromYear(years);
+ int millisecondsSinceEpoch = days * Duration.MILLISECONDS_PER_DAY +
+ hours * Duration.MILLISECONDS_PER_HOUR +
+ minutes * Duration.MILLISECONDS_PER_MINUTE+
+ seconds * Duration.MILLISECONDS_PER_SECOND +
+ milliseconds;
+
+ // 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 (millisecondsSinceEpoch.abs() >
+ (_MAX_VALUE + Duration.MILLISECONDS_PER_DAY)) {
+ return null;
}
+ if (!isUtc) {
+ // Note that we need to add the local timezone adjustement before asking
+ // for the correct zone offset.
+ int adjustment = _localTimeZoneAdjustmentInSeconds() *
+ Duration.MILLISECONDS_PER_SECOND;
+ int zoneOffset =
+ _timeZoneOffsetInSeconds(millisecondsSinceEpoch + adjustment);
+ millisecondsSinceEpoch += zoneOffset * Duration.MILLISECONDS_PER_SECOND;
+ }
+ if (millisecondsSinceEpoch.abs() > _MAX_VALUE) return null;
+ return millisecondsSinceEpoch;
+ }
+
+ /**
+ * 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 _equivalentYear(int year) {
// Returns the week day (in range 0 - 6).
- int weekDay(year) {
+ int weekDay(y) {
// 1/1/1970 was a Thursday.
- return (_dayFromYear(year) + 4) % 7;
+ return (_dayFromYear(y) + 4) % 7;
}
// 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).
@@ -330,82 +384,82 @@ class DateImplementation implements Date {
// 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 = (inLeapYear(year) ? 1956 : 1967) + (weekDay(year) * 12);
+ 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;
}
- static _brokenDownDateToMillisecondsSinceEpoch(
- int years, int month, int day,
- int hours, int minutes, int seconds, int milliseconds,
- bool isUtc) {
- if ((month < 1) || (month > 12)) return null;
- if ((day < 1) || (day > 31)) return null;
- // Leap seconds can lead to hours == 24.
- if ((hours < 0) || (hours > 24)) return null;
- if ((hours == 24) && ((minutes != 0) || (seconds != 0))) return null;
- if ((minutes < 0) || (minutes > 59)) return null;
- if ((seconds < 0) || (seconds > 59)) return null;
- if ((milliseconds < 0) || (milliseconds > 999)) return null;
+ /**
+ * 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) {
+ final int DAYS_IN_4_YEARS = 4 * 365 + 1;
+ final int DAYS_IN_100_YEARS = 25 * DAYS_IN_4_YEARS - 1;
+ final int DAYS_YEAR_2098 = DAYS_IN_100_YEARS + 6 * DAYS_IN_4_YEARS;
- int equivalentYear;
- int offsetInSeconds;
- // According to V8 some library calls have troubles with negative values.
- // Therefore clamp to 1970 - year 2035 (which is less than the size of
- // 32bit).
- // We exclude the year 1970 when the time is not UTC, since the epoch
- // value could then be negative.
- if (years < (isUtc ? 1970 : 1971) || years > 2035) {
- equivalentYear = _equivalentYear(years);
- int offsetInDays = (_dayFromYear(years) - _dayFromYear(equivalentYear));
- // Leap seconds are ignored.
- offsetInSeconds = offsetInDays * Duration.SECONDS_PER_DAY;
- } else {
- equivalentYear = years;
- offsetInSeconds = 0;
+ int days = secondsSinceEpoch ~/ Duration.SECONDS_PER_DAY;
+ 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 secondsSinceEpoch = _brokenDownDateToSecondsSinceEpoch(
- equivalentYear, month, day, hours, minutes, seconds, isUtc);
- int adjustedSeconds = secondsSinceEpoch + offsetInSeconds;
- return adjustedSeconds * Duration.MILLISECONDS_PER_SECOND + milliseconds;
+ int ms = secondsSinceEpoch * Duration.MILLISECONDS_PER_SECOND;
+ return _decomposeIntoYearMonthDay(ms)[0];
+ }
+
+ /**
+ * Returns a date in seconds that is equivalent to the current date. An
+ * equivalent date has the same fields ([:month:], [:day:], etc.) as the
+ * [this], but the [:year:] is in the range [1970..2037].
+ *
+ * * The time since the beginning of the year is the same.
+ * * If [this] is in a leap year then the returned seconds are in a leap
+ * year, too.
+ * * The week day of [this] is the same as the one for the returned date.
+ */
+ static int _equivalentSeconds(int millisecondsSinceEpoch) {
+ final int CUT_OFF_SECONDS = 2100000000;
+
+ int secondsSinceEpoch = _flooredDivision(millisecondsSinceEpoch,
+ Duration.MILLISECONDS_PER_SECOND);
+
+ if (secondsSinceEpoch < 0 || secondsSinceEpoch >= 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.SECONDS_PER_DAY;
+ }
+ return secondsSinceEpoch;
+ }
+
+ static int _timeZoneOffsetInSeconds(int millisecondsSinceEpoch) {
+ int equivalentSeconds = _equivalentSeconds(millisecondsSinceEpoch);
+ return _timeZoneOffsetInSecondsForClampedSeconds(equivalentSeconds);
+ }
+
+ static String _timeZoneName(int millisecondsSinceEpoch) {
+ int equivalentSeconds = _equivalentSeconds(millisecondsSinceEpoch);
+ return _timeZoneNameForClampedSeconds(equivalentSeconds);
}
final bool _isUtc;
final int value;
-
// Natives
- static _brokenDownDateToSecondsSinceEpoch(
- int years, int month, int day, int hours, int minutes, int seconds,
- bool isUtc) native "DateNatives_brokenDownToSecondsSinceEpoch";
-
static int _getCurrentMs() native "DateNatives_currentTimeMillis";
- static String _timeZoneName(int secondsSinceEpoch)
+ static String _timeZoneNameForClampedSeconds(int secondsSinceEpoch)
native "DateNatives_timeZoneName";
- static int _timeZoneOffsetInSeconds(int secondsSinceEpoch)
+ static int _timeZoneOffsetInSecondsForClampedSeconds(int secondsSinceEpoch)
native "DateNatives_timeZoneOffsetInSeconds";
- // TODO(floitsch): it would be more efficient if we didn't call the native
- // function for every member, but cached the broken-down date.
- static int _getYear(int secondsSinceEpoch, bool isUtc)
- native "DateNatives_getYear";
-
- static int _getMonth(int secondsSinceEpoch, bool isUtc)
- native "DateNatives_getMonth";
-
- static int _getDay(int secondsSinceEpoch, bool isUtc)
- native "DateNatives_getDay";
-
- static int _getHours(int secondsSinceEpoch, bool isUtc)
- native "DateNatives_getHours";
-
- static int _getMinutes(int secondsSinceEpoch, bool isUtc)
- native "DateNatives_getMinutes";
-
- static int _getSeconds(int secondsSinceEpoch, bool isUtc)
- native "DateNatives_getSeconds";
+ static int _localTimeZoneAdjustmentInSeconds()
+ native "DateNatives_localTimeZoneAdjustmentInSeconds";
}
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