asDate method

DateTime asDate({ int retries = 3, })

Return a date built using our values. If no date portion is set, use the 'Epoch' of January 1, 1970.

Implementation

DateTime asDate({int retries = 3}) {
  // TODO(alanknight): Validate the date, especially for things which
  // can crash the VM, e.g. large month values.
  if (_date != null) return _date!;

  DateTime preliminaryResult;
  final hasCentury = !_hasAmbiguousCentury || year < 0 || year >= 100;
  if (hasCentury) {
    preliminaryResult = _dateTimeConstructor(year, month, dayOrDayOfYear,
        hour24, minute, second, fractionalSecond, utc);
  } else {
    var now = clock.now();
    if (utc) {
      now = now.toUtc();
    }

    const lookBehindYears = 80;
    var lowerDate = _offsetYear(now, -lookBehindYears);
    var upperDate = _offsetYear(now, 100 - lookBehindYears);
    var lowerCentury = (lowerDate.year ~/ 100) * 100;
    var upperCentury = (upperDate.year ~/ 100) * 100;
    preliminaryResult = _dateTimeConstructor(upperCentury + year, month,
        dayOrDayOfYear, hour24, minute, second, fractionalSecond, utc);

    // Our interval must be half-open since there otherwise could be ambiguity
    // for a date that is exactly 20 years in the future or exactly 80 years
    // in the past (mod 100).  We'll treat the lower-bound date as the
    // exclusive bound because:
    // * It's farther away from the present, and we're less likely to care
    //   about it.
    // * By the time this function exits, time will have advanced to favor
    //   the upper-bound date.
    //
    // We don't actually need to check both bounds.
    if (preliminaryResult.compareTo(upperDate) <= 0) {
      // Within range.
      assert(preliminaryResult.compareTo(lowerDate) > 0);
    } else {
      preliminaryResult = _dateTimeConstructor(lowerCentury + year, month,
          dayOrDayOfYear, hour24, minute, second, fractionalSecond, utc);
    }
  }

  if (utc && hasCentury) {
    _date = preliminaryResult;
  } else {
    _date = _correctForErrors(preliminaryResult, retries);
  }
  return _date!;
}