ILibTimeZone constructor

ILibTimeZone(String id, [ Map<String, dynamic>? allZoneData ])

Create a zone for the IANA id (e.g. 'Europe/Paris'), or the special id 'local' for the system zone. Unknown ids fall back to 'Etc/UTC'.

allZoneData overrides the bundled zoneinfo table; it defaults to the data for the current locale.

Implementation

ILibTimeZone(String id, [Map<String, dynamic>? allZoneData]) : _id = id {
  if (_id == 'local') {
    // System time zone: sample the OS DST-aware offsets via core DateTime.
    // No zoneinfo is loaded; _zone stays null and all offsets come from the
    // platform. getId() remains 'local'.
    _isLocal = true;
    final int year = sampleYear();
    _offsetJan1 = sysWallOffsetMinutes(year, 1, 1, 0, 0);
    _offsetJun1 = sysWallOffsetMinutes(year, 6, 1, 0, 0);
    // Standard offset is the one closest to -inf (min); DST savings is the spread.
    _offset = _offsetJan1 < _offsetJun1 ? _offsetJan1 : _offsetJun1;
    _dstSavings = (_offsetJan1 - _offsetJun1).abs();
    return;
  }
  allZoneData ??= _getZoneData();
  final Object? entry = allZoneData[_id];
  if (entry is String) {
    _zone = allZoneData[entry] as Map<String, dynamic>?;
  } else if (entry is Map<String, dynamic>) {
    _zone = entry;
  } else {
    // Unknown zone id: fall back to Etc/UTC, including its id (getId() returns
    // "Etc/UTC" for an unrecognized zone).
    _zone = allZoneData['Etc/UTC'] as Map<String, dynamic>?;
    _id = 'Etc/UTC';
  }
  if (_zone != null) {
    _offset = _parseOffset(_zone!['o'] as String? ?? '0:0');
    if (_zone!.containsKey('s') && _zone!.containsKey('e')) {
      final Map<String, dynamic> s = _zone!['s'] as Map<String, dynamic>;
      _dstSavings = _parseOffsetMinutes(s['v'] as String? ?? '1:0');
    }
  }
}