parse static method

NepaliDateTime parse(String formattedString)

Constructs a new DateTime instance based on formattedString.

Throws a FormatException if the input cannot be parsed.

Implementation

static NepaliDateTime parse(String formattedString) {
  final re = _parseFormat;
  final Match? match = re.firstMatch(formattedString);
  if (match != null) {
    int parseIntOrZero(String? matched) {
      if (matched == null) return 0;
      return int.parse(matched);
    }

    // Parses fractional second digits of '.(\d+)' into the combined
    // microseconds. We only use the first 6 digits because of DateTime
    // precision of 999 milliseconds and 999 microseconds.
    int parseMilliAndMicroseconds(String? matched) {
      if (matched == null) return 0;
      final length = matched.length;
      assert(length >= 1, 'matched string is empty');
      var result = 0;
      for (var i = 0; i < 6; i++) {
        result *= 10;
        if (i < matched.length) {
          result += matched.codeUnitAt(i) ^ 0x30;
        }
      }
      return result;
    }

    final years = int.parse(match[1]!);
    final month = int.parse(match[2]!);
    final day = int.parse(match[3]!);
    final hour = parseIntOrZero(match[4]);
    final minute = parseIntOrZero(match[5]);
    final second = parseIntOrZero(match[6]);
    final milliAndMicroseconds = parseMilliAndMicroseconds(match[7]);
    final millisecond =
        milliAndMicroseconds ~/ Duration.microsecondsPerMillisecond;
    final microsecond =
        milliAndMicroseconds.remainder(Duration.microsecondsPerMillisecond);

    return NepaliDateTime(
      years,
      month,
      day,
      hour,
      minute,
      second,
      millisecond,
      microsecond,
    );
  } else {
    throw FormatException('Invalid NepaliDateTime format', formattedString);
  }
}