parse static method

EtDatetime parse(String formattedString)

Constructs a new EtDatetime instance based on formattedString.

The formattedString must not be null. Throws a FormatException if the input string cannot be parsed.

The function parses a subset of ISO 8601 which includes the subset accepted by RFC 3339.

The accepted inputs are currently:

• A date: A signed four-to-six digit year, two digit month and two digit day, optionally separated by - characters. Examples: "19700101", "-0004-12-24", "81030-04-01".
• An optional time part, separated from the date by either T or a space. The time part is a two digit hour, then optionally a two digit minutes value, then optionally a two digit seconds value, and then optionally a '.' or ',' followed by at least a one digit second fraction. The minutes and seconds may be separated from the previous parts by a ':'. Examples: "12", "12:30:24.124", "12:30:24,124", "123010.50".

Examples of accepted strings:

• "2012-02-27 13:27:00"
• "2012-02-27 13:27:00.123456789z"
• "2012-02-27 13:27:00,123456789z"
• "20120227 13:27:00"
• "20120227T132700"
• "20120227"
• "[phone]"
• "2012-02-27T14Z"
• "2012-02-27T14+00:00"
• "-123450101 00:00:00 Z": in the year -12345.
• "2002-02-27T14:00:00-0500": Same as "2002-02-27T19:00:00Z"

Implementation

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

    int parseMilliAndMicroseconds(String? matched) {
      if (matched == null) return 0;
      int length = matched.length;
      assert(length >= 1);
      int result = 0;
      for (int i = 0; i < 6; i++) {
        result *= 10;
        if (i < matched.length) {
          result += matched.codeUnitAt(i) ^ 0x30;
        }
      }
      return result;
    }

    int years = int.parse(match[1]!);
    int month = int.parse(match[2]!);
    int day = int.parse(match[3]!);
    int hour = parseIntOrZero(match[4]);
    int minute = parseIntOrZero(match[5]);
    int second = parseIntOrZero(match[6]);
    int milliAndMicroseconds = parseMilliAndMicroseconds(match[7]);
    int millisecond =
        milliAndMicroseconds ~/ Duration.microsecondsPerMillisecond;
    if (match[8] != null) {
      // timezone part
      if (match[9] != null) {
        // timezone other than 'Z' and 'z'.
        int sign = (match[9] == '-') ? -1 : 1;
        int hourDifference = int.parse(match[10]!);
        int minuteDifference = parseIntOrZero(match[11]);
        minuteDifference += 60 * hourDifference;
        minute -= sign * minuteDifference;
      }
    }
    int value =
        _dateToEpoch(years, month, day, hour, minute, second, millisecond);
    int fixedValue = _fixedFromEthiopic(years, month, day);
    if (value == null) {
      throw FormatException("Time out of range", formattedString);
    }
    return EtDatetime._withValue(value, fixedValue);
  } else {
    throw FormatException("Invalid date format", formattedString);
  }
}