parse static method

IsoDuration parse(String textValue)

Parses the given textValue into a duration.

The formmat is defined as P[n]Y[n]M[n]DT[n]H[n]M[n]S Example: P3WT1H means 3 weeks and 1 hour. Compare https://en.wikipedia.org/wiki/ISO_8601#Durations

Implementation

static IsoDuration parse(String textValue) {
  /// Note ISO_8601 allows floating numbers, compare https://en.wikipedia.org/wiki/ISO_8601#Durations,
  /// but even the validator https://icalendar.org/validator.html does not accept floating numbers.
  ///  So this implementation expects integers, too
  if (!(textValue.startsWith('P') || textValue.startsWith('-P'))) {
    throw FormatException(
        'duration content needs to start with P, $textValue is invalid');
  }
  final isNegativeDuration = textValue.startsWith('-');
  if (isNegativeDuration) {
    textValue = textValue.substring(1);
  }
  var years = 0, months = 0, weeks = 0, days = 0;
  var startIndex = 1;
  if (!textValue.startsWith('PT')) {
    final timeIndex = textValue.indexOf('T');
    final yearsResult = _parseSection(textValue, startIndex, 'Y');
    startIndex = yearsResult.index;
    years = yearsResult.result;
    final monthsResult = _parseSection(textValue, startIndex, 'M',
        maxIndex: timeIndex); // M can also stand for minutes after the T
    startIndex = monthsResult.index;
    months = monthsResult.result;
    final weeksResult = _parseSection(textValue, startIndex, 'W');
    startIndex = weeksResult.index;
    weeks = weeksResult.result;
    final daysResult = _parseSection(textValue, startIndex, 'D');
    startIndex = daysResult.index;
    days = daysResult.result;
  }
  var hours = 0, minutes = 0, seconds = 0;
  if (startIndex < textValue.length && textValue[startIndex] == 'T') {
    startIndex++;
    final hoursResult = _parseSection(textValue, startIndex, 'H');
    hours = hoursResult.result;
    startIndex = hoursResult.index;
    final minutesResult = _parseSection(textValue, startIndex, 'M');
    minutes = minutesResult.result;
    startIndex = minutesResult.index;
    final secondsResult = _parseSection(textValue, startIndex, 'S');
    seconds = secondsResult.result;
  }

  return IsoDuration(
    years: years,
    months: months,
    weeks: weeks,
    days: days,
    hours: hours,
    minutes: minutes,
    seconds: seconds,
    isNegativeDuration: isNegativeDuration,
  );
}