stringToDuration function

Map<String, Object?> stringToDuration(String durationStr)

Parses a duration string ("Xs", "X.Ns") into a google.protobuf.Duration.

Returns {"seconds": int, "nanos": int}.

Throws FormatException if the string does not end with 's'.

Implementation

Map<String, Object?> stringToDuration(String durationStr) {
  if (!durationStr.endsWith('s')) {
    throw FormatException('Duration string must end with "s": $durationStr');
  }

  final body = durationStr.substring(0, durationStr.length - 1);
  final negative = body.startsWith('-');
  final abs = negative ? body.substring(1) : body;

  final dotIndex = abs.indexOf('.');
  int seconds;
  int nanos;

  if (dotIndex == -1) {
    seconds = int.parse(abs);
    nanos = 0;
  } else {
    seconds = int.parse(abs.substring(0, dotIndex));
    final fracStr = abs.substring(dotIndex + 1).padRight(9, '0');
    nanos = int.parse(fracStr.substring(0, 9));
  }

  if (negative) {
    seconds = -seconds;
    if (nanos != 0) nanos = -nanos;
  }

  return {'seconds': seconds, 'nanos': nanos};
}