parse method

List<int> parse(String chars)

Implementation

List<int> parse(String chars) {
  final ranges = char_class_parser.parseString(chars);
  String rangeToString(int start, int end) {
    return '[#x${start.toRadixString(16)}-#x${end.toRadixString(16)}]';
  }

  for (final range in ranges) {
    final start = range.$0;
    final end = range.$1;
    if (start > end) {
      throw StateError('Invalid range ${rangeToString(start, end)}: $chars');
    }
  }

  ranges.sort((x, y) => x.$0.compareTo(y.$1));
  final first = ranges[0];
  final list = [first.$0, first.$1];
  var prevStart = list[0];
  var prevEnd = list[1];
  for (var i = 1; i < ranges.length; i++) {
    final range = ranges[i];
    final start = range.$0;
    final end = range.$1;
    if (start >= prevStart && start <= prevEnd) {
      if (end > prevEnd) {
        list.last = end;
      }
    } else if (start == prevEnd + 1) {
      if (end > prevEnd) {
        list.last = end;
      }
    } else {
      list.add(start);
      list.add(end);
    }

    prevStart = list[list.length - 2];
    prevEnd = list.last;
  }

  return list;
}