groupByString function

List<String> groupByString(bool groupFunction(String a, String b), String s)

Group characters together if they meet criteria.

Implementation

List<String> groupByString(
    bool Function(String a, String b) groupFunction, String s) {
  if (s.isEmpty) {
    return [];
  }
  List<String> groups = [];
  String currentGroup = s.substring(0, 1);
  for (int i = 1; i < s.length; i++) {
    if (groupFunction(s.substring(i - 1, i), s.substring(i, i + 1))) {
      currentGroup += (s.substring(i, i + 1));
      if (i == s.length - 1) {
        groups.add(currentGroup);
      }
    } else {
      groups.add(currentGroup);
      currentGroup = s.substring(i, i + 1);
      if (i == s.length - 1) {
        groups.add(currentGroup);
      }
      continue;
    }
  }
  return groups;
}