strtok_r method

String? strtok_r(String? str, String delim, List<String> saveptr)

Reentrant string tokenization.

Because Dart does not have out-parameters, we simulate saveptr by passing a List<String> of length 1 to hold the state. Example: List<String> state = [""]; strtok_r(str, delim, state);

Implementation

String? strtok_r(String? str, String delim, List<String> saveptr) {
  if (saveptr.isEmpty) saveptr.add("");

  String state;
  if (str != null) {
    state = str;
  } else {
    if (saveptr[0].isEmpty) return null;
    state = saveptr[0];
  }

  int start = 0;
  while (start < state.length && delim.contains(state[start])) {
    start++;
  }

  if (start >= state.length) {
    saveptr[0] = "";
    return null;
  }

  int end = start;
  while (end < state.length && !delim.contains(state[end])) {
    end++;
  }

  String token = state.substring(start, end);

  if (end < state.length) {
    saveptr[0] = state.substring(end + 1);
  } else {
    saveptr[0] = "";
  }

  return token;
}