parseAsync method

Implementation

@override
AsyncResult<String> parseAsync(State<ChunkedData<StringReader>> state) {
  final result = AsyncResult<String>();
  if (!backtrack(state)) {
    result.ok = false;
    return result;
  }

  final input = state.input;
  final start = input.start;
  final pos = state.pos;
  input.buffering++;
  void parse() {
    final data = input.data;
    final source = data.source;
    final end = input.end;
    var ok = true;
    int? c;
    while (state.pos < end) {
      c = source.runeAt(state.pos - start);
      if (!(c >= 0x41 && c <= 0x5A || c >= 0x61 && c <= 0x7A)) {
        ok = false;
        break;
      }

      state.pos += c > 0xffff ? 2 : 1;
    }

    if (ok && !input.isClosed) {
      input.sleep = true;
      input.handler = parse;
      return;
    }

    input.buffering--;
    if (result.ok = state.pos != pos) {
      result.value = Result(source.substring(pos - start, state.pos - start));
    } else {
      state.fail<Object?>(ErrorUnexpectedCharacter(c));
    }

    input.handler = result.handler;
  }

  parse();
  return result;
}