parseAsync method

Implementation

@override
void parseAsync(
    State<ChunkedData<StringReader>> state, ResultCallback<int> onDone) {
  if (!backtrack(state)) {
    onDone(null);
    return;
  }

  final input = state.input;
  input.buffering++;
  void parse() {
    final end = input.end;
    if (state.pos >= end && !input.isClosed) {
      input.sleep = true;
      input.handle(parse);
      return;
    }

    final data = input.data;
    input.buffering--;
    if (state.pos < end) {
      final source = data.source!;
      final c = source.runeAt(state.pos - input.start);
      if (c == char) {
        state.pos += c > 0xffff ? 2 : 1;
        onDone(Result(c));
        return;
      }
    }

    state.fail<Object?>(ErrorExpectedCharacter(char));
    onDone(null);
  }

  parse();
}