parse method

Implementation

@override
Result<({int start, int end, String value})>? parse(
    State<StringReader> state) {
  final input = state.input;
  final length = input.length;
  final pos = state.pos;
  if (state.pos < length) {
    while (state.pos < length) {
      final start = state.pos;
      final r = p.parse(state);
      if (r == null) {
        input.readChar(state.pos);
        state.pos += input.count;
      } else {
        final v = input.substring(start, state.pos);
        return Result((start: start, end: state.pos, value: v));
      }
    }
  }

  state.pos = pos;
  return state.fail(const ErrorUnexpectedEndOfInput());
}