parse method

Implementation

@override
Result<String>? parse(State<StringReader> state) {
  final pos = state.pos;
  final r1 = p1.parse(state);
  if (r1 != null) {
    final r2 = p2.parse(state);
    if (r2 != null) {
      final r3 = p3.parse(state);
      if (r3 != null) {
        final r4 = p4.parse(state);
        if (r4 != null) {
          final r5 = p5.parse(state);
          if (r5 != null) {
            final r6 = p6.parse(state);
            if (r6 != null) {
              final r7 = p7.parse(state);
              if (r7 != null) {
                return state.pos != pos
                    ? Result(state.input.substring(pos, state.pos))
                    : const Result('');
              }
            }
          }
        }
      }
    }
  }

  state.pos = pos;
  return null;
}