parse method

@override Tuple1? parse(ParseInput<I> input, ParseState state)

Implementation

@override
Tuple1? parse(ParseInput<I> input, ParseState state) {
  final pos = input.pos;
  if (p1.parse(input, state) != null) {
    if (p2.parse(input, state) != null) {
      if (p3.parse(input, state) != null) {
        if (p4.parse(input, state) != null) {
          return const Tuple1(null);
        }
      }
    }
  }

  input.pos = pos;
}