parse method

@override Tuple1<Tuple2<E1, E2>>? parse(ParseState state)

Parses input data actively and produces the result.

Returns Tuple1 of the result if parsing was successful; otherwise returns null.

final r1 = p.parse(state);

Implementation

@override
Tuple1<Tuple2<E1, E2>>? parse(ParseState state) {
  final pos = state.pos;
  final r1 = p1.parse(state);
  if (r1 != null) {
    final r2 = p2.parse(state);
    if (r2 != null) {
      final v1 = Tuple2(r1.$0, r2.$0);
      return Tuple1(v1);
    }
  }

  state.pos = pos;
}