parse method
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<E>? parse(ParseState state) {
final r1 = p.parse(state);
if (r1 != null) {
return r1;
}
state.fail(_err, state.pos);
}