conditionParameterIndex method
Implementation
Parser<ConditionParameter> conditionParameterIndex() =>
(char('?') & (char('#') & digit().star().flatten())).trim().map((l) {
var idxPart = l[1] as List;
var idxStr = idxPart[1] as String;
var idx = idxStr.isNotEmpty ? int.parse(idxStr) : -1;
return ConditionParameter.index(idx);
});