@Override
FItem evalFunc(final QueryContext ctx) throws QueryException {
final int ar = expr.length - 1;
final Item it = checkItem(expr[ar], ctx);
if (!(it instanceof FItem)) throw INVFUNCITEM.get(info, it.type);
final FItem fit = (FItem) it;
if (fit.arity() != ar) throw INVARITY.get(info, fit, ar);
if (!sc.mixUpdates && updating != fit.annotations().contains(Ann.Q_UPDATING))
throw (updating ? UPFUNCNOTUP : UPFUNCUP).get(info);
return fit;
}
