/**
* Checks if the specified item is a boolean. Returns the boolean or throws an exception.
*
* @param it item be checked
* @return boolean
* @throws QueryException query exception
*/
protected final boolean toBoolean(final Item it) throws QueryException {
final Type ip = checkNoEmpty(it, AtomType.BLN).type;
if (ip == AtomType.BLN) return it.bool(info);
if (ip.isUntyped()) return Bln.parse(it.string(info), info);
throw castError(it, AtomType.BLN, info);
}
@Override
public final Item test(final QueryContext qc, final InputInfo ii) throws QueryException {
final Item it = ebv(qc, info);
return (it instanceof ANum ? it.dbl(info) == qc.pos : it.bool(info)) ? it : null;
}