/**
* Returns the new target type, or {@code null} if conversion is not necessary.
*
* @param curr old item
* @param it new item
* @return result (or {@code null})
* @throws QueryException query exception
*/
private AtomType numType(final Item curr, final Item it) throws QueryException {
final Type ti = it.type;
if (ti.isUntyped()) return DBL;
final Type tc = curr.type;
if (!(it instanceof ANum)) throw EXPTYPE_X_X_X.get(info, tc, ti, it);
return tc == ti ? null : tc == DBL || ti == DBL ? DBL : tc == FLT || ti == FLT ? FLT : null;
}
/**
* Checks if the specified item is a QName. Returns the item or throws an exception.
*
* @param it item
* @param empty allow empty result
* @return QNm item
* @throws QueryException query exception
*/
protected final QNm toQNm(final Item it, final boolean empty) throws QueryException {
if (empty && it == null) return null;
final Type ip = checkNoEmpty(it, AtomType.QNM).type;
if (ip == AtomType.QNM) return (QNm) it;
if (ip.isUntyped()) throw NSSENS_X_X.get(info, ip, AtomType.QNM);
throw castError(it, AtomType.QNM, info);
}
/**
* Checks if the specified item is a number. Returns a token representation or throws an
* exception.
*
* @param it item to be checked
* @return number
* @throws QueryException query exception
*/
protected final long toLong(final Item it) throws QueryException {
final Type ip = checkNoEmpty(it, AtomType.ITR).type;
if (ip.instanceOf(AtomType.ITR) || ip.isUntyped()) return it.itr(info);
throw castError(it, AtomType.ITR, info);
}
/**
* 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);
}