/**
* 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);
}
/**
* Returns a minimum or maximum item.
*
* @param cmp comparator
* @param qc query context
* @return resulting item
* @throws QueryException query exception
*/
Item minmax(final OpV cmp, final QueryContext qc) throws QueryException {
final Collation coll = toCollation(1, qc);
final Iter iter = exprs[0].atomIter(qc, info);
Item curr = iter.next();
if (curr == null) return null;
// check if first item is comparable
cmp.eval(curr, curr, coll, sc, info);
// strings
if (curr instanceof AStr) {
for (Item it; (it = iter.next()) != null; ) {
if (!(it instanceof AStr)) throw EXPTYPE_X_X_X.get(info, curr.type, it.type, it);
final Type rt = curr.type, ri = it.type;
if (cmp.eval(curr, it, coll, sc, info)) curr = it;
if (rt != ri && curr.type == URI) curr = STR.cast(curr, qc, sc, info);
}
return curr;
}
// dates, durations, booleans, binary values
if (curr instanceof ADate || curr instanceof Dur || curr instanceof Bin || curr.type == BLN) {
for (Item it; (it = iter.next()) != null; ) {
if (curr.type != it.type) throw EXPTYPE_X_X_X.get(info, curr.type, it.type, it);
if (cmp.eval(curr, it, coll, sc, info)) curr = it;
}
return curr;
}
// numbers
if (curr.type.isUntyped()) curr = DBL.cast(curr, qc, sc, info);
for (Item it; (it = iter.next()) != null; ) {
final Type type = numType(curr, it);
if (cmp.eval(curr, it, coll, sc, info) || Double.isNaN(it.dbl(info))) curr = it;
if (type != null) curr = (Item) type.cast(curr, qc, sc, info);
}
return curr;
}
/**
* 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);
}
/**
* Checks if the specified non-empty item is a string. Returns its value as token or throws an
* exception.
*
* @param it item to be checked
* @return token
* @throws QueryException query exception
*/
protected final byte[] toToken(final Item it) throws QueryException {
final Type ip = it.type;
if (ip.isStringOrUntyped()) return it.string(info);
throw it instanceof FItem ? FIATOM_X.get(info, it.type) : castError(it, AtomType.STR, info);
}