/**
* 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;
}
/**
* 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;
}