/**
* 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 double. Returns the double or throws an exception.
*
* @param it item
* @return double
* @throws QueryException query exception
*/
protected final double toDouble(final Item it) throws QueryException {
if (checkNoEmpty(it, AtomType.DBL).type.isNumberOrUntyped()) return it.dbl(info);
throw numberError(this, it);
}
/**
* Checks if the specified, non-empty item is a double. Returns the double or throws an exception.
*
* @param it item to be checked
* @return number
* @throws QueryException query exception
*/
private ANum toNumber(final Item it) throws QueryException {
if (it.type.isUntyped()) return Dbl.get(it.dbl(info));
if (it instanceof ANum) return (ANum) it;
throw numberError(this, it);
}
@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;
}