@Override
public Value value(final QueryContext qc) throws QueryException {
final FItem getKey = checkArity(exprs[1], 1, qc);
final long k = Math.min(toLong(exprs[2], qc), Integer.MAX_VALUE);
if (k < 1) return Empty.SEQ;
final Iter iter = exprs[0].iter(qc);
final MinHeap<Item, Item> heap =
new MinHeap<>(
new Comparator<Item>() {
@Override
public int compare(final Item it1, final Item it2) {
try {
return OpV.LT.eval(it1, it2, sc.collation, sc, info) ? -1 : 1;
} catch (final QueryException qe) {
throw new QueryRTException(qe);
}
}
});
try {
for (Item it; (it = iter.next()) != null; ) {
heap.insert(checkNoEmpty(getKey.invokeItem(qc, info, it)), it);
if (heap.size() > k) heap.removeMin();
}
} catch (final QueryRTException ex) {
throw ex.getCause();
}
final ValueBuilder vb = new ValueBuilder();
while (!heap.isEmpty()) vb.addFront(heap.removeMin());
return vb.value();
}
@Override
FItem evalFunc(final QueryContext ctx) throws QueryException {
final int ar = expr.length - 1;
final Item it = checkItem(expr[ar], ctx);
if (!(it instanceof FItem)) throw INVFUNCITEM.get(info, it.type);
final FItem fit = (FItem) it;
if (fit.arity() != ar) throw INVARITY.get(info, fit, ar);
if (!sc.mixUpdates && updating != fit.annotations().contains(Ann.Q_UPDATING))
throw (updating ? UPFUNCNOTUP : UPFUNCUP).get(info);
return fit;
}
/**
* Performs the test function.
*
* @param ctx query context
* @return resulting value
* @throws QueryException query exception
*/
private Item test(final QueryContext ctx) throws QueryException {
final Unit unit = new Unit(ctx, info);
if (expr.length == 0) return unit.test(sc);
final ArrayList<StaticFunc> funcs = new ArrayList<>();
final Iter ir = ctx.iter(expr[0]);
for (Item it; (it = ir.next()) != null; ) {
final FItem fi = checkFunc(it, ctx);
if (fi.funcName() != null) {
final StaticFunc sf = ctx.funcs.get(fi.funcName(), fi.arity(), null, true);
if (sf != null) funcs.add(sf);
}
}
return unit.test(sc, funcs);
}