/**
* Performs the doc function.
*
* @param qc query context
* @return result
* @throws QueryException query exception
*/
ANode doc(final QueryContext qc) throws QueryException {
final Item it = exprs[0].item(qc, info);
if (it == null) return null;
final byte[] in = toToken(it);
if (!Uri.uri(in).isValid()) throw INVDOC_X.get(info, in);
return qc.resources.doc(new QueryInput(string(in)), sc.baseIO(), info);
}
/**
* Returns a collection.
*
* @param qc query context
* @return collection
* @throws QueryException query exception
*/
Value collection(final QueryContext qc) throws QueryException {
// return default collection
final Item it = exprs.length == 0 ? null : exprs[0].atomItem(qc, info);
if (it == null) return qc.resources.collection(info);
// check if reference is valid
final byte[] in = toToken(it);
if (!Uri.uri(in).isValid()) throw INVCOLL_X.get(info, in);
return qc.resources.collection(new QueryInput(string(in)), sc.baseIO(), info);
}