ReaderData(IndexReader reader) throws IOException {
this.reader = reader;
long minUID = Long.MAX_VALUE;
long maxUID = Long.MIN_VALUE;
uidMap = new Long2IntRBTreeMap();
uidMap.defaultReturnValue(-1);
int maxDoc = reader.maxDoc();
if (maxDoc == 0) {
_minUID = Long.MIN_VALUE;
_maxUID = Long.MIN_VALUE;