@Override
public final int advance(int target) throws IOException {
while (_queue.top() != null && target > _queue.top().docID()) {
DocsAndPositionsEnum postings = _queue.pop();
if (postings.advance(target) != NO_MORE_DOCS) {
_queue.add(postings);
}
}
return nextDoc();
}
@Override
public final int nextDoc() throws IOException {
if (_queue.size() == 0) {
return NO_MORE_DOCS;
}
// TODO: move this init into positions(): if the search
// doesn't need the positions for this doc then don't
// waste CPU merging them:
_posList.clear();
_doc = _queue.top().docID();
// merge sort all positions together
DocsAndPositionsEnum postings;
do {
postings = _queue.top();
final int freq = postings.freq();
for (int i = 0; i < freq; i++) {
_posList.add(postings.nextPosition());
}
if (postings.nextDoc() != NO_MORE_DOCS) {
_queue.updateTop();
} else {
_queue.pop();
}
} while (_queue.size() > 0 && _queue.top().docID() == _doc);
_posList.sort();
_freq = _posList.size();
return _doc;
}