private BulkScorerAndDoc advance(int min) throws IOException {
assert tail.size() == minShouldMatch - 1;
final HeadPriorityQueue head = this.head;
final TailPriorityQueue tail = this.tail;
BulkScorerAndDoc headTop = head.top();
BulkScorerAndDoc tailTop = tail.top();
while (headTop.next < min) {
if (tailTop == null || headTop.cost <= tailTop.cost) {
headTop.advance(min);
headTop = head.updateTop();
} else {
// swap the top of head and tail
final BulkScorerAndDoc previousHeadTop = headTop;
tailTop.advance(min);
headTop = head.updateTop(tailTop);
tailTop = tail.updateTop(previousHeadTop);
}
}
return headTop;
}
