ConjunctionDISI nextDoc can return immediately when NO_MORE_DOCS

[YouPeng Yang]

Hi
  I am reading the code of class ConjunctionDISI .and about the method
nextDoc ,  Suppose that the sub-disi is emtpy in the lead1.lead2,should
there be that it can return immediately when the input doc==NO_MORE_DOCS?


private int doNext(int doc) throws IOException {
advanceHead:
for (; ; ) {
assert doc == lead1.docID();
//assumpt doc==NO_MORE_DOCS ,it return
if(doc==NO_MORE_DOCS){
return NO_MORE_DOCS;
}
// find agreement between the two iterators with the lower costs
// we special case them because they do not need the
// 'other.docID() < doc' check that the 'others' iterators need
final int next2 = lead2.advance(doc);
if (next2 != doc) {
doc = lead1.advance(next2);
if(doc==NO_MORE_DOCS){
return NO_MORE_DOCS;
}
if (next2 != doc) {
continue;
}
}
..left omited...
}