protected SegmentTermDocs(SegmentReader parent) 
{
    this.parent = parent;
    this.freqStream = (IndexInput) parent.core.freqStream.clone();
    synchronized (parent) {
      this.deletedDocs = parent.deletedDocs;
    }
    this.skipInterval = parent.core.getTermsReader().getSkipInterval();
    this.maxSkipLevels = parent.core.getTermsReader().getMaxSkipLevels();
}

 public  void close() throws IOException 
{
    freqStream.close();
    if (skipListReader != null)
      skipListReader.close();
}

 public final int doc() 
{
 return doc;
}

 public final int freq() 
{
 return freq;
}

 public boolean next() throws IOException 
{
    while (true) {
      if (count == df)
        return false;
      final int docCode = freqStream.readVInt();
      if (currentFieldOmitTermFreqAndPositions) {
        doc += docCode;
        freq = 1;
      } else {
        doc += docCode  > > > 1;       // shift off low bit
        if ((docCode & 1) != 0)       // if low bit is set
          freq = 1;         // freq is one
        else
          freq = freqStream.readVInt();     // else read freq
      }
      count++;
      if (deletedDocs == null || !deletedDocs.get(doc))
        break;
      skippingDoc();
    }
    return true;
}

 public int read(int[] docs,
    int[] freqs) throws IOException 
{
    final int length = docs.length;
    if (currentFieldOmitTermFreqAndPositions) {
      return readNoTf(docs, freqs, length);
    } else {
      int i = 0;
      while (i <  length && count <  df) {
        // manually inlined call to next() for speed
        final int docCode = freqStream.readVInt();
        doc += docCode  > > > 1;       // shift off low bit
        if ((docCode & 1) != 0)       // if low bit is set
          freq = 1;         // freq is one
        else
          freq = freqStream.readVInt();     // else read freq
        count++;
        if (deletedDocs == null || !deletedDocs.get(doc)) {
          docs[i] = doc;
          freqs[i] = freq;
          ++i;
        }
      }
      return i;
    }
}

Optimized implementation.

 public  void seek(Term term) throws IOException 
{
    TermInfo ti = parent.core.getTermsReader().get(term);
    seek(ti, term);
}

 public  void seek(TermEnum termEnum) throws IOException 
{
    TermInfo ti;
    Term term;
    // use comparison of fieldinfos to verify that termEnum belongs to the same segment as this SegmentTermDocs
    if (termEnum instanceof SegmentTermEnum && ((SegmentTermEnum) termEnum).fieldInfos == parent.core.fieldInfos) {        // optimized case
      SegmentTermEnum segmentTermEnum = ((SegmentTermEnum) termEnum);
      term = segmentTermEnum.term();
      ti = segmentTermEnum.termInfo();
    } else  {                                         // punt case
      term = termEnum.term();
      ti = parent.core.getTermsReader().get(term);
    }
    seek(ti, term);
}

  void seek(TermInfo ti,
    Term term) throws IOException 
{
    count = 0;
    FieldInfo fi = parent.core.fieldInfos.fieldInfo(term.field);
    currentFieldOmitTermFreqAndPositions = (fi != null) ? fi.omitTermFreqAndPositions : false;
    currentFieldStoresPayloads = (fi != null) ? fi.storePayloads : false;
    if (ti == null) {
      df = 0;
    } else {
      df = ti.docFreq;
      doc = 0;
      freqBasePointer = ti.freqPointer;
      proxBasePointer = ti.proxPointer;
      skipPointer = freqBasePointer + ti.skipOffset;
      freqStream.seek(freqBasePointer);
      haveSkipped = false;
    }
}

 protected  void skipProx(long proxPointer,
    int payloadLength) throws IOException 
{

}

Overridden by SegmentTermPositions to skip in prox stream.

 public boolean skipTo(int target) throws IOException 
{
    if (df  >= skipInterval) {                      // optimized case
      if (skipListReader == null)
        skipListReader = new DefaultSkipListReader((IndexInput) freqStream.clone(), maxSkipLevels, skipInterval); // lazily clone
      if (!haveSkipped) {                          // lazily initialize skip stream
        skipListReader.init(skipPointer, freqBasePointer, proxBasePointer, df, currentFieldStoresPayloads);
        haveSkipped = true;
      }
      int newCount = skipListReader.skipTo(target); 
      if (newCount  > count) {
        freqStream.seek(skipListReader.getFreqPointer());
        skipProx(skipListReader.getProxPointer(), skipListReader.getPayloadLength());
        doc = skipListReader.getDoc();
        count = newCount;
      }      
    }
    // done skipping, now just scan
    do {
      if (!next())
        return false;
    } while (target  > doc);
    return true;
}

Optimized implementation.

 protected  void skippingDoc() throws IOException 
{

}