public InstantiatedTermDocs(InstantiatedIndexReader reader) 
{
    this.reader = reader;
}

 public  void close() 
{

}

Does nothing

 public int doc() 
{
    return currentDocumentInformation.getDocument().getDocumentNumber();
}

 public int freq() 
{
    return currentDocumentInformation.getTermPositions().length;
}

 public boolean next() 
{
    if (currentTerm != null) {
      currentDocumentIndex++;
      if (currentDocumentIndex <  currentTerm.getAssociatedDocuments().length) {
        currentDocumentInformation = currentTerm.getAssociatedDocuments()[currentDocumentIndex];
        if (reader.isDeleted(currentDocumentInformation.getDocument().getDocumentNumber())) {
          return next();
        } else {
          return true;
        }
      } else {
        // mimic SegmentTermDocs
        currentDocumentIndex = currentTerm.getAssociatedDocuments().length -1;
      }
    }
    return false;
}

 public int read(int[] docs,
    int[] freqs) 
{
    int i;
    for (i = 0; i <  docs.length; i++) {
      if (!next()) {
        break;
      }
      docs[i] = doc();
      freqs[i] = freq();
    }
    return i;
}

 public  void seek(Term term) 
{
    currentTerm = reader.getIndex().findTerm(term);
    currentDocumentIndex = -1;
}

 public  void seek(TermEnum termEnum) 
{
    seek(termEnum.term());
}

 public boolean skipTo(int target) 
{
    if (currentTerm == null) {
      return false;
    }
    if (currentDocumentIndex  >= target) {
      return next();
    }
    int startOffset = currentDocumentIndex  >= 0 ? currentDocumentIndex : 0;
    int pos = currentTerm.seekCeilingDocumentInformationIndex(target, startOffset);
    if (pos == -1) {
      // mimic SegmentTermDocs that positions at the last index
      currentDocumentIndex = currentTerm.getAssociatedDocuments().length -1;
      return false;
    }
    currentDocumentInformation = currentTerm.getAssociatedDocuments()[pos];
    currentDocumentIndex = pos;
    if (reader.hasDeletions() && reader.isDeleted(currentDocumentInformation.getDocument().getDocumentNumber())) {
      return next();
    } else {
      return true;
    }
}

Skips entries to the first beyond the current whose document number is greater than or equal to target.

Returns true if there is such an entry.

Behaves as if written:

  boolean skipTo(int target) {
    do {
      if (!next())
	     return false;
    } while (target > doc());
    return true;
  }

This implementation is considerably more efficient than that.