Lucene.Net.Join.ToParentBlockJoinCollector.AccumulateGroups C# (CSharp) Method

        private TopGroups<int> AccumulateGroups(int slot, int offset, int maxDocsPerGroup, int withinGroupOffset, Sort withinGroupSort, bool fillSortFields)
        {
            var groups = new GroupDocs<int>[sortedGroups.Length - offset];
            var fakeScorer = new FakeScorer();

            int totalGroupedHitCount = 0;
            //System.out.println("slot=" + slot);

            for (int groupIdx = offset; groupIdx < sortedGroups.Length; groupIdx++)
            {
                OneGroup og = sortedGroups[groupIdx];
                int numChildDocs;
                if (slot == -1 || slot >= og.counts.Length)
                {
                    numChildDocs = 0;
                }
                else
                {
                    numChildDocs = og.counts[slot];
                }

                // Number of documents in group should be bounded to prevent redundant memory allocation
                int numDocsInGroup = Math.Max(1, Math.Min(numChildDocs, maxDocsPerGroup));
                //System.out.println("parent doc=" + og.doc + " numChildDocs=" + numChildDocs + " maxDocsPG=" + maxDocsPerGroup);

                // At this point we hold all docs w/ in each group, unsorted; we now sort them:
                Collector collector;
                if (withinGroupSort == null)
                {
                    //System.out.println("sort by score");
                    // Sort by score
                    if (!trackScores)
                    {
                        throw new ArgumentException("cannot sort by relevance within group: trackScores=false");
                    }
                    collector = TopScoreDocCollector.Create(numDocsInGroup, true);
                }
                else
                {
                    // Sort by fields
                    collector = TopFieldCollector.Create(withinGroupSort, numDocsInGroup, fillSortFields, trackScores, trackMaxScore, true);
                }

                collector.Scorer = fakeScorer;
                collector.NextReader = og.readerContext;
                for (int docIdx = 0; docIdx < numChildDocs; docIdx++)
                {
                    //System.out.println("docIDX=" + docIDX + " vs " + og.docs[slot].length);
                    int doc = og.docs[slot][docIdx];
                    fakeScorer.doc = doc;
                    if (trackScores)
                    {
                        fakeScorer._score = og.scores[slot][docIdx];
                    }
                    collector.Collect(doc);
                }
                totalGroupedHitCount += numChildDocs;

                object[] groupSortValues;

                if (fillSortFields)
                {
                    groupSortValues = new object[comparators.Length];
                    for (int sortFieldIdx = 0; sortFieldIdx < comparators.Length; sortFieldIdx++)
                    {
                        groupSortValues[sortFieldIdx] = comparators[sortFieldIdx].Value(og.Slot);
                    }
                }
                else
                {
                    groupSortValues = null;
                }

                TopDocs topDocs;
                if (withinGroupSort == null)
                {
                    var tempCollector = (TopScoreDocCollector) collector;
                    topDocs = tempCollector.TopDocs(withinGroupOffset, numDocsInGroup);
                }
                else
                {
                    var tempCollector = (TopFieldCollector) collector;
                    topDocs = tempCollector.TopDocs(withinGroupOffset, numDocsInGroup);
                }
                
                groups[groupIdx - offset] = new GroupDocs<int>(og.Score, topDocs.MaxScore, numChildDocs, topDocs.ScoreDocs, og.Doc, groupSortValues);
            }

            return new TopGroups<int>(new TopGroups<int>(sort.GetSort(), withinGroupSort == null ? null : withinGroupSort.GetSort(), 0, totalGroupedHitCount, groups, maxScore), totalHitCount);
        }