lucene/grouping/src/java/org/apache/lucene/search/grouping/TermGroupFacetCollector.java - lucene-solr - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package org.apache.lucene.search.grouping;

 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;

 import org.apache.lucene.index.DocValues;
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.index.SortedDocValues;
 import org.apache.lucene.index.SortedSetDocValues;
 import org.apache.lucene.index.TermsEnum;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.BytesRefBuilder;
 import org.apache.lucene.util.SentinelIntSet;
 import org.apache.lucene.util.UnicodeUtil;

 /**
  * An implementation of {@link GroupFacetCollector} that computes grouped facets based on the indexed terms
  * from DocValues.
  *
  * @lucene.experimental
  */
 public abstract class TermGroupFacetCollector extends GroupFacetCollector {

   final List<GroupedFacetHit> groupedFacetHits;
   final SentinelIntSet segmentGroupedFacetHits;

   SortedDocValues groupFieldTermsIndex;

   /**
    * Factory method for creating the right implementation based on the fact whether the facet field contains
    * multiple tokens per documents.
    *
    * @param groupField The group field
    * @param facetField The facet field
    * @param facetFieldMultivalued Whether the facet field has multiple tokens per document
    * @param facetPrefix The facet prefix a facet entry should start with to be included.
    * @param initialSize The initial allocation size of the internal int set and group facet list which should roughly
    *                    match the total number of expected unique groups. Be aware that the heap usage is
    *                    4 bytes * initialSize.
    * @return <code>TermGroupFacetCollector</code> implementation
    */
   public static TermGroupFacetCollector createTermGroupFacetCollector(String groupField,
                                                                       String facetField,
                                                                       boolean facetFieldMultivalued,
                                                                       BytesRef facetPrefix,
                                                                       int initialSize) {
     if (facetFieldMultivalued) {
       return new MV(groupField, facetField, facetPrefix, initialSize);
     } else {
       return new SV(groupField, facetField, facetPrefix, initialSize);
     }
   }

   TermGroupFacetCollector(String groupField, String facetField, BytesRef facetPrefix, int initialSize) {
     super(groupField, facetField, facetPrefix);
     groupedFacetHits = new ArrayList<>(initialSize);
     segmentGroupedFacetHits = new SentinelIntSet(initialSize, Integer.MIN_VALUE);
   }

   // Implementation for single valued facet fields.
   static class SV extends TermGroupFacetCollector {

     private SortedDocValues facetFieldTermsIndex;

     SV(String groupField, String facetField, BytesRef facetPrefix, int initialSize) {
       super(groupField, facetField, facetPrefix, initialSize);
     }

     @Override
     public void collect(int doc) throws IOException {
       if (doc > facetFieldTermsIndex.docID()) {
         facetFieldTermsIndex.advance(doc);
       }

       int facetOrd;
       if (doc == facetFieldTermsIndex.docID()) {
         facetOrd = facetFieldTermsIndex.ordValue();
       } else {
         facetOrd = -1;
       }

       if (facetOrd < startFacetOrd || facetOrd >= endFacetOrd) {
         return;
       }

       if (doc > groupFieldTermsIndex.docID()) {
         groupFieldTermsIndex.advance(doc);
       }

       int groupOrd;
       if (doc == groupFieldTermsIndex.docID()) {
         groupOrd = groupFieldTermsIndex.ordValue();
       } else {
         groupOrd = -1;
       }
       int segmentGroupedFacetsIndex = groupOrd * (facetFieldTermsIndex.getValueCount()+1) + facetOrd;
       if (segmentGroupedFacetHits.exists(segmentGroupedFacetsIndex)) {
         return;
       }

       segmentTotalCount++;
       segmentFacetCounts[facetOrd+1]++;

       segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);

       BytesRef groupKey;
       if (groupOrd == -1) {
         groupKey = null;
       } else {
         groupKey = BytesRef.deepCopyOf(groupFieldTermsIndex.lookupOrd(groupOrd));
       }

       BytesRef facetKey;
       if (facetOrd == -1) {
         facetKey = null;
       } else {
         facetKey = BytesRef.deepCopyOf(facetFieldTermsIndex.lookupOrd(facetOrd));
       }

       groupedFacetHits.add(new GroupedFacetHit(groupKey, facetKey));
     }

     @Override
     protected void doSetNextReader(LeafReaderContext context) throws IOException {
       if (segmentFacetCounts != null) {
         segmentResults.add(createSegmentResult());
       }

       groupFieldTermsIndex = DocValues.getSorted(context.reader(), groupField);
       facetFieldTermsIndex = DocValues.getSorted(context.reader(), facetField);

       // 1+ to allow for the -1 "not set":
       segmentFacetCounts = new int[facetFieldTermsIndex.getValueCount()+1];
       segmentTotalCount = 0;

       segmentGroupedFacetHits.clear();
       for (GroupedFacetHit groupedFacetHit : groupedFacetHits) {
         int facetOrd = groupedFacetHit.facetValue == null ? -1 : facetFieldTermsIndex.lookupTerm(groupedFacetHit.facetValue);
         if (groupedFacetHit.facetValue != null && facetOrd < 0) {
           continue;
         }

         int groupOrd = groupedFacetHit.groupValue == null ? -1 : groupFieldTermsIndex.lookupTerm(groupedFacetHit.groupValue);
         if (groupedFacetHit.groupValue != null && groupOrd < 0) {
           continue;
         }

         int segmentGroupedFacetsIndex = groupOrd * (facetFieldTermsIndex.getValueCount()+1) + facetOrd;
         segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);
       }

       if (facetPrefix != null) {
         startFacetOrd = facetFieldTermsIndex.lookupTerm(facetPrefix);
         if (startFacetOrd < 0) {
           // Points to the ord one higher than facetPrefix
           startFacetOrd = -startFacetOrd - 1;
         }
         BytesRefBuilder facetEndPrefix = new BytesRefBuilder();
         facetEndPrefix.append(facetPrefix);
         facetEndPrefix.append(UnicodeUtil.BIG_TERM);
         endFacetOrd = facetFieldTermsIndex.lookupTerm(facetEndPrefix.get());
         assert endFacetOrd < 0;
         endFacetOrd = -endFacetOrd - 1; // Points to the ord one higher than facetEndPrefix
       } else {
         startFacetOrd = -1;
         endFacetOrd = facetFieldTermsIndex.getValueCount();
       }
     }

     @Override
     protected SegmentResult createSegmentResult() throws IOException {
       return new SegmentResult(segmentFacetCounts, segmentTotalCount, facetFieldTermsIndex.termsEnum(), startFacetOrd, endFacetOrd);
     }

     private static class SegmentResult extends GroupFacetCollector.SegmentResult {

       final TermsEnum tenum;

       SegmentResult(int[] counts, int total, TermsEnum tenum, int startFacetOrd, int endFacetOrd) throws IOException {
         super(counts, total - counts[0], counts[0], endFacetOrd+1);
         this.tenum = tenum;
         this.mergePos = startFacetOrd == -1 ? 1 : startFacetOrd+1;
         if (mergePos < maxTermPos) {
           assert tenum != null;
           tenum.seekExact(startFacetOrd == -1 ? 0 : startFacetOrd);
           mergeTerm = tenum.term();
         }
       }

       @Override
       protected void nextTerm() throws IOException {
         mergeTerm = tenum.next();
       }
     }
   }

   // Implementation for multi valued facet fields.
   static class MV extends TermGroupFacetCollector {

     private SortedSetDocValues facetFieldDocTermOrds;
     private TermsEnum facetOrdTermsEnum;
     private int facetFieldNumTerms;

     MV(String groupField, String facetField, BytesRef facetPrefix, int initialSize) {
       super(groupField, facetField, facetPrefix, initialSize);
     }

     @Override
     public void collect(int doc) throws IOException {
       if (doc > groupFieldTermsIndex.docID()) {
         groupFieldTermsIndex.advance(doc);
       }

       int groupOrd;
       if (doc == groupFieldTermsIndex.docID()) {
         groupOrd = groupFieldTermsIndex.ordValue();
       } else {
         groupOrd = -1;
       }

       if (facetFieldNumTerms == 0) {
         int segmentGroupedFacetsIndex = groupOrd * (facetFieldNumTerms + 1);
         if (facetPrefix != null || segmentGroupedFacetHits.exists(segmentGroupedFacetsIndex)) {
           return;
         }

         segmentTotalCount++;
         segmentFacetCounts[facetFieldNumTerms]++;

         segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);
         BytesRef groupKey;
         if (groupOrd == -1) {
           groupKey = null;
         } else {
           groupKey = BytesRef.deepCopyOf(groupFieldTermsIndex.lookupOrd(groupOrd));
         }
         groupedFacetHits.add(new GroupedFacetHit(groupKey, null));
         return;
       }

       if (doc > facetFieldDocTermOrds.docID()) {
         facetFieldDocTermOrds.advance(doc);
       }
       boolean empty = true;
       if (doc == facetFieldDocTermOrds.docID()) {
         long ord;
         while ((ord = facetFieldDocTermOrds.nextOrd()) != SortedSetDocValues.NO_MORE_ORDS) {
           process(groupOrd, (int) ord);
           empty = false;
         }
       }

       if (empty) {
         process(groupOrd, facetFieldNumTerms); // this facet ord is reserved for docs not containing facet field.
       }
     }

     private void process(int groupOrd, int facetOrd) throws IOException {
       if (facetOrd < startFacetOrd || facetOrd >= endFacetOrd) {
         return;
       }

       int segmentGroupedFacetsIndex = groupOrd * (facetFieldNumTerms + 1) + facetOrd;
       if (segmentGroupedFacetHits.exists(segmentGroupedFacetsIndex)) {
         return;
       }

       segmentTotalCount++;
       segmentFacetCounts[facetOrd]++;

       segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);

       BytesRef groupKey;
       if (groupOrd == -1) {
         groupKey = null;
       } else {
         groupKey = BytesRef.deepCopyOf(groupFieldTermsIndex.lookupOrd(groupOrd));
       }

       final BytesRef facetValue;
       if (facetOrd == facetFieldNumTerms) {
         facetValue = null;
       } else {
         facetValue = BytesRef.deepCopyOf(facetFieldDocTermOrds.lookupOrd(facetOrd));
       }
       groupedFacetHits.add(new GroupedFacetHit(groupKey, facetValue));
     }

     @Override
     protected void doSetNextReader(LeafReaderContext context) throws IOException {
       if (segmentFacetCounts != null) {
         segmentResults.add(createSegmentResult());
       }

       groupFieldTermsIndex = DocValues.getSorted(context.reader(), groupField);
       facetFieldDocTermOrds = DocValues.getSortedSet(context.reader(), facetField);
       facetFieldNumTerms = (int) facetFieldDocTermOrds.getValueCount();
       if (facetFieldNumTerms == 0) {
         facetOrdTermsEnum = null;
       } else {
         facetOrdTermsEnum = facetFieldDocTermOrds.termsEnum();
       }
       // [facetFieldNumTerms() + 1] for all possible facet values and docs not containing facet field
       segmentFacetCounts = new int[facetFieldNumTerms + 1];
       segmentTotalCount = 0;

       segmentGroupedFacetHits.clear();
       for (GroupedFacetHit groupedFacetHit : groupedFacetHits) {
         int groupOrd = groupedFacetHit.groupValue == null ? -1 : groupFieldTermsIndex.lookupTerm(groupedFacetHit.groupValue);
         if (groupedFacetHit.groupValue != null && groupOrd < 0) {
           continue;
         }

         int facetOrd;
         if (groupedFacetHit.facetValue != null) {
           if (facetOrdTermsEnum == null || !facetOrdTermsEnum.seekExact(groupedFacetHit.facetValue)) {
             continue;
           }
           facetOrd = (int) facetOrdTermsEnum.ord();
         } else {
           facetOrd = facetFieldNumTerms;
         }

         // (facetFieldDocTermOrds.numTerms() + 1) for all possible facet values and docs not containing facet field
         int segmentGroupedFacetsIndex = groupOrd * (facetFieldNumTerms + 1) + facetOrd;
         segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);
       }

       if (facetPrefix != null) {
         TermsEnum.SeekStatus seekStatus;
         if (facetOrdTermsEnum != null) {
           seekStatus = facetOrdTermsEnum.seekCeil(facetPrefix);
         } else {
           seekStatus = TermsEnum.SeekStatus.END;
         }

         if (seekStatus != TermsEnum.SeekStatus.END) {
           startFacetOrd = (int) facetOrdTermsEnum.ord();
         } else {
           startFacetOrd = 0;
           endFacetOrd = 0;
           return;
         }

         BytesRefBuilder facetEndPrefix = new BytesRefBuilder();
         facetEndPrefix.append(facetPrefix);
         facetEndPrefix.append(UnicodeUtil.BIG_TERM);
         seekStatus = facetOrdTermsEnum.seekCeil(facetEndPrefix.get());
         if (seekStatus != TermsEnum.SeekStatus.END) {
           endFacetOrd = (int) facetOrdTermsEnum.ord();
         } else {
           endFacetOrd = facetFieldNumTerms; // Don't include null...
         }
       } else {
         startFacetOrd = 0;
         endFacetOrd = facetFieldNumTerms + 1;
       }
     }

     @Override
     protected SegmentResult createSegmentResult() throws IOException {
       return new SegmentResult(segmentFacetCounts, segmentTotalCount, facetFieldNumTerms, facetOrdTermsEnum, startFacetOrd, endFacetOrd);
     }

     private static class SegmentResult extends GroupFacetCollector.SegmentResult {

       final TermsEnum tenum;

       SegmentResult(int[] counts, int total, int missingCountIndex, TermsEnum tenum, int startFacetOrd, int endFacetOrd) throws IOException {
         super(counts, total - counts[missingCountIndex], counts[missingCountIndex],
             endFacetOrd == missingCountIndex + 1 ?  missingCountIndex : endFacetOrd);
         this.tenum = tenum;
         this.mergePos = startFacetOrd;
         if (tenum != null) {
           tenum.seekExact(mergePos);
           mergeTerm = tenum.term();
         }
       }

       @Override
       protected void nextTerm() throws IOException {
         mergeTerm = tenum.next();
       }
     }
   }

   private static class GroupedFacetHit {

     final BytesRef groupValue;
     final BytesRef facetValue;

     GroupedFacetHit(BytesRef groupValue, BytesRef facetValue) {
       this.groupValue = groupValue;
       this.facetValue = facetValue;
     }
   }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package org.apache.lucene.search.grouping;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.List;

	import org.apache.lucene.index.DocValues;
	import org.apache.lucene.index.LeafReaderContext;
	import org.apache.lucene.index.SortedDocValues;
	import org.apache.lucene.index.SortedSetDocValues;
	import org.apache.lucene.index.TermsEnum;
	import org.apache.lucene.util.BytesRef;
	import org.apache.lucene.util.BytesRefBuilder;
	import org.apache.lucene.util.SentinelIntSet;
	import org.apache.lucene.util.UnicodeUtil;

	/**
	* An implementation of {@link GroupFacetCollector} that computes grouped facets based on the indexed terms
	* from DocValues.
	*
	* @lucene.experimental
	*/
	public abstract class TermGroupFacetCollector extends GroupFacetCollector {

	final List<GroupedFacetHit> groupedFacetHits;
	final SentinelIntSet segmentGroupedFacetHits;

	SortedDocValues groupFieldTermsIndex;

	/**
	* Factory method for creating the right implementation based on the fact whether the facet field contains
	* multiple tokens per documents.
	*
	* @param groupField The group field
	* @param facetField The facet field
	* @param facetFieldMultivalued Whether the facet field has multiple tokens per document
	* @param facetPrefix The facet prefix a facet entry should start with to be included.
	* @param initialSize The initial allocation size of the internal int set and group facet list which should roughly
	* match the total number of expected unique groups. Be aware that the heap usage is
	* 4 bytes * initialSize.
	* @return <code>TermGroupFacetCollector</code> implementation
	*/
	public static TermGroupFacetCollector createTermGroupFacetCollector(String groupField,
	String facetField,
	boolean facetFieldMultivalued,
	BytesRef facetPrefix,
	int initialSize) {
	if (facetFieldMultivalued) {
	return new MV(groupField, facetField, facetPrefix, initialSize);
	} else {
	return new SV(groupField, facetField, facetPrefix, initialSize);
	}
	}

	TermGroupFacetCollector(String groupField, String facetField, BytesRef facetPrefix, int initialSize) {
	super(groupField, facetField, facetPrefix);
	groupedFacetHits = new ArrayList<>(initialSize);
	segmentGroupedFacetHits = new SentinelIntSet(initialSize, Integer.MIN_VALUE);
	}

	// Implementation for single valued facet fields.
	static class SV extends TermGroupFacetCollector {

	private SortedDocValues facetFieldTermsIndex;

	SV(String groupField, String facetField, BytesRef facetPrefix, int initialSize) {
	super(groupField, facetField, facetPrefix, initialSize);
	}

	@Override
	public void collect(int doc) throws IOException {
	if (doc > facetFieldTermsIndex.docID()) {
	facetFieldTermsIndex.advance(doc);
	}

	int facetOrd;
	if (doc == facetFieldTermsIndex.docID()) {
	facetOrd = facetFieldTermsIndex.ordValue();
	} else {
	facetOrd = -1;
	}

	if (facetOrd < startFacetOrd \|\| facetOrd >= endFacetOrd) {
	return;
	}

	if (doc > groupFieldTermsIndex.docID()) {
	groupFieldTermsIndex.advance(doc);
	}

	int groupOrd;
	if (doc == groupFieldTermsIndex.docID()) {
	groupOrd = groupFieldTermsIndex.ordValue();
	} else {
	groupOrd = -1;
	}
	int segmentGroupedFacetsIndex = groupOrd * (facetFieldTermsIndex.getValueCount()+1) + facetOrd;
	if (segmentGroupedFacetHits.exists(segmentGroupedFacetsIndex)) {
	return;
	}

	segmentTotalCount++;
	segmentFacetCounts[facetOrd+1]++;

	segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);

	BytesRef groupKey;
	if (groupOrd == -1) {
	groupKey = null;
	} else {
	groupKey = BytesRef.deepCopyOf(groupFieldTermsIndex.lookupOrd(groupOrd));
	}

	BytesRef facetKey;
	if (facetOrd == -1) {
	facetKey = null;
	} else {
	facetKey = BytesRef.deepCopyOf(facetFieldTermsIndex.lookupOrd(facetOrd));
	}

	groupedFacetHits.add(new GroupedFacetHit(groupKey, facetKey));
	}

	@Override
	protected void doSetNextReader(LeafReaderContext context) throws IOException {
	if (segmentFacetCounts != null) {
	segmentResults.add(createSegmentResult());
	}

	groupFieldTermsIndex = DocValues.getSorted(context.reader(), groupField);
	facetFieldTermsIndex = DocValues.getSorted(context.reader(), facetField);

	// 1+ to allow for the -1 "not set":
	segmentFacetCounts = new int[facetFieldTermsIndex.getValueCount()+1];
	segmentTotalCount = 0;

	segmentGroupedFacetHits.clear();
	for (GroupedFacetHit groupedFacetHit : groupedFacetHits) {
	int facetOrd = groupedFacetHit.facetValue == null ? -1 : facetFieldTermsIndex.lookupTerm(groupedFacetHit.facetValue);
	if (groupedFacetHit.facetValue != null && facetOrd < 0) {
	continue;
	}

	int groupOrd = groupedFacetHit.groupValue == null ? -1 : groupFieldTermsIndex.lookupTerm(groupedFacetHit.groupValue);
	if (groupedFacetHit.groupValue != null && groupOrd < 0) {
	continue;
	}

	int segmentGroupedFacetsIndex = groupOrd * (facetFieldTermsIndex.getValueCount()+1) + facetOrd;
	segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);
	}

	if (facetPrefix != null) {
	startFacetOrd = facetFieldTermsIndex.lookupTerm(facetPrefix);
	if (startFacetOrd < 0) {
	// Points to the ord one higher than facetPrefix
	startFacetOrd = -startFacetOrd - 1;
	}
	BytesRefBuilder facetEndPrefix = new BytesRefBuilder();
	facetEndPrefix.append(facetPrefix);
	facetEndPrefix.append(UnicodeUtil.BIG_TERM);
	endFacetOrd = facetFieldTermsIndex.lookupTerm(facetEndPrefix.get());
	assert endFacetOrd < 0;
	endFacetOrd = -endFacetOrd - 1; // Points to the ord one higher than facetEndPrefix
	} else {
	startFacetOrd = -1;
	endFacetOrd = facetFieldTermsIndex.getValueCount();
	}
	}

	@Override
	protected SegmentResult createSegmentResult() throws IOException {
	return new SegmentResult(segmentFacetCounts, segmentTotalCount, facetFieldTermsIndex.termsEnum(), startFacetOrd, endFacetOrd);
	}

	private static class SegmentResult extends GroupFacetCollector.SegmentResult {

	final TermsEnum tenum;

	SegmentResult(int[] counts, int total, TermsEnum tenum, int startFacetOrd, int endFacetOrd) throws IOException {
	super(counts, total - counts[0], counts[0], endFacetOrd+1);
	this.tenum = tenum;
	this.mergePos = startFacetOrd == -1 ? 1 : startFacetOrd+1;
	if (mergePos < maxTermPos) {
	assert tenum != null;
	tenum.seekExact(startFacetOrd == -1 ? 0 : startFacetOrd);
	mergeTerm = tenum.term();
	}
	}

	@Override
	protected void nextTerm() throws IOException {
	mergeTerm = tenum.next();
	}
	}
	}

	// Implementation for multi valued facet fields.
	static class MV extends TermGroupFacetCollector {

	private SortedSetDocValues facetFieldDocTermOrds;
	private TermsEnum facetOrdTermsEnum;
	private int facetFieldNumTerms;

	MV(String groupField, String facetField, BytesRef facetPrefix, int initialSize) {
	super(groupField, facetField, facetPrefix, initialSize);
	}

	@Override
	public void collect(int doc) throws IOException {
	if (doc > groupFieldTermsIndex.docID()) {
	groupFieldTermsIndex.advance(doc);
	}

	int groupOrd;
	if (doc == groupFieldTermsIndex.docID()) {
	groupOrd = groupFieldTermsIndex.ordValue();
	} else {
	groupOrd = -1;
	}

	if (facetFieldNumTerms == 0) {
	int segmentGroupedFacetsIndex = groupOrd * (facetFieldNumTerms + 1);
	if (facetPrefix != null \|\| segmentGroupedFacetHits.exists(segmentGroupedFacetsIndex)) {
	return;
	}

	segmentTotalCount++;
	segmentFacetCounts[facetFieldNumTerms]++;

	segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);
	BytesRef groupKey;
	if (groupOrd == -1) {
	groupKey = null;
	} else {
	groupKey = BytesRef.deepCopyOf(groupFieldTermsIndex.lookupOrd(groupOrd));
	}
	groupedFacetHits.add(new GroupedFacetHit(groupKey, null));
	return;
	}

	if (doc > facetFieldDocTermOrds.docID()) {
	facetFieldDocTermOrds.advance(doc);
	}
	boolean empty = true;
	if (doc == facetFieldDocTermOrds.docID()) {
	long ord;
	while ((ord = facetFieldDocTermOrds.nextOrd()) != SortedSetDocValues.NO_MORE_ORDS) {
	process(groupOrd, (int) ord);
	empty = false;
	}
	}

	if (empty) {
	process(groupOrd, facetFieldNumTerms); // this facet ord is reserved for docs not containing facet field.
	}
	}

	private void process(int groupOrd, int facetOrd) throws IOException {
	if (facetOrd < startFacetOrd \|\| facetOrd >= endFacetOrd) {
	return;
	}

	int segmentGroupedFacetsIndex = groupOrd * (facetFieldNumTerms + 1) + facetOrd;
	if (segmentGroupedFacetHits.exists(segmentGroupedFacetsIndex)) {
	return;
	}

	segmentTotalCount++;
	segmentFacetCounts[facetOrd]++;

	segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);

	BytesRef groupKey;
	if (groupOrd == -1) {
	groupKey = null;
	} else {
	groupKey = BytesRef.deepCopyOf(groupFieldTermsIndex.lookupOrd(groupOrd));
	}

	final BytesRef facetValue;
	if (facetOrd == facetFieldNumTerms) {
	facetValue = null;
	} else {
	facetValue = BytesRef.deepCopyOf(facetFieldDocTermOrds.lookupOrd(facetOrd));
	}
	groupedFacetHits.add(new GroupedFacetHit(groupKey, facetValue));
	}

	@Override
	protected void doSetNextReader(LeafReaderContext context) throws IOException {
	if (segmentFacetCounts != null) {
	segmentResults.add(createSegmentResult());
	}

	groupFieldTermsIndex = DocValues.getSorted(context.reader(), groupField);
	facetFieldDocTermOrds = DocValues.getSortedSet(context.reader(), facetField);
	facetFieldNumTerms = (int) facetFieldDocTermOrds.getValueCount();
	if (facetFieldNumTerms == 0) {
	facetOrdTermsEnum = null;
	} else {
	facetOrdTermsEnum = facetFieldDocTermOrds.termsEnum();
	}
	// [facetFieldNumTerms() + 1] for all possible facet values and docs not containing facet field
	segmentFacetCounts = new int[facetFieldNumTerms + 1];
	segmentTotalCount = 0;

	segmentGroupedFacetHits.clear();
	for (GroupedFacetHit groupedFacetHit : groupedFacetHits) {
	int groupOrd = groupedFacetHit.groupValue == null ? -1 : groupFieldTermsIndex.lookupTerm(groupedFacetHit.groupValue);
	if (groupedFacetHit.groupValue != null && groupOrd < 0) {
	continue;
	}

	int facetOrd;
	if (groupedFacetHit.facetValue != null) {
	if (facetOrdTermsEnum == null \|\| !facetOrdTermsEnum.seekExact(groupedFacetHit.facetValue)) {
	continue;
	}
	facetOrd = (int) facetOrdTermsEnum.ord();
	} else {
	facetOrd = facetFieldNumTerms;
	}

	// (facetFieldDocTermOrds.numTerms() + 1) for all possible facet values and docs not containing facet field
	int segmentGroupedFacetsIndex = groupOrd * (facetFieldNumTerms + 1) + facetOrd;
	segmentGroupedFacetHits.put(segmentGroupedFacetsIndex);
	}

	if (facetPrefix != null) {
	TermsEnum.SeekStatus seekStatus;
	if (facetOrdTermsEnum != null) {
	seekStatus = facetOrdTermsEnum.seekCeil(facetPrefix);
	} else {
	seekStatus = TermsEnum.SeekStatus.END;
	}

	if (seekStatus != TermsEnum.SeekStatus.END) {
	startFacetOrd = (int) facetOrdTermsEnum.ord();
	} else {
	startFacetOrd = 0;
	endFacetOrd = 0;
	return;
	}

	BytesRefBuilder facetEndPrefix = new BytesRefBuilder();
	facetEndPrefix.append(facetPrefix);
	facetEndPrefix.append(UnicodeUtil.BIG_TERM);
	seekStatus = facetOrdTermsEnum.seekCeil(facetEndPrefix.get());
	if (seekStatus != TermsEnum.SeekStatus.END) {
	endFacetOrd = (int) facetOrdTermsEnum.ord();
	} else {
	endFacetOrd = facetFieldNumTerms; // Don't include null...
	}
	} else {
	startFacetOrd = 0;
	endFacetOrd = facetFieldNumTerms + 1;
	}
	}

	@Override
	protected SegmentResult createSegmentResult() throws IOException {
	return new SegmentResult(segmentFacetCounts, segmentTotalCount, facetFieldNumTerms, facetOrdTermsEnum, startFacetOrd, endFacetOrd);
	}

	private static class SegmentResult extends GroupFacetCollector.SegmentResult {

	final TermsEnum tenum;

	SegmentResult(int[] counts, int total, int missingCountIndex, TermsEnum tenum, int startFacetOrd, int endFacetOrd) throws IOException {
	super(counts, total - counts[missingCountIndex], counts[missingCountIndex],
	endFacetOrd == missingCountIndex + 1 ? missingCountIndex : endFacetOrd);
	this.tenum = tenum;
	this.mergePos = startFacetOrd;
	if (tenum != null) {
	tenum.seekExact(mergePos);
	mergeTerm = tenum.term();
	}
	}

	@Override
	protected void nextTerm() throws IOException {
	mergeTerm = tenum.next();
	}
	}
	}

	private static class GroupedFacetHit {

	final BytesRef groupValue;
	final BytesRef facetValue;

	GroupedFacetHit(BytesRef groupValue, BytesRef facetValue) {
	this.groupValue = groupValue;
	this.facetValue = facetValue;
	}
	}
	}