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Lucene example source code file (TermSecondPassGroupingCollector.java)

This example Lucene source code file (TermSecondPassGroupingCollector.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

abstractsecondpassgroupingcollector, collection, io, ioexception, ioexception, override, searchgroupdocs, searchgroupdocs, sentinelintset, sort, sort, string, suppresswarnings, termsecondpassgroupingcollector, termsecondpassgroupingcollector, util

The Lucene TermSecondPassGroupingCollector.java source code

package org.apache.lucene.search.grouping;

/**
 * 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.
 */

import java.io.IOException;
import java.util.Collection;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.search.Sort;

/**
 * Concrete implementation of {@link AbstractSecondPassGroupingCollector} that groups based on
 * field values and more specifically uses {@link org.apache.lucene.search.FieldCache.StringIndex}
 * to collect grouped docs.
 *
 * @lucene.experimental
 */
public class TermSecondPassGroupingCollector extends AbstractSecondPassGroupingCollector<String> {

  private final SentinelIntSet ordSet;
  private FieldCache.StringIndex index;
  private final String groupField;

  @SuppressWarnings("unchecked")
  public TermSecondPassGroupingCollector(String groupField, Collection<SearchGroup groups, Sort groupSort, Sort withinGroupSort,
                                         int maxDocsPerGroup, boolean getScores, boolean getMaxScores, boolean fillSortFields)
      throws IOException {
    super(groups, groupSort, withinGroupSort, maxDocsPerGroup, getScores, getMaxScores, fillSortFields);
    ordSet = new SentinelIntSet(groupMap.size(), -1);
    this.groupField = groupField;
    groupDocs = (SearchGroupDocs<String>[]) new SearchGroupDocs[ordSet.keys.length];
  }

  @Override
  public void setNextReader(IndexReader reader, int docBase) throws IOException {
    super.setNextReader(reader, docBase);
    index = FieldCache.DEFAULT.getStringIndex(reader, groupField);

    // Rebuild ordSet
    ordSet.clear();
    for (SearchGroupDocs<String> group : groupMap.values()) {
//      System.out.println("  group=" + (group.groupValue == null ? "null" : group.groupValue.utf8ToString()));
      int ord = group.groupValue == null ? 0 : index.binarySearchLookup(group.groupValue);
      if (ord >= 0) {
        groupDocs[ordSet.put(ord)] = group;
      }
    }
  }

  @Override
  protected SearchGroupDocs<String> retrieveGroup(int doc) throws IOException {
    int slot = ordSet.find(index.order[doc]);
    if (slot >= 0) {
      return groupDocs[slot];
    }
    return null;
  }
}

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