org.apache.lucene.search.grouping.SecondPassGroupingCollector Maven / Gradle / Ivy
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* 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.Collection;
import java.util.Objects;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.Scorable;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.SimpleCollector;
/**
* SecondPassGroupingCollector runs over an already collected set of groups, further applying a
* {@link GroupReducer} to each group
*
* @see TopGroupsCollector
* @see DistinctValuesCollector
* @lucene.experimental
*/
public class SecondPassGroupingCollector extends SimpleCollector {
protected final GroupSelector groupSelector;
protected final Collection> groups;
protected final GroupReducer groupReducer;
protected int totalHitCount;
protected int totalGroupedHitCount;
/**
* Create a new SecondPassGroupingCollector
*
* @param groupSelector the GroupSelector that defines groups for this search
* @param groups the groups to collect documents for
* @param reducer the reducer to apply to each group
*/
public SecondPassGroupingCollector(
GroupSelector groupSelector,
Collection> groups,
GroupReducer reducer) {
// System.out.println("SP init");
if (groups.isEmpty()) {
throw new IllegalArgumentException("no groups to collect (groups is empty)");
}
this.groupSelector = Objects.requireNonNull(groupSelector);
this.groupSelector.setGroups(groups);
this.groups = Objects.requireNonNull(groups);
this.groupReducer = reducer;
reducer.setGroups(groups);
}
/**
* @return the GroupSelector used in this collector
*/
public GroupSelector getGroupSelector() {
return groupSelector;
}
@Override
public ScoreMode scoreMode() {
return groupReducer.needsScores() ? ScoreMode.COMPLETE : ScoreMode.COMPLETE_NO_SCORES;
}
@Override
public void setScorer(Scorable scorer) throws IOException {
groupSelector.setScorer(scorer);
groupReducer.setScorer(scorer);
}
@Override
public void collect(int doc) throws IOException {
totalHitCount++;
if (groupSelector.advanceTo(doc) == GroupSelector.State.SKIP) {
return;
}
totalGroupedHitCount++;
T value = groupSelector.currentValue();
groupReducer.collect(value, doc);
}
@Override
protected void doSetNextReader(LeafReaderContext readerContext) throws IOException {
groupReducer.setNextReader(readerContext);
groupSelector.setNextReader(readerContext);
}
}