package org.apache.lucene.search.grouping.function;
/*
* 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 org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.queries.function.FunctionValues;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector;
import org.apache.lucene.util.mutable.MutableValue;
import java.io.IOException;
import java.util.Map;
/**
* Concrete implementation of {@link AbstractFirstPassGroupingCollector} that groups based on
* {@link ValueSource} instances.
*
* @lucene.experimental
*/
public class FunctionFirstPassGroupingCollector extends AbstractFirstPassGroupingCollector<MutableValue> {
private final ValueSource groupByVS;
private final Map<?, ?> vsContext;
private FunctionValues.ValueFiller filler;
private MutableValue mval;
/**
* Creates a first pass collector.
*
* @param groupByVS The {@link ValueSource} instance to group by
* @param vsContext The ValueSource context
* @param groupSort The {@link Sort} used to sort the
* groups. The top sorted document within each group
* according to groupSort, determines how that group
* sorts against other groups. This must be non-null,
* ie, if you want to groupSort by relevance use
* Sort.RELEVANCE.
* @param topNGroups How many top groups to keep.
* @throws IOException When I/O related errors occur
*/
public FunctionFirstPassGroupingCollector(ValueSource groupByVS, Map<?, ?> vsContext, Sort groupSort, int topNGroups) throws IOException {
super(groupSort, topNGroups);
this.groupByVS = groupByVS;
this.vsContext = vsContext;
}
@Override
protected MutableValue getDocGroupValue(int doc) {
filler.fillValue(doc);
return mval;
}
@Override
protected MutableValue copyDocGroupValue(MutableValue groupValue, MutableValue reuse) {
if (reuse != null) {
reuse.copy(groupValue);
return reuse;
}
return groupValue.duplicate();
}
@Override
public void setNextReader(AtomicReaderContext readerContext) throws IOException {
super.setNextReader(readerContext);
FunctionValues values = groupByVS.getValues(vsContext, readerContext);
filler = values.getValueFiller();
mval = filler.getValue();
}
}