/*
 * 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
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package org.apache.lucene.search;

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

import org.apache.lucene.index.LeafReaderContext;

A CollectorManager implements which wrap a set of CollectorManager as MultiCollector acts for Collector.
/** * A {@link CollectorManager} implements which wrap a set of {@link CollectorManager} * as {@link MultiCollector} acts for {@link Collector}. */
public class MultiCollectorManager implements CollectorManager<MultiCollectorManager.Collectors, Object[]> { final private CollectorManager<Collector, ?>[] collectorManagers; @SafeVarargs @SuppressWarnings({"varargs", "unchecked"}) public MultiCollectorManager(final CollectorManager<? extends Collector, ?>... collectorManagers) { if (collectorManagers.length < 1) { throw new IllegalArgumentException("There must be at least one collector"); } this.collectorManagers = (CollectorManager[]) collectorManagers; } @Override public Collectors newCollector() throws IOException { return new Collectors(); } @Override public Object[] reduce(Collection<Collectors> reducableCollectors) throws IOException { final int size = reducableCollectors.size(); final Object[] results = new Object[collectorManagers.length]; for (int i = 0; i < collectorManagers.length; i++) { final List<Collector> reducableCollector = new ArrayList<>(size); for (Collectors collectors : reducableCollectors) reducableCollector.add(collectors.collectors[i]); results[i] = collectorManagers[i].reduce(reducableCollector); } return results; } public class Collectors implements Collector { private final Collector[] collectors; private Collectors() throws IOException { collectors = new Collector[collectorManagers.length]; for (int i = 0; i < collectors.length; i++) collectors[i] = collectorManagers[i].newCollector(); } @Override final public LeafCollector getLeafCollector(final LeafReaderContext context) throws IOException { return new LeafCollectors(context); } @Override final public ScoreMode scoreMode() { ScoreMode scoreMode = null; for (Collector collector : collectors) { if (scoreMode == null) { scoreMode = collector.scoreMode(); } else if (scoreMode != collector.scoreMode()) { return ScoreMode.COMPLETE; } } return scoreMode; } public class LeafCollectors implements LeafCollector { private final LeafCollector[] leafCollectors; private LeafCollectors(final LeafReaderContext context) throws IOException { leafCollectors = new LeafCollector[collectors.length]; for (int i = 0; i < collectors.length; i++) leafCollectors[i] = collectors[i].getLeafCollector(context); } @Override final public void setScorer(final Scorable scorer) throws IOException { for (LeafCollector leafCollector : leafCollectors) if (leafCollector != null) leafCollector.setScorer(scorer); } @Override final public void collect(final int doc) throws IOException { for (LeafCollector leafCollector : leafCollectors) if (leafCollector != null) leafCollector.collect(doc); } } } }