| /* |
| * 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.HashMap; |
| import java.util.Map; |
| |
| import org.apache.lucene.index.LeafReaderContext; |
| import org.apache.lucene.search.Collector; |
| import org.apache.lucene.search.LeafCollector; |
| import org.apache.lucene.search.Scorable; |
| |
| /** |
| * Concrete implementations of this class define what to collect for individual |
| * groups during the second-pass of a grouping search. |
| * |
| * Each group is assigned a Collector returned by {@link #newCollector()}, and |
| * {@link LeafCollector#collect(int)} is called for each document that is in |
| * a group |
| * |
| * @see SecondPassGroupingCollector |
| * |
| * @param <T> the type of the value used for grouping |
| * @param <C> the type of {@link Collector} used to reduce each group |
| */ |
| public abstract class GroupReducer<T, C extends Collector> { |
| |
| private final Map<T, GroupCollector<C>> groups = new HashMap<>(); |
| |
| /** |
| * Define which groups should be reduced. |
| * |
| * Called by {@link SecondPassGroupingCollector} |
| */ |
| public void setGroups(Collection<SearchGroup<T>> groups) { |
| for (SearchGroup<T> group : groups) { |
| this.groups.put(group.groupValue, new GroupCollector<>(newCollector())); |
| } |
| } |
| |
| /** |
| * Whether or not this reducer requires collected documents to be scored |
| */ |
| public abstract boolean needsScores(); |
| |
| /** |
| * Creates a new Collector for each group |
| */ |
| protected abstract C newCollector(); |
| |
| /** |
| * Get the Collector for a given group |
| */ |
| public final C getCollector(T value) { |
| return groups.get(value).collector; |
| } |
| |
| /** |
| * Collect a given document into a given group |
| * @throws IOException on error |
| */ |
| public final void collect(T value, int doc) throws IOException { |
| GroupCollector<C> collector = groups.get(value); |
| collector.leafCollector.collect(doc); |
| } |
| |
| /** |
| * Set the Scorer on all group collectors |
| */ |
| public final void setScorer(Scorable scorer) throws IOException { |
| for (GroupCollector<C> collector : groups.values()) { |
| collector.leafCollector.setScorer(scorer); |
| } |
| } |
| |
| /** |
| * Called when the parent {@link SecondPassGroupingCollector} moves to a new segment |
| */ |
| public final void setNextReader(LeafReaderContext ctx) throws IOException { |
| for (GroupCollector<C> collector : groups.values()) { |
| collector.leafCollector = collector.collector.getLeafCollector(ctx); |
| } |
| } |
| |
| private static final class GroupCollector<C extends Collector> { |
| |
| final C collector; |
| LeafCollector leafCollector; |
| |
| private GroupCollector(C collector) { |
| this.collector = collector; |
| } |
| } |
| |
| } |