| package org.apache.lucene.search; |
| |
| /* |
| * 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.ArrayList; |
| import java.util.Arrays; |
| import java.util.List; |
| |
| import org.apache.lucene.index.LeafReaderContext; |
| |
| /** |
| * A {@link Collector} which allows running a search with several |
| * {@link Collector}s. It offers a static {@link #wrap} method which accepts a |
| * list of collectors and wraps them with {@link MultiCollector}, while |
| * filtering out the <code>null</code> null ones. |
| */ |
| public class MultiCollector implements Collector { |
| |
| /** See {@link #wrap(Iterable)}. */ |
| public static Collector wrap(Collector... collectors) { |
| return wrap(Arrays.asList(collectors)); |
| } |
| |
| /** |
| * Wraps a list of {@link Collector}s with a {@link MultiCollector}. This |
| * method works as follows: |
| * <ul> |
| * <li>Filters out the <code>null</code> collectors, so they are not used |
| * during search time. |
| * <li>If the input contains 1 real collector (i.e. non-<code>null</code> ), |
| * it is returned. |
| * <li>Otherwise the method returns a {@link MultiCollector} which wraps the |
| * non-<code>null</code> ones. |
| * </ul> |
| * |
| * @throws IllegalArgumentException |
| * if either 0 collectors were input, or all collectors are |
| * <code>null</code>. |
| */ |
| public static Collector wrap(Iterable<? extends Collector> collectors) { |
| // For the user's convenience, we allow null collectors to be passed. |
| // However, to improve performance, these null collectors are found |
| // and dropped from the array we save for actual collection time. |
| int n = 0; |
| for (Collector c : collectors) { |
| if (c != null) { |
| n++; |
| } |
| } |
| |
| if (n == 0) { |
| throw new IllegalArgumentException("At least 1 collector must not be null"); |
| } else if (n == 1) { |
| // only 1 Collector - return it. |
| Collector col = null; |
| for (Collector c : collectors) { |
| if (c != null) { |
| col = c; |
| break; |
| } |
| } |
| return col; |
| } else { |
| Collector[] colls = new Collector[n]; |
| n = 0; |
| for (Collector c : collectors) { |
| if (c != null) { |
| colls[n++] = c; |
| } |
| } |
| return new MultiCollector(colls); |
| } |
| } |
| |
| private final boolean cacheScores; |
| private final Collector[] collectors; |
| |
| private MultiCollector(Collector... collectors) { |
| this.collectors = collectors; |
| int numNeedsScores = 0; |
| for (Collector collector : collectors) { |
| if (collector.needsScores()) { |
| numNeedsScores += 1; |
| } |
| } |
| this.cacheScores = numNeedsScores >= 2; |
| } |
| |
| @Override |
| public boolean needsScores() { |
| for (Collector collector : collectors) { |
| if (collector.needsScores()) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| @Override |
| public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException { |
| final List<LeafCollector> leafCollectors = new ArrayList<>(); |
| for (Collector collector : collectors) { |
| final LeafCollector leafCollector; |
| try { |
| leafCollector = collector.getLeafCollector(context); |
| } catch (CollectionTerminatedException e) { |
| // this leaf collector does not need this segment |
| continue; |
| } |
| leafCollectors.add(leafCollector); |
| } |
| switch (leafCollectors.size()) { |
| case 0: |
| throw new CollectionTerminatedException(); |
| case 1: |
| return leafCollectors.get(0); |
| default: |
| return new MultiLeafCollector(leafCollectors, cacheScores); |
| } |
| } |
| |
| private static class MultiLeafCollector implements LeafCollector { |
| |
| private final boolean cacheScores; |
| private final LeafCollector[] collectors; |
| private int numCollectors; |
| |
| private MultiLeafCollector(List<LeafCollector> collectors, boolean cacheScores) { |
| this.collectors = collectors.toArray(new LeafCollector[collectors.size()]); |
| this.cacheScores = cacheScores; |
| this.numCollectors = this.collectors.length; |
| } |
| |
| @Override |
| public void setScorer(Scorer scorer) throws IOException { |
| if (cacheScores) { |
| scorer = new ScoreCachingWrappingScorer(scorer); |
| } |
| for (int i = 0; i < numCollectors; ++i) { |
| final LeafCollector c = collectors[i]; |
| c.setScorer(scorer); |
| } |
| } |
| |
| private void removeCollector(int i) { |
| System.arraycopy(collectors, i + 1, collectors, i, numCollectors - i - 1); |
| --numCollectors; |
| collectors[numCollectors] = null; |
| } |
| |
| @Override |
| public void collect(int doc) throws IOException { |
| final LeafCollector[] collectors = this.collectors; |
| int numCollectors = this.numCollectors; |
| for (int i = 0; i < numCollectors; ) { |
| final LeafCollector collector = collectors[i]; |
| try { |
| collector.collect(doc); |
| ++i; |
| } catch (CollectionTerminatedException e) { |
| removeCollector(i); |
| numCollectors = this.numCollectors; |
| if (numCollectors == 0) { |
| throw new CollectionTerminatedException(); |
| } |
| } |
| } |
| } |
| |
| } |
| |
| } |