| /* |
| * 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; |
| |
| |
| import java.io.IOException; |
| |
| import org.apache.lucene.index.LeafReaderContext; |
| |
| /** |
| * <p>Expert: Collectors are primarily meant to be used to |
| * gather raw results from a search, and implement sorting |
| * or custom result filtering, collation, etc. </p> |
| * |
| * <p>Lucene's core collectors are derived from {@link Collector} |
| * and {@link SimpleCollector}. Likely your application can |
| * use one of these classes, or subclass {@link TopDocsCollector}, |
| * instead of implementing Collector directly: |
| * |
| * <ul> |
| * |
| * <li>{@link TopDocsCollector} is an abstract base class |
| * that assumes you will retrieve the top N docs, |
| * according to some criteria, after collection is |
| * done. </li> |
| * |
| * <li>{@link TopScoreDocCollector} is a concrete subclass |
| * {@link TopDocsCollector} and sorts according to score + |
| * docID. This is used internally by the {@link |
| * IndexSearcher} search methods that do not take an |
| * explicit {@link Sort}. It is likely the most frequently |
| * used collector.</li> |
| * |
| * <li>{@link TopFieldCollector} subclasses {@link |
| * TopDocsCollector} and sorts according to a specified |
| * {@link Sort} object (sort by field). This is used |
| * internally by the {@link IndexSearcher} search methods |
| * that take an explicit {@link Sort}. |
| * |
| * <li>{@link TimeLimitingCollector}, which wraps any other |
| * Collector and aborts the search if it's taken too much |
| * time.</li> |
| * |
| * <li>{@link PositiveScoresOnlyCollector} wraps any other |
| * Collector and prevents collection of hits whose score |
| * is <= 0.0</li> |
| * |
| * </ul> |
| * |
| * @lucene.experimental |
| */ |
| public interface Collector { |
| |
| /** |
| * Create a new {@link LeafCollector collector} to collect the given context. |
| * |
| * @param context |
| * next atomic reader context |
| */ |
| LeafCollector getLeafCollector(LeafReaderContext context) throws IOException; |
| |
| /** |
| * Indicates what features are required from the scorer. |
| */ |
| ScoreMode scoreMode(); |
| } |