| package org.apache.lucene.search.grouping.term; |
| |
| /* |
| * 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 org.apache.lucene.index.AtomicReaderContext; |
| import org.apache.lucene.index.DocValues; |
| import org.apache.lucene.index.SortedDocValues; |
| import org.apache.lucene.search.LeafCollector; |
| import org.apache.lucene.search.Sort; |
| import org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector; |
| import org.apache.lucene.util.BytesRef; |
| |
| /** |
| * Concrete implementation of {@link org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector} that groups based on |
| * field values and more specifically uses {@link org.apache.lucene.index.SortedDocValues} |
| * to collect groups. |
| * |
| * @lucene.experimental |
| */ |
| public class TermFirstPassGroupingCollector extends AbstractFirstPassGroupingCollector<BytesRef> { |
| |
| private final BytesRef scratchBytesRef = new BytesRef(); |
| private SortedDocValues index; |
| |
| private String groupField; |
| |
| /** |
| * Create the first pass collector. |
| * |
| * @param groupField The field used to group |
| * documents. This field must be single-valued and |
| * indexed (DocValues is used to access its value |
| * per-document). |
| * @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 TermFirstPassGroupingCollector(String groupField, Sort groupSort, int topNGroups) throws IOException { |
| super(groupSort, topNGroups); |
| this.groupField = groupField; |
| } |
| |
| @Override |
| protected BytesRef getDocGroupValue(int doc) { |
| final int ord = index.getOrd(doc); |
| if (ord == -1) { |
| return null; |
| } else { |
| index.lookupOrd(ord, scratchBytesRef); |
| return scratchBytesRef; |
| } |
| } |
| |
| @Override |
| protected BytesRef copyDocGroupValue(BytesRef groupValue, BytesRef reuse) { |
| if (groupValue == null) { |
| return null; |
| } else if (reuse != null) { |
| reuse.copyBytes(groupValue); |
| return reuse; |
| } else { |
| return BytesRef.deepCopyOf(groupValue); |
| } |
| } |
| |
| @Override |
| protected void doSetNextReader(AtomicReaderContext readerContext) throws IOException { |
| super.doSetNextReader(readerContext); |
| index = DocValues.getSorted(readerContext.reader(), groupField); |
| } |
| } |