| /* |
| * 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.index; |
| |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.concurrent.ConcurrentHashMap; |
| |
| import org.apache.lucene.util.MergedIterator; |
| |
| /** |
| * Provides a single {@link Fields} term index view over an |
| * {@link IndexReader}. |
| * This is useful when you're interacting with an {@link |
| * IndexReader} implementation that consists of sequential |
| * sub-readers (eg {@link DirectoryReader} or {@link |
| * MultiReader}) and you must treat it as a {@link LeafReader}. |
| * |
| * <p><b>NOTE</b>: for composite readers, you'll get better |
| * performance by gathering the sub readers using |
| * {@link IndexReader#getContext()} to get the |
| * atomic leaves and then operate per-LeafReader, |
| * instead of using this class. |
| * |
| * @lucene.internal |
| */ |
| public final class MultiFields extends Fields { |
| private final Fields[] subs; |
| private final ReaderSlice[] subSlices; |
| private final Map<String,Terms> terms = new ConcurrentHashMap<>(); |
| |
| /** |
| * Sole constructor. |
| */ |
| public MultiFields(Fields[] subs, ReaderSlice[] subSlices) { |
| this.subs = subs; |
| this.subSlices = subSlices; |
| } |
| |
| @SuppressWarnings({"unchecked","rawtypes"}) |
| @Override |
| public Iterator<String> iterator() { |
| Iterator<String> subIterators[] = new Iterator[subs.length]; |
| for(int i=0;i<subs.length;i++) { |
| subIterators[i] = subs[i].iterator(); |
| } |
| return new MergedIterator<>(subIterators); |
| } |
| |
| @Override |
| public Terms terms(String field) throws IOException { |
| Terms result = terms.get(field); |
| if (result != null) |
| return result; |
| |
| |
| // Lazy init: first time this field is requested, we |
| // create & add to terms: |
| final List<Terms> subs2 = new ArrayList<>(); |
| final List<ReaderSlice> slices2 = new ArrayList<>(); |
| |
| // Gather all sub-readers that share this field |
| for(int i=0;i<subs.length;i++) { |
| final Terms terms = subs[i].terms(field); |
| if (terms != null) { |
| subs2.add(terms); |
| slices2.add(subSlices[i]); |
| } |
| } |
| if (subs2.size() == 0) { |
| result = null; |
| // don't cache this case with an unbounded cache, since the number of fields that don't exist |
| // is unbounded. |
| } else { |
| result = new MultiTerms(subs2.toArray(Terms.EMPTY_ARRAY), |
| slices2.toArray(ReaderSlice.EMPTY_ARRAY)); |
| terms.put(field, result); |
| } |
| |
| return result; |
| } |
| |
| @Override |
| public int size() { |
| return -1; |
| } |
| |
| } |
| |