| /* |
| * 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 org.apache.lucene.index.LeafReaderContext; |
| import org.apache.lucene.search.Scorable; |
| |
| /** |
| * Defines a group, for use by grouping collectors |
| * |
| * <p>A GroupSelector acts as an iterator over documents. For each segment, clients should call |
| * {@link #setNextReader(LeafReaderContext)}, and then {@link #advanceTo(int)} for each matching |
| * document. |
| * |
| * @param <T> the type of the group value |
| */ |
| public abstract class GroupSelector<T> { |
| |
| /** What to do with the current value */ |
| public enum State { |
| SKIP, |
| ACCEPT |
| } |
| |
| /** Set the LeafReaderContext */ |
| public abstract void setNextReader(LeafReaderContext readerContext) throws IOException; |
| |
| /** Set the current Scorer */ |
| public abstract void setScorer(Scorable scorer) throws IOException; |
| |
| /** Advance the GroupSelector's iterator to the given document */ |
| public abstract State advanceTo(int doc) throws IOException; |
| |
| /** |
| * Get the group value of the current document |
| * |
| * <p>N.B. this object may be reused, for a persistent version use {@link #copyValue()} |
| */ |
| public abstract T currentValue() throws IOException; |
| |
| /** @return a copy of the group value of the current document */ |
| public abstract T copyValue() throws IOException; |
| |
| /** |
| * Set a restriction on the group values returned by this selector |
| * |
| * <p>If the selector is positioned on a document whose group value is not contained within this |
| * set, then {@link #advanceTo(int)} will return {@link State#SKIP} |
| * |
| * @param groups a set of {@link SearchGroup} objects to limit selections to |
| */ |
| public abstract void setGroups(Collection<SearchGroup<T>> groups); |
| } |