| 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 org.apache.lucene.index.AtomicReader; // javadocs |
| import org.apache.lucene.index.AtomicReaderContext; |
| import org.apache.lucene.util.Bits; |
| |
| /** |
| * Abstract base class for restricting which documents may |
| * be returned during searching. |
| */ |
| public abstract class Filter { |
| |
| /** |
| * Creates a {@link DocIdSet} enumerating the documents that should be |
| * permitted in search results. <b>NOTE:</b> null can be |
| * returned if no documents are accepted by this Filter. |
| * <p> |
| * Note: This method will be called once per segment in |
| * the index during searching. The returned {@link DocIdSet} |
| * must refer to document IDs for that segment, not for |
| * the top-level reader. |
| * |
| * @param context a {@link AtomicReaderContext} instance opened on the index currently |
| * searched on. Note, it is likely that the provided reader info does not |
| * represent the whole underlying index i.e. if the index has more than |
| * one segment the given reader only represents a single segment. |
| * The provided context is always an atomic context, so you can call |
| * {@link AtomicReader#fields()} |
| * on the context's reader, for example. |
| * |
| * @param acceptDocs |
| * Bits that represent the allowable docs to match (typically deleted docs |
| * but possibly filtering other documents) |
| * |
| * @return a DocIdSet that provides the documents which should be permitted or |
| * prohibited in search results. <b>NOTE:</b> <code>null</code> should be returned if |
| * the filter doesn't accept any documents otherwise internal optimization might not apply |
| * in the case an <i>empty</i> {@link DocIdSet} is returned. |
| */ |
| public abstract DocIdSet getDocIdSet(AtomicReaderContext context, Bits acceptDocs) throws IOException; |
| } |