Lucene.Net  3.0.3
Lucene.Net is a port of the Lucene search engine library, written in C# and targeted at .NET runtime users.
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Properties Pages
Filter.cs
Go to the documentation of this file.
1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 using System;
19 
20 using IndexReader = Lucene.Net.Index.IndexReader;
21 using DocIdBitSet = Lucene.Net.Util.DocIdBitSet;
22 
23 namespace Lucene.Net.Search
24 {
25 
26  /// <summary>Abstract base class for restricting which documents may be returned during searching.</summary>
27  [Serializable]
28  public abstract class Filter
29  {
30  ///<summary>
31  /// <para>Creates a <see cref="DocIdSet" /> enumerating the documents that should be
32  /// permitted in search results. <b>NOTE:</b> null can be
33  /// returned if no documents are accepted by this Filter.</para>
34  /// <p/>
35  /// <para>Note: This method will be called once per segment in
36  /// the index during searching. The returned <see cref="DocIdSet" />
37  /// must refer to document IDs for that segment, not for
38  /// the top-level reader.</para>
39  ///</summary>
40  /// <returns> a DocIdSet that provides the documents which should be permitted or
41  /// prohibited in search results. <b>NOTE:</b> null can be returned if
42  /// no documents will be accepted by this Filter.
43  /// </returns>
44  /// <param name="reader">
45  /// A <see cref="IndexReader" /> instance opened on the index currently
46  /// searched on. Note, it is likely that the provided reader does not
47  /// represent the whole underlying index i.e. if the index has more than
48  /// one segment the given reader only represents a single segment.
49  /// </param>
50  /// <seealso cref="DocIdBitSet">
51  /// </seealso>
52  public abstract DocIdSet GetDocIdSet(IndexReader reader);
53  }
54 }