beagled/Lucene.Net/Search/QueryFilter.cs

   1 /*
   2  * Copyright 2004 The Apache Software Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 using System;
  18 using System.Runtime.InteropServices;
  19 using IndexReader = Lucene.Net.Index.IndexReader;
  20
  21 namespace Lucene.Net.Search
  22 {
  23
  24         /// <summary>Constrains search results to only match those which also match a provided
  25         /// query.  Results are cached, so that searches after the first on the same
  26         /// index using this filter are much faster.
  27         ///
  28         /// <p> This could be used, for example, with a {@link RangeQuery} on a suitably
  29         /// formatted date field to implement date filtering.  One could re-use a single
  30         /// QueryFilter that matches, e.g., only documents modified within the last
  31         /// week.  The QueryFilter and RangeQuery would only need to be reconstructed
  32         /// once per day.
  33         ///
  34         /// </summary>
  35         /// <version>  $Id: QueryFilter.cs,v 1.4 2006/10/02 17:09:06 joeshaw Exp $
  36         /// </version>
  37         [Serializable]
  38         public class QueryFilter : Filter
  39         {
  40                 private class AnonymousClassHitCollector : HitCollector
  41                 {
  42                         public AnonymousClassHitCollector(System.Collections.BitArray bits, QueryFilter enclosingInstance)
  43                         {
  44                                 InitBlock(bits, enclosingInstance);
  45                         }
  46                         private void  InitBlock(System.Collections.BitArray bits, QueryFilter enclosingInstance)
  47                         {
  48                                 this.bits = bits;
  49                                 this.enclosingInstance = enclosingInstance;
  50                         }
  51                         private System.Collections.BitArray bits;
  52                         private QueryFilter enclosingInstance;
  53                         public QueryFilter Enclosing_Instance
  54                         {
  55                                 get
  56                                 {
  57                                         return enclosingInstance;
  58                                 }
  59
  60                         }
  61                         public override void  Collect(int doc, float score)
  62                         {
  63                                 bits.Set(doc, true); // set bit for hit
  64                         }
  65                 }
  66                 private Query query;
  67                 [NonSerialized]
  68                 private System.Collections.Hashtable cache = null;
  69
  70                 /// <summary>Constructs a filter which only matches documents matching
  71                 /// <code>query</code>.
  72                 /// </summary>
  73                 public QueryFilter(Query query)
  74                 {
  75                         this.query = query;
  76                 }
  77
  78                 public override System.Collections.BitArray Bits(IndexReader reader)
  79                 {
  80
  81                         if (cache == null)
  82                         {
  83                                 cache = new System.Collections.Hashtable();
  84                         }
  85
  86                         lock (cache.SyncRoot)
  87                         {
  88                                 // check cache
  89                                 System.Collections.BitArray cached = (System.Collections.BitArray) cache[reader];
  90                                 if (cached != null)
  91                                 {
  92                                         return cached;
  93                                 }
  94                         }
  95
  96                         System.Collections.BitArray bits = new System.Collections.BitArray((reader.MaxDoc() % 64 == 0?reader.MaxDoc() / 64:reader.MaxDoc() / 64 + 1) * 64);
  97
  98                         new IndexSearcher(reader).Search(query, new AnonymousClassHitCollector(bits, this));
  99
 100                         lock (cache.SyncRoot)
 101                         {
 102                                 // update cache
 103                                 cache[reader] = bits;
 104                         }
 105
 106                         return bits;
 107                 }
 108
 109                 public override System.String ToString()
 110                 {
 111                         return "QueryFilter(" + query + ")";
 112                 }
 113
 114                 public  override bool Equals(System.Object o)
 115                 {
 116                         if (!(o is QueryFilter))
 117                                 return false;
 118                         return this.query.Equals(((QueryFilter) o).query);
 119                 }
 120
 121                 public override int GetHashCode()
 122                 {
 123                         return query.GetHashCode() ^ (unchecked((int) 0x923F64B9L));     // {{Aroush-1.9}} Is this OK?!
 124                 }
 125         }
 126 }