beagled/Lucene.Net/Search/ConjunctionScorer.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 using System;
  17 namespace Lucene.Net.Search
  18 {
  19
  20         /// <summary>Scorer for conjunctions, sets of queries, all of which are required. </summary>
  21         class ConjunctionScorer : Scorer
  22         {
  23                 private class AnonymousClassComparator : System.Collections.IComparer
  24                 {
  25                         public AnonymousClassComparator(ConjunctionScorer enclosingInstance)
  26                         {
  27                                 InitBlock(enclosingInstance);
  28                         }
  29                         private void  InitBlock(ConjunctionScorer enclosingInstance)
  30                         {
  31                                 this.enclosingInstance = enclosingInstance;
  32                         }
  33                         private ConjunctionScorer enclosingInstance;
  34                         public ConjunctionScorer Enclosing_Instance
  35                         {
  36                                 get
  37                                 {
  38                                         return enclosingInstance;
  39                                 }
  40
  41                         }
  42                         // sort the array
  43                         public virtual int Compare(System.Object o1, System.Object o2)
  44                         {
  45                                 return ((Scorer) o1).Doc() - ((Scorer) o2).Doc();
  46                         }
  47                 }
  48                 private System.Collections.ArrayList scorers = new System.Collections.ArrayList();
  49                 private bool firstTime = true;
  50                 private bool more = true;
  51                 private float coord;
  52
  53                 public ConjunctionScorer(Similarity similarity):base(similarity)
  54                 {
  55                 }
  56
  57                 internal void  Add(Scorer scorer)
  58                 {
  59                         scorers.Insert(scorers.Count, scorer);
  60                 }
  61
  62                 private Scorer First()
  63                 {
  64                         return (Scorer) scorers[0];
  65                 }
  66                 private Scorer Last()
  67                 {
  68                         return (Scorer) scorers[scorers.Count - 1];
  69                 }
  70
  71                 public override int Doc()
  72                 {
  73                         return First().Doc();
  74                 }
  75
  76                 public override bool Next()
  77                 {
  78                         if (firstTime)
  79                         {
  80                                 Init(true);
  81                         }
  82                         else if (more)
  83                         {
  84                                 more = Last().Next(); // trigger further scanning
  85                         }
  86                         return DoNext();
  87                 }
  88
  89                 private bool DoNext()
  90                 {
  91                         while (more && First().Doc() < Last().Doc())
  92                         {
  93                                 // find doc w/ all clauses
  94                                 more = First().SkipTo(Last().Doc()); // skip first upto last
  95                                 System.Object tempObject;
  96                                 tempObject = scorers[0];
  97                                 scorers.RemoveAt(0);
  98                                 scorers.Insert(scorers.Count, tempObject); // move first to last
  99                         }
 100                         return more; // found a doc with all clauses
 101                 }
 102
 103                 public override bool SkipTo(int target)
 104                 {
 105             if (firstTime)
 106             {
 107                 Init(false);
 108             }
 109
 110             System.Collections.IEnumerator i = scorers.GetEnumerator();
 111                         while (more && i.MoveNext())
 112                         {
 113                                 more = ((Scorer) i.Current).SkipTo(target);
 114                         }
 115
 116             if (more)
 117                                 SortScorers(); // re-sort scorers
 118
 119             return DoNext();
 120                 }
 121
 122                 public override float Score()
 123                 {
 124                         float score = 0.0f; // sum scores
 125                         System.Collections.IEnumerator i = scorers.GetEnumerator();
 126                         while (i.MoveNext())
 127                         {
 128                                 score += ((Scorer) i.Current).Score();
 129                         }
 130                         score *= coord;
 131                         return score;
 132                 }
 133
 134                 private void  Init(bool initScorers)
 135                 {
 136             //  compute coord factor
 137             coord = GetSimilarity().Coord(scorers.Count, scorers.Count);
 138
 139             more = scorers.Count > 0;
 140
 141             if (initScorers)
 142             {
 143                 // move each scorer to its first entry
 144                 System.Collections.IEnumerator i = scorers.GetEnumerator();
 145                 while (more && i.MoveNext())
 146                 {
 147                     more = ((Scorer) i.Current).Next();
 148                 }
 149                 if (more)
 150                     SortScorers(); // initial sort of list
 151             }
 152
 153             firstTime = false;
 154         }
 155
 156                 private void  SortScorers()
 157                 {
 158                         // move scorers to an array
 159             Scorer[] array = (Scorer[]) scorers.ToArray(typeof(Scorer));
 160                         scorers.Clear(); // empty the list
 161
 162                         // note that this comparator is not consistent with equals!
 163                         System.Array.Sort(array, new AnonymousClassComparator(this));
 164
 165                         for (int i = 0; i < array.Length; i++)
 166                         {
 167                                 scorers.Insert(scorers.Count, array[i]); // re-build list, now sorted
 168                         }
 169                 }
 170
 171                 public override Explanation Explain(int doc)
 172                 {
 173                         throw new System.NotSupportedException();
 174                 }
 175         }
 176 }