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