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
  17 using System;
  18
  19 namespace Lucene.Net.Search
  20 {
  21
  22         /// <summary>Scorer for conjunctions, sets of queries, all of which are required. </summary>
  23         class ConjunctionScorer : Scorer
  24         {
  25                 private class AnonymousClassComparator : System.Collections.IComparer
  26                 {
  27                         public AnonymousClassComparator(ConjunctionScorer enclosingInstance)
  28                         {
  29                                 InitBlock(enclosingInstance);
  30                         }
  31                         private void  InitBlock(ConjunctionScorer enclosingInstance)
  32                         {
  33                                 this.enclosingInstance = enclosingInstance;
  34                         }
  35                         private ConjunctionScorer enclosingInstance;
  36                         public ConjunctionScorer Enclosing_Instance
  37                         {
  38                                 get
  39                                 {
  40                                         return enclosingInstance;
  41                                 }
  42
  43                         }
  44                         // sort the array
  45                         public virtual int Compare(System.Object o1, System.Object o2)
  46                         {
  47                                 return ((Scorer) o1).Doc() - ((Scorer) o2).Doc();
  48                         }
  49                 }
  50                 private System.Collections.ArrayList scorers = new System.Collections.ArrayList();
  51                 private bool firstTime = true;
  52                 private bool more = true;
  53                 private float coord;
  54
  55                 public ConjunctionScorer(Similarity similarity):base(similarity)
  56                 {
  57                 }
  58
  59                 internal void  Add(Scorer scorer)
  60                 {
  61                         scorers.Insert(scorers.Count, scorer);
  62                 }
  63
  64                 private Scorer First()
  65                 {
  66                         return (Scorer) scorers[0];
  67                 }
  68                 private Scorer Last()
  69                 {
  70                         return (Scorer) scorers[scorers.Count - 1];
  71                 }
  72
  73                 public override int Doc()
  74                 {
  75                         return First().Doc();
  76                 }
  77
  78                 public override bool Next()
  79                 {
  80                         if (firstTime)
  81                         {
  82                                 Init(true);
  83                         }
  84                         else if (more)
  85                         {
  86                                 more = Last().Next(); // trigger further scanning
  87                         }
  88                         return DoNext();
  89                 }
  90
  91                 private bool DoNext()
  92                 {
  93                         while (more && First().Doc() < Last().Doc())
  94                         {
  95                                 // find doc w/ all clauses
  96                                 more = First().SkipTo(Last().Doc()); // skip first upto last
  97                                 System.Object tempObject;
  98                                 tempObject = scorers[0];
  99                                 scorers.RemoveAt(0);
 100                                 scorers.Insert(scorers.Count, tempObject); // move first to last
 101                         }
 102                         return more; // found a doc with all clauses
 103                 }
 104
 105                 public override bool SkipTo(int target)
 106                 {
 107                         if (firstTime)
 108                         {
 109                                 Init(false);
 110                         }
 111
 112                         System.Collections.IEnumerator i = scorers.GetEnumerator();
 113                         while (more && i.MoveNext())
 114                         {
 115                                 more = ((Scorer) i.Current).SkipTo(target);
 116                         }
 117
 118                         if (more)
 119                                 SortScorers(); // re-sort scorers
 120
 121                         return DoNext();
 122                 }
 123
 124                 public override float Score()
 125                 {
 126                         float score = 0.0f; // sum scores
 127                         System.Collections.IEnumerator i = scorers.GetEnumerator();
 128                         while (i.MoveNext())
 129                         {
 130                                 score += ((Scorer) i.Current).Score();
 131                         }
 132                         score *= coord;
 133                         return score;
 134                 }
 135
 136                 private void  Init(bool initScorers)
 137                 {
 138                         //  compute coord factor
 139                         coord = GetSimilarity().Coord(scorers.Count, scorers.Count);
 140
 141                         more = scorers.Count > 0;
 142
 143                         if (initScorers)
 144                         {
 145                                 // move each scorer to its first entry
 146                                 System.Collections.IEnumerator i = scorers.GetEnumerator();
 147                                 while (more && i.MoveNext())
 148                                 {
 149                                         more = ((Scorer) i.Current).Next();
 150                                 }
 151                                 if (more)
 152                                         SortScorers(); // initial sort of list
 153                         }
 154
 155                         firstTime = false;
 156                 }
 157
 158                 private void  SortScorers()
 159                 {
 160                         // move scorers to an array
 161                         Scorer[] array = (Scorer[]) scorers.ToArray(typeof(Scorer));
 162                         scorers.Clear(); // empty the list
 163
 164                         // note that this comparator is not consistent with equals!
 165                         System.Array.Sort(array, new AnonymousClassComparator(this));
 166
 167                         for (int i = 0; i < array.Length; i++)
 168                         {
 169                                 scorers.Insert(scorers.Count, array[i]); // re-build list, now sorted
 170                         }
 171                 }
 172
 173                 public override Explanation Explain(int doc)
 174                 {
 175                         throw new System.NotSupportedException();
 176                 }
 177         }
 178 }