beagled/Lucene.Net/Search/ReqOptSumScorer.cs

   1 /*
   2  * Copyright 2005 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>A Scorer for queries with a required part and an optional part.
  23         /// Delays skipTo() on the optional part until a score() is needed.
  24         /// <br>
  25         /// This <code>Scorer</code> implements {@link Scorer#SkipTo(int)}.
  26         /// </summary>
  27         public class ReqOptSumScorer : Scorer
  28         {
  29                 /// <summary>The scorers passed from the constructor.
  30                 /// These are set to null as soon as their next() or skipTo() returns false.
  31                 /// </summary>
  32                 private Scorer reqScorer;
  33                 private Scorer optScorer;
  34
  35                 /// <summary>Construct a <code>ReqOptScorer</code>.</summary>
  36                 /// <param name="reqScorer">The required scorer. This must match.
  37                 /// </param>
  38                 /// <param name="optScorer">The optional scorer. This is used for scoring only.
  39                 /// </param>
  40                 public ReqOptSumScorer(Scorer reqScorer, Scorer optScorer) : base(null)
  41                 { // No similarity used.
  42                         this.reqScorer = reqScorer;
  43                         this.optScorer = optScorer;
  44                 }
  45
  46                 private bool firstTimeOptScorer = true;
  47
  48                 public override bool Next()
  49                 {
  50                         return reqScorer.Next();
  51                 }
  52
  53                 public override bool SkipTo(int target)
  54                 {
  55                         return reqScorer.SkipTo(target);
  56                 }
  57
  58                 public override int Doc()
  59                 {
  60                         return reqScorer.Doc();
  61                 }
  62
  63                 /// <summary>Returns the score of the current document matching the query.
  64                 /// Initially invalid, until {@link #Next()} is called the first time.
  65                 /// </summary>
  66                 /// <returns> The score of the required scorer, eventually increased by the score
  67                 /// of the optional scorer when it also matches the current document.
  68                 /// </returns>
  69                 public override float Score()
  70                 {
  71                         int curDoc = reqScorer.Doc();
  72                         float reqScore = reqScorer.Score();
  73                         if (firstTimeOptScorer)
  74                         {
  75                                 firstTimeOptScorer = false;
  76                                 if (!optScorer.SkipTo(curDoc))
  77                                 {
  78                                         optScorer = null;
  79                                         return reqScore;
  80                                 }
  81                         }
  82                         else if (optScorer == null)
  83                         {
  84                                 return reqScore;
  85                         }
  86                         else if ((optScorer.Doc() < curDoc) && (!optScorer.SkipTo(curDoc)))
  87                         {
  88                                 optScorer = null;
  89                                 return reqScore;
  90                         }
  91                         // assert (optScorer != null) && (optScorer.doc() >= curDoc);
  92                         return (optScorer.Doc() == curDoc)?reqScore + optScorer.Score():reqScore;
  93                 }
  94
  95                 /// <summary>Explain the score of a document.</summary>
  96                 /// <todo>  Also show the total score. </todo>
  97                 /// <summary> See BooleanScorer.explain() on how to do this.
  98                 /// </summary>
  99                 public override Explanation Explain(int doc)
 100                 {
 101                         Explanation res = new Explanation();
 102                         res.SetDescription("required, optional");
 103                         res.AddDetail(reqScorer.Explain(doc));
 104                         res.AddDetail(optScorer.Explain(doc));
 105                         return res;
 106                 }
 107         }
 108 }