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 using System;
  17 namespace Lucene.Net.Search
  18 {
  19
  20     /// <summary>A Scorer for queries with a required part and an optional part.
  21     /// Delays SkipTo() on the optional part until a score() is needed.
  22     /// <br>
  23     /// This <code>Scorer</code> implements {@link Scorer#SkipTo(int)}.
  24     /// </summary>
  25     public class ReqOptSumScorer : Scorer
  26     {
  27         /// <summary>The scorers passed from the constructor.
  28         /// These are set to null as soon as their Next() or SkipTo() returns false.
  29         /// </summary>
  30         private Scorer reqScorer;
  31         private Scorer optScorer;
  32
  33         /// <summary>Construct a <code>ReqOptScorer</code>.</summary>
  34         /// <param name="reqScorer">The required scorer. This must match.
  35         /// </param>
  36         /// <param name="optScorer">The optional scorer. This is used for scoring only.
  37         /// </param>
  38         public ReqOptSumScorer(Scorer reqScorer, Scorer optScorer) : base(null)
  39         { // No similarity used.
  40             this.reqScorer = reqScorer;
  41             this.optScorer = optScorer;
  42         }
  43
  44         private bool firstTimeOptScorer = true;
  45
  46         public override bool Next()
  47         {
  48             return reqScorer.Next();
  49         }
  50
  51         public override bool SkipTo(int target)
  52         {
  53             return reqScorer.SkipTo(target);
  54         }
  55
  56         public override int Doc()
  57         {
  58             return reqScorer.Doc();
  59         }
  60
  61         /// <summary>Returns the score of the current document matching the query.
  62         /// Initially invalid, until {@link #Next()} is called the first time.
  63         /// </summary>
  64         /// <returns> The score of the required scorer, eventually increased by the score
  65         /// of the optional scorer when it also matches the current document.
  66         /// </returns>
  67         public override float Score()
  68         {
  69             int curDoc = reqScorer.Doc();
  70             float reqScore = reqScorer.Score();
  71             if (firstTimeOptScorer)
  72             {
  73                 firstTimeOptScorer = false;
  74                 if (!optScorer.SkipTo(curDoc))
  75                 {
  76                     optScorer = null;
  77                     return reqScore;
  78                 }
  79             }
  80             else if (optScorer == null)
  81             {
  82                 return reqScore;
  83             }
  84             else if ((optScorer.Doc() < curDoc) && (!optScorer.SkipTo(curDoc)))
  85             {
  86                 optScorer = null;
  87                 return reqScore;
  88             }
  89             // assert (optScorer != null) && (optScorer.doc() >= curDoc);
  90             return (optScorer.Doc() == curDoc)?reqScore + optScorer.Score():reqScore;
  91         }
  92
  93         /// <summary>Explain the score of a document.</summary>
  94         /// <todo>  Also show the total score. </todo>
  95         /// <summary> See BooleanScorer.explain() on how to do this.
  96         /// </summary>
  97         public override Explanation Explain(int doc)
  98         {
  99             Explanation res = new Explanation();
 100             res.SetDescription("required, optional");
 101             res.AddDetail(reqScorer.Explain(doc));
 102             res.AddDetail(optScorer.Explain(doc));
 103             return res;
 104         }
 105     }
 106 }