Lucene.Net  3.0.3
Lucene.Net is a port of the Lucene search engine library, written in C# and targeted at .NET runtime users.
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Scorer.cs
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17 
18 using System;
19 using Lucene.Net.Index;
20 
21 namespace Lucene.Net.Search
22 {
23 
24  /// <summary> Expert: Common scoring functionality for different types of queries.
25  ///
26  /// <p/>
27  /// A <c>Scorer</c> iterates over documents matching a
28  /// query in increasing order of doc Id.
29  /// <p/>
30  /// <p/>
31  /// Document scores are computed using a given <c>Similarity</c>
32  /// implementation.
33  /// <p/>
34  ///
35  /// <p/><b>NOTE</b>: The values Float.Nan,
36  /// Float.NEGATIVE_INFINITY and Float.POSITIVE_INFINITY are
37  /// not valid scores. Certain collectors (eg <see cref="TopScoreDocCollector" />
38  ///) will not properly collect hits
39  /// with these scores.
40  /// </summary>
41  public abstract class Scorer:DocIdSetIterator
42  {
43  private Similarity similarity;
44 
45  /// <summary>Constructs a Scorer.</summary>
46  /// <param name="similarity">The <c>Similarity</c> implementation used by this scorer.
47  /// </param>
48  protected internal Scorer(Similarity similarity)
49  {
50  this.similarity = similarity;
51  }
52 
53  /// <summary>Returns the Similarity implementation used by this scorer. </summary>
54  public virtual Similarity Similarity
55  {
56  get { return this.similarity; }
57  }
58 
59  /// <summary>Scores and collects all matching documents.</summary>
60  /// <param name="collector">The collector to which all matching documents are passed.
61  /// </param>
62  public virtual void Score(Collector collector)
63  {
64  collector.SetScorer(this);
65  int doc;
66  while ((doc = NextDoc()) != NO_MORE_DOCS)
67  {
68  collector.Collect(doc);
69  }
70  }
71 
72  /// <summary> Expert: Collects matching documents in a range. Hook for optimization.
73  /// Note, <paramref name="firstDocID" /> is added to ensure that <see cref="DocIdSetIterator.NextDoc()" />
74  /// was called before this method.
75  ///
76  /// </summary>
77  /// <param name="collector">The collector to which all matching documents are passed.
78  /// </param>
79  /// <param name="max">Do not score documents past this.
80  /// </param>
81  /// <param name="firstDocID">
82  /// The first document ID (ensures <see cref="DocIdSetIterator.NextDoc()" /> is called before
83  /// this method.
84  /// </param>
85  /// <returns> true if more matching documents may remain.
86  /// </returns>
87  public /*protected internal*/ virtual bool Score(Collector collector, int max, int firstDocID)
88  {
89  collector.SetScorer(this);
90  int doc = firstDocID;
91  while (doc < max)
92  {
93  collector.Collect(doc);
94  doc = NextDoc();
95  }
96  return doc != NO_MORE_DOCS;
97  }
98 
99  /// <summary>Returns the score of the current document matching the query.
100  /// Initially invalid, until <see cref="DocIdSetIterator.NextDoc()" /> or <see cref="DocIdSetIterator.Advance(int)" />
101  /// is called the first time, or when called from within
102  /// <see cref="Collector.Collect(int)" />.
103  /// </summary>
104  public abstract float Score();
105  }
106 }