beagled/Lucene.Net/Search/Spans/SpanWeight.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 using IndexReader = Lucene.Net.Index.IndexReader;
  18 using Term = Lucene.Net.Index.Term;
  19 using Explanation = Lucene.Net.Search.Explanation;
  20 using Query = Lucene.Net.Search.Query;
  21 using Scorer = Lucene.Net.Search.Scorer;
  22 using Searcher = Lucene.Net.Search.Searcher;
  23 using Similarity = Lucene.Net.Search.Similarity;
  24 using Weight = Lucene.Net.Search.Weight;
  25 namespace Lucene.Net.Search.Spans
  26 {
  27
  28         [Serializable]
  29         class SpanWeight : Weight
  30         {
  31         virtual public Query Query
  32         {
  33             get
  34             {
  35                 return query;
  36             }
  37
  38         }
  39         virtual public float Value
  40         {
  41             get
  42             {
  43                 return value_Renamed;
  44             }
  45
  46         }
  47         private Searcher searcher;
  48                 private float value_Renamed;
  49                 private float idf;
  50                 private float queryNorm;
  51                 private float queryWeight;
  52
  53                 private System.Collections.ICollection terms;
  54                 private SpanQuery query;
  55
  56                 public SpanWeight(SpanQuery query, Searcher searcher)
  57                 {
  58                         this.searcher = searcher;
  59                         this.query = query;
  60                         this.terms = query.GetTerms();
  61                 }
  62
  63                 public virtual float SumOfSquaredWeights()
  64                 {
  65                         idf = this.query.GetSimilarity(searcher).Idf(terms, searcher);
  66                         queryWeight = idf * query.GetBoost(); // compute query weight
  67                         return queryWeight * queryWeight; // square it
  68                 }
  69
  70                 public virtual void  Normalize(float queryNorm)
  71                 {
  72                         this.queryNorm = queryNorm;
  73                         queryWeight *= queryNorm; // normalize query weight
  74                         value_Renamed = queryWeight * idf; // idf for document
  75                 }
  76
  77                 public virtual Scorer Scorer(IndexReader reader)
  78                 {
  79                         return new SpanScorer(query.GetSpans(reader), this, query.GetSimilarity(searcher), reader.Norms(query.GetField()));
  80                 }
  81
  82                 public virtual Explanation Explain(IndexReader reader, int doc)
  83                 {
  84
  85                         Explanation result = new Explanation();
  86                         result.SetDescription("weight(" + Query + " in " + doc + "), product of:");
  87                         System.String field = ((SpanQuery) Query).GetField();
  88
  89                         System.Text.StringBuilder docFreqs = new System.Text.StringBuilder();
  90                         System.Collections.IEnumerator i = terms.GetEnumerator();
  91                         while (i.MoveNext())
  92                         {
  93                                 Term term = (Term) i.Current;
  94                                 docFreqs.Append(term.Text());
  95                                 docFreqs.Append("=");
  96                                 docFreqs.Append(searcher.DocFreq(term));
  97
  98                                 if (i.MoveNext())
  99                                 {
 100                                         docFreqs.Append(" ");
 101                                 }
 102                         }
 103
 104                         Explanation idfExpl = new Explanation(idf, "idf(" + field + ": " + docFreqs + ")");
 105
 106                         // explain query weight
 107                         Explanation queryExpl = new Explanation();
 108                         queryExpl.SetDescription("queryWeight(" + Query + "), product of:");
 109
 110                         Explanation boostExpl = new Explanation(Query.GetBoost(), "boost");
 111                         if (Query.GetBoost() != 1.0f)
 112                                 queryExpl.AddDetail(boostExpl);
 113                         queryExpl.AddDetail(idfExpl);
 114
 115                         Explanation queryNormExpl = new Explanation(queryNorm, "queryNorm");
 116                         queryExpl.AddDetail(queryNormExpl);
 117
 118                         queryExpl.SetValue(boostExpl.GetValue() * idfExpl.GetValue() * queryNormExpl.GetValue());
 119
 120                         result.AddDetail(queryExpl);
 121
 122                         // explain Field weight
 123                         Explanation fieldExpl = new Explanation();
 124                         fieldExpl.SetDescription("fieldWeight(" + field + ":" + query.ToString(field) + " in " + doc + "), product of:");
 125
 126                         Explanation tfExpl = Scorer(reader).Explain(doc);
 127                         fieldExpl.AddDetail(tfExpl);
 128                         fieldExpl.AddDetail(idfExpl);
 129
 130                         Explanation fieldNormExpl = new Explanation();
 131                         byte[] fieldNorms = reader.Norms(field);
 132                         float fieldNorm = fieldNorms != null ? Similarity.DecodeNorm(fieldNorms[doc]) : 0.0f;
 133                         fieldNormExpl.SetValue(fieldNorm);
 134                         fieldNormExpl.SetDescription("fieldNorm(Field=" + field + ", doc=" + doc + ")");
 135                         fieldExpl.AddDetail(fieldNormExpl);
 136
 137                         fieldExpl.SetValue(tfExpl.GetValue() * idfExpl.GetValue() * fieldNormExpl.GetValue());
 138
 139                         result.AddDetail(fieldExpl);
 140
 141                         // combine them
 142                         result.SetValue(queryExpl.GetValue() * fieldExpl.GetValue());
 143
 144                         if (queryExpl.GetValue() == 1.0f)
 145                                 return fieldExpl;
 146
 147                         return result;
 148                 }
 149         }
 150 }