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