beagled/Lucene.Net/Analysis/PerFieldAnalyzerWrapper.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
  19 namespace Lucene.Net.Analysis
  20 {
  21
  22         /// <summary> This analyzer is used to facilitate scenarios where different
  23         /// fields require different analysis techniques.  Use {@link #addAnalyzer}
  24         /// to add a non-default analyzer on a field name basis.
  25         ///
  26         /// <p>Example usage:
  27         ///
  28         /// <pre>
  29         /// PerFieldAnalyzerWrapper aWrapper =
  30         /// new PerFieldAnalyzerWrapper(new StandardAnalyzer());
  31         /// aWrapper.addAnalyzer("firstname", new KeywordAnalyzer());
  32         /// aWrapper.addAnalyzer("lastname", new KeywordAnalyzer());
  33         /// </pre>
  34         ///
  35         /// <p>In this example, StandardAnalyzer will be used for all fields except "firstname"
  36         /// and "lastname", for which KeywordAnalyzer will be used.
  37         ///
  38         /// <p>A PerFieldAnalyzerWrapper can be used like any other analyzer, for both indexing
  39         /// and query parsing.
  40         /// </summary>
  41         public class PerFieldAnalyzerWrapper:Analyzer
  42         {
  43                 private Analyzer defaultAnalyzer;
  44                 private System.Collections.IDictionary analyzerMap = new System.Collections.Hashtable();
  45
  46
  47                 /// <summary> Constructs with default analyzer.
  48                 ///
  49                 /// </summary>
  50                 /// <param name="defaultAnalyzer">Any fields not specifically
  51                 /// defined to use a different analyzer will use the one provided here.
  52                 /// </param>
  53                 public PerFieldAnalyzerWrapper(Analyzer defaultAnalyzer)
  54                 {
  55                         this.defaultAnalyzer = defaultAnalyzer;
  56                 }
  57
  58                 /// <summary> Defines an analyzer to use for the specified field.
  59                 ///
  60                 /// </summary>
  61                 /// <param name="fieldName">field name requiring a non-default analyzer
  62                 /// </param>
  63                 /// <param name="analyzer">non-default analyzer to use for field
  64                 /// </param>
  65                 public virtual void  AddAnalyzer(System.String fieldName, Analyzer analyzer)
  66                 {
  67                         analyzerMap[fieldName] = analyzer;
  68                 }
  69
  70                 public override TokenStream TokenStream(System.String fieldName, System.IO.TextReader reader)
  71                 {
  72                         Analyzer analyzer = (Analyzer) analyzerMap[fieldName];
  73                         if (analyzer == null)
  74                         {
  75                                 analyzer = defaultAnalyzer;
  76                         }
  77
  78                         return analyzer.TokenStream(fieldName, reader);
  79                 }
  80
  81                 public override System.String ToString()
  82                 {
  83                         // {{Aroush-1.9}} 'analyzerMap.ToString()' may return a different value then Java.
  84                         return "PerFieldAnalyzerWrapper(" + analyzerMap.ToString() + ", default=" + defaultAnalyzer + ")";
  85                 }
  86         }
  87 }