beagled/Lucene.Net/Analysis/RU/RussianLetterTokenizer.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 CharTokenizer = Lucene.Net.Analysis.CharTokenizer;
  18 namespace Lucene.Net.Analysis.RU
  19 {
  20
  21         /// <summary> A RussianLetterTokenizer is a tokenizer that extends LetterTokenizer by additionally looking up letters
  22         /// in a given "russian charset". The problem with LeterTokenizer is that it uses Character.isLetter() method,
  23         /// which doesn't know how to detect letters in encodings like CP1252 and KOI8
  24         /// (well-known problems with 0xD7 and 0xF7 chars)
  25         ///
  26         /// </summary>
  27         /// <author>   Boris Okner, b.okner@rogers.com
  28         /// </author>
  29         /// <version>  $Id: RussianLetterTokenizer.cs,v 1.2 2005/01/17 19:54:28 joeshaw Exp $
  30         /// </version>
  31
  32         public class RussianLetterTokenizer : CharTokenizer
  33         {
  34                 /// <summary>Construct a new LetterTokenizer. </summary>
  35                 private char[] charset;
  36
  37                 public RussianLetterTokenizer(System.IO.TextReader in_Renamed, char[] charset) : base(in_Renamed)
  38                 {
  39                         this.charset = charset;
  40                 }
  41
  42                 /// <summary> Collects only characters which satisfy
  43                 /// {@link Character#isLetter(char)}.
  44                 /// </summary>
  45                 protected internal override bool IsTokenChar(char c)
  46                 {
  47                         if (System.Char.IsLetter(c))
  48                                 return true;
  49                         for (int i = 0; i < charset.Length; i++)
  50                         {
  51                                 if (c == charset[i])
  52                                         return true;
  53                         }
  54                         return false;
  55                 }
  56         }
  57 }