Lucene.Net  3.0.3
Lucene.Net is a .NET port of the Java Lucene Indexing Library
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BrazilianStemFilter.cs
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1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 using System.Collections.Generic;
19 using Lucene.Net.Analysis;
20 using System.Collections;
21 using Lucene.Net.Analysis.Tokenattributes;
22 using Version = Lucene.Net.Util.Version;
23 
24 
25 /*
26  * Based on GermanStemFilter
27  *
28  */
29 namespace Lucene.Net.Analysis.BR
30 {
31 
32  public sealed class BrazilianStemFilter : TokenFilter
33  {
34 
35  /*
36  * The actual token in the input stream.
37  */
38  private BrazilianStemmer stemmer = null;
39  private ISet<string> exclusions = null;
40  private ITermAttribute termAtt;
41 
43  : base(input)
44  {
45  stemmer = new BrazilianStemmer();
46  termAtt = AddAttribute<ITermAttribute>();
47  }
48 
49  public BrazilianStemFilter(TokenStream input, ISet<string> exclusiontable)
50  : this(input)
51  {
52  this.exclusions = exclusiontable;
53  }
54 
55  /*
56  * <returns>Returns the next token in the stream, or null at EOS.</returns>
57  */
58  public override bool IncrementToken()
59  {
60  if (input.IncrementToken())
61  {
62  string term = termAtt.Term;
63  // Check the exclusion table.
64  if (exclusions == null || !exclusions.Contains(term))
65  {
66  string s = stemmer.Stem(term);
67  // If not stemmed, don't waste the time adjusting the token.
68  if ((s != null) && !s.Equals(term))
69  termAtt.SetTermBuffer(s);
70  }
71  return true;
72  }
73  else
74  {
75  return false;
76  }
77  }
78  }
79 }