/*
* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using Token = Lucene.Net.Analysis.Token;
using TokenFilter = Lucene.Net.Analysis.TokenFilter;
using TokenStream = Lucene.Net.Analysis.TokenStream;
namespace Lucene.Net.Analysis.RU
{
/// A filter that stems Russian words. The implementation was inspired by GermanStemFilter.
/// The input should be filtered by RussianLowerCaseFilter before passing it to RussianStemFilter ,
/// because RussianStemFilter only works with lowercase part of any "russian" charset.
///
///
/// Boris Okner, b.okner@rogers.com
///
/// $Id: RussianStemFilter.java,v 1.5 2004/03/29 22:48:01 cutting Exp $
///
public sealed class RussianStemFilter : TokenFilter
{
/// The actual token in the input stream.
private Token token = null;
private RussianStemmer stemmer = null;
public RussianStemFilter(TokenStream in_Renamed, char[] charset):base(in_Renamed)
{
stemmer = new RussianStemmer(charset);
}
/// Returns the next token in the stream, or null at EOS
///
public override Token Next()
{
if ((token = input.Next()) == null)
{
return null;
}
else
{
System.String s = stemmer.Stem(token.TermText());
if (!s.Equals(token.TermText()))
{
return new Token(s, token.StartOffset(), token.EndOffset(), token.Type());
}
return token;
}
}
/// Set a alternative/custom RussianStemmer for this filter.
public void SetStemmer(RussianStemmer stemmer)
{
if (stemmer != null)
{
this.stemmer = stemmer;
}
}
}
}