1 files changed, 62 insertions, 0 deletions
diff --git a/src/core/Analysis/PorterStemFilter.cs b/src/core/Analysis/PorterStemFilter.cs
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+++ b/src/core/Analysis/PorterStemFilter.cs
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+/* 
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 Lucene.Net.Analysis.Tokenattributes;
+
+namespace Lucene.Net.Analysis
+{
+	
+	/// <summary>Transforms the token stream as per the Porter stemming algorithm.
+	/// Note: the input to the stemming filter must already be in lower case,
+	/// so you will need to use LowerCaseFilter or LowerCaseTokenizer farther
+	/// down the Tokenizer chain in order for this to work properly!
+	/// <p/>
+	/// To use this filter with other analyzers, you'll want to write an
+	/// Analyzer class that sets up the TokenStream chain as you want it.
+	/// To use this with LowerCaseTokenizer, for example, you'd write an
+	/// analyzer like this:
+	/// <p/>
+	/// <code>
+	/// class MyAnalyzer extends Analyzer {
+	///     public final TokenStream tokenStream(String fieldName, Reader reader) {
+	///          return new PorterStemFilter(new LowerCaseTokenizer(reader));
+	///     }
+	/// }
+	/// </code>
+	/// </summary>
+	public sealed class PorterStemFilter:TokenFilter
+	{
+		private readonly PorterStemmer stemmer;
+		private readonly ITermAttribute termAtt;
+		
+		public PorterStemFilter(TokenStream in_Renamed):base(in_Renamed)
+		{
+			stemmer = new PorterStemmer();
+            termAtt = AddAttribute<ITermAttribute>();
+		}
+		
+		public override bool IncrementToken()
+		{
+			if (!input.IncrementToken())
+				return false;
+			
+			if (stemmer.Stem(termAtt.TermBuffer(), 0, termAtt.TermLength()))
+				termAtt.SetTermBuffer(stemmer.ResultBuffer, 0, stemmer.ResultLength);
+			return true;
+		}
+	}
+}
+\ No newline at end of file