Index: src/test/org/apache/lucene/analysis/TestTurkishLowerCaseFilter.java
===================================================================
--- src/test/org/apache/lucene/analysis/TestTurkishLowerCaseFilter.java	(revision 0)
+++ src/test/org/apache/lucene/analysis/TestTurkishLowerCaseFilter.java	(revision 0)
@@ -0,0 +1,34 @@
+package org.apache.lucene.analysis;
+
+/**
+ * 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.
+ */
+
+import org.apache.lucene.analysis.tokenattributes.TermAttribute;
+import org.apache.lucene.util.Version;
+
+import java.io.StringReader;
+
+public class TestTurkishLowerCaseFilter extends BaseTokenStreamTestCase {
+  
+  public void testTurkishLowerCaseFilter() throws Exception {
+    TokenStream stream = new WhitespaceTokenizer(
+        new StringReader("\u0130STANBUL \u0130ZM\u0130R ISPARTA"));
+    TurkishLowerCaseFilter filter = new TurkishLowerCaseFilter(Version.LUCENE_30, stream);
+	assertTokenStreamContents(filter, new String[] {"istanbul", "izmir", "\u0131sparta",});      
+  }
+
+}
Index: src/java/org/apache/lucene/analysis/TurkishLowerCaseFilter.java
===================================================================
--- src/java/org/apache/lucene/analysis/TurkishLowerCaseFilter.java	(revision 0)
+++ src/java/org/apache/lucene/analysis/TurkishLowerCaseFilter.java	(revision 0)
@@ -0,0 +1,69 @@
+package org.apache.lucene.analysis;
+
+/**
+ * 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.
+ */
+
+import java.io.IOException;
+
+import org.apache.lucene.analysis.tokenattributes.TermAttribute;
+import org.apache.lucene.util.CharacterUtils;
+import org.apache.lucene.util.Version;
+
+/**
+ * Normalizes Turkish token text to lower case.
+ * <a name="version"/>
+ * <p>You must specify the required {@link Version}
+ * compatibility when creating TurkishLowerCaseFilter:
+ * <ul>
+ *   <li> As of 3.1, supplementary characters are properly lowercased.
+ * </ul>
+ * @since lucene 3.1
+ */
+public final class TurkishLowerCaseFilter extends TokenFilter {
+  private final CharacterUtils charUtils;
+  private final int LATIN_CAPITAL_LETTER_I = 0x0049;
+  private final int LATIN_SMALL_LETTER_DOTLESS_I = 0x0131;
+
+  /**
+   * Create a new TurkishLowerCaseFilter, that normalizes Turkish token text to lower case.
+   * 
+   * @param matchVersion See <a href="#version">above</a>
+   * @param in TokenStream to filter
+   */
+  public TurkishLowerCaseFilter(Version matchVersion, TokenStream in) {
+    super(in);
+    termAtt = addAttribute(TermAttribute.class);
+    charUtils = CharacterUtils.getInstance(matchVersion);
+  }
+  
+  private TermAttribute termAtt;
+  
+  @Override
+  public final boolean incrementToken() throws IOException {
+    if (input.incrementToken()) {
+      final char[] buffer = termAtt.termBuffer();
+      final int length = termAtt.termLength();
+      for (int i = 0; i < length;) {
+       i += Character.toChars(
+               Character.toLowerCase(
+                   charUtils.codePointAt(buffer, i) == LATIN_CAPITAL_LETTER_I ? LATIN_SMALL_LETTER_DOTLESS_I : charUtils.codePointAt(buffer, i)), buffer, i);
+      }
+      return true;
+    } else
+      return false;
+  }
+}