package org.apache.maven.index.context;
   
   /*
    * 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 java.io.Reader;
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.analysis.CharTokenizer;
  import org.apache.lucene.analysis.TokenStream;
  import org.apache.lucene.analysis.standard.StandardAnalyzer;
  import org.apache.lucene.util.Version;
  import org.apache.maven.index.ArtifactInfo;
  
  /**
   * A Nexus specific <a
   * href="http://lucene.apache.org/java/2_4_0/api/core/org/apache/lucene/analysis/Analyzer.html">Lucene Analyzer</a> used
   * to produce legacy index transfer format
   * 
   * @author Jason van Zyl
   */
  public final class NexusLegacyAnalyzer
      extends Analyzer
  {
      private static Analyzer DEFAULT_ANALYZER = new StandardAnalyzer( Version.LUCENE_30 );
  
      @Override
      public TokenStream tokenStream( String field, final Reader reader )
      {
          if ( !isTextField( field ) )
          {
              return new CharTokenizer( reader )
              {
                  @Override
                  protected boolean isTokenChar( char c )
                  {
                      return Character.isLetterOrDigit( c );
                  }
  
                  @Override
                  protected char normalize( char c )
                  {
                      return Character.toLowerCase( c );
                  }
              };
          }
          else
          {
              return DEFAULT_ANALYZER.tokenStream( field, reader );
          }
      }
  
      @Override
      public TokenStream reusableTokenStream( String field, Reader reader )
          throws IOException
      {
          if ( !isTextField( field ) )
          {
              return new CharTokenizer( reader )
              {
                  @Override
                  protected boolean isTokenChar( char c )
                  {
                      return Character.isLetterOrDigit( c );
                  }
  
                  @Override
                  protected char normalize( char c )
                  {
                      return Character.toLowerCase( c );
                  }
              };
          }
          else
          {
              return DEFAULT_ANALYZER.reusableTokenStream( field, reader );
          }
      }
  
      protected boolean isTextField( String field )
      {
          return ArtifactInfo.NAME.equals( field ) || ArtifactInfo.DESCRIPTION.equals( field )
             || ArtifactInfo.NAMES.equals( field );
 
     }
 
 }