content: 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.document.Fieldable;
  
  import java.io.Reader;
  import java.io.IOException;
  import java.util.Map;
  import java.util.HashMap;
  
  /**
   * This analyzer is used to facilitate scenarios where different
   * fields require different analysis techniques.  Use the Map
   * argument in {@link #PerFieldAnalyzerWrapper(Analyzer, java.util.Map)}
   * to add non-default analyzers for fields.
   * 
   * <p>Example usage:
   * 
   * <pre>
   *   Map analyzerPerField = new HashMap();
   *   analyzerPerField.put("firstname", new KeywordAnalyzer());
   *   analyzerPerField.put("lastname", new KeywordAnalyzer());
   *
   *   PerFieldAnalyzerWrapper aWrapper =
   *      new PerFieldAnalyzerWrapper(new StandardAnalyzer(), analyzerPerField);
   * </pre>
   * 
   * <p>In this example, StandardAnalyzer will be used for all fields except "firstname"
   * and "lastname", for which KeywordAnalyzer will be used.
   * 
   * <p>A PerFieldAnalyzerWrapper can be used like any other analyzer, for both indexing
   * and query parsing.
   */
  public final class PerFieldAnalyzerWrapper extends Analyzer {
    private final Analyzer defaultAnalyzer;
    private final Map<String,Analyzer> analyzerMap = new HashMap<String,Analyzer>();
  
  
    /**
     * Constructs with default analyzer.
     *
     * @param defaultAnalyzer Any fields not specifically
     * defined to use a different analyzer will use the one provided here.
     */
    public PerFieldAnalyzerWrapper(Analyzer defaultAnalyzer) {
      this(defaultAnalyzer, null);
    }
    
    /**
     * Constructs with default analyzer and a map of analyzers to use for 
     * specific fields.
     *
     * @param defaultAnalyzer Any fields not specifically
     * defined to use a different analyzer will use the one provided here.
     * @param fieldAnalyzers a Map (String field name to the Analyzer) to be 
     * used for those fields 
     */
    public PerFieldAnalyzerWrapper(Analyzer defaultAnalyzer, 
        Map<String,Analyzer> fieldAnalyzers) {
      this.defaultAnalyzer = defaultAnalyzer;
      if (fieldAnalyzers != null) {
        analyzerMap.putAll(fieldAnalyzers);
      }
    }
    
  
    /**
     * Defines an analyzer to use for the specified field.
     *
     * @param fieldName field name requiring a non-default analyzer
     * @param analyzer non-default analyzer to use for field
     * @deprecated Changing the Analyzer for a field after instantiation prevents
     *             reusability.  Analyzers for fields should be set during construction.
     */
    @Deprecated
    public void addAnalyzer(String fieldName, Analyzer analyzer) {
      analyzerMap.put(fieldName, analyzer);
    }
  
    @Override
    public TokenStream tokenStream(String fieldName, Reader reader) {
      Analyzer analyzer = analyzerMap.get(fieldName);
      if (analyzer == null) {
        analyzer = defaultAnalyzer;
      }
  
      return analyzer.tokenStream(fieldName, reader);
    }
    
    @Override
    public TokenStream reusableTokenStream(String fieldName, Reader reader) throws IOException {
      Analyzer analyzer = analyzerMap.get(fieldName);
      if (analyzer == null)
        analyzer = defaultAnalyzer;
  
      return analyzer.reusableTokenStream(fieldName, reader);
    }
    
    /** Return the positionIncrementGap from the analyzer assigned to fieldName */
    @Override
    public int getPositionIncrementGap(String fieldName) {
      Analyzer analyzer = analyzerMap.get(fieldName);
      if (analyzer == null)
        analyzer = defaultAnalyzer;
      return analyzer.getPositionIncrementGap(fieldName);
    }
  
    /** Return the offsetGap from the analyzer assigned to field */
    @Override
    public int getOffsetGap(Fieldable field) {
      Analyzer analyzer = analyzerMap.get(field.name());
      if (analyzer == null)
        analyzer = defaultAnalyzer;
      return analyzer.getOffsetGap(field);
    }
    
    @Override
    public String toString() {
      return "PerFieldAnalyzerWrapper(" + analyzerMap + ", default=" + defaultAnalyzer + ")";
    }
  }
  