content: package org.apache.solr.spelling;
  /**
   * 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.index.IndexReader;
  import org.apache.lucene.index.IndexWriterConfig;
  import org.apache.lucene.store.FSDirectory;
  import org.apache.solr.common.util.NamedList;
  import org.apache.solr.core.SolrCore;
  import org.apache.solr.search.SolrIndexSearcher;
  import org.apache.lucene.search.spell.HighFrequencyDictionary;
  
  import java.io.File;
  import java.io.IOException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * <p>
   * A spell checker implementation that loads words from Solr as well as arbitary Lucene indices.
   * </p>
   * 
   * <p>
   * Refer to <a href="http://wiki.apache.org/solr/SpellCheckComponent">SpellCheckComponent</a>
   * for more details.
   * </p>
   * 
   * @since solr 1.3
   **/
  public class IndexBasedSpellChecker extends AbstractLuceneSpellChecker {
    private static final Logger log = LoggerFactory.getLogger(IndexBasedSpellChecker.class);
  
    public static final String THRESHOLD_TOKEN_FREQUENCY = "thresholdTokenFrequency";
  
    protected float threshold;
    protected IndexReader reader;
  
    @Override
    public String init(NamedList config, SolrCore core) {
      super.init(config, core);
      threshold = config.get(THRESHOLD_TOKEN_FREQUENCY) == null ? 0.0f
              : (Float) config.get(THRESHOLD_TOKEN_FREQUENCY);
      initSourceReader();
      return name;
    }
  
    private void initSourceReader() {
      if (sourceLocation != null) {
        try {
          FSDirectory luceneIndexDir = FSDirectory.open(new File(sourceLocation));
          this.reader = IndexReader.open(luceneIndexDir);
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
    }
  
    @Override
    public void build(SolrCore core, SolrIndexSearcher searcher) {
      IndexReader reader = null;
      try {
        if (sourceLocation == null) {
          // Load from Solr's index
          reader = searcher.getReader();
        } else {
          // Load from Lucene index at given sourceLocation
          reader = this.reader;
        }
  
        // Create the dictionary
        dictionary = new HighFrequencyDictionary(reader, field,
            threshold);
        spellChecker.clearIndex();
        spellChecker.indexDictionary(dictionary, new IndexWriterConfig(core.getSolrConfig().luceneMatchVersion, null), false);
  
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  
    @Override
    protected IndexReader determineReader(IndexReader reader) {
      IndexReader result = null;
      if (sourceLocation != null) {
        result = this.reader;
      } else {
        result = reader;
      }
      return result;
    }
  
    @Override
    public void reload(SolrCore core, SolrIndexSearcher searcher) throws IOException {
      super.reload(core, searcher);
      //reload the source
      initSourceReader();
    }
  
    public float getThreshold() {
      return threshold;
    }
  }
  