content: package org.apache.lucene.search.spell;
  
  /**
   * 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 java.util.Iterator;
  
  import org.apache.lucene.index.TermEnum;
  import org.apache.lucene.index.Term;
  import org.apache.lucene.util.StringHelper;
  
  import java.io.*;
  
  /**
   * Lucene Dictionary: terms taken from the given field
   * of a Lucene index.
   *
   * When using IndexReader.terms(Term) the code must not call next() on TermEnum
   * as the first call to TermEnum, see: http://issues.apache.org/jira/browse/LUCENE-6
   *
   *
   *
   */
  public class LuceneDictionary implements Dictionary {
    private IndexReader reader;
    private String field;
  
    public LuceneDictionary(IndexReader reader, String field) {
      this.reader = reader;
      this.field = StringHelper.intern(field);
    }
  
    public final Iterator<String> getWordsIterator() {
      return new LuceneIterator();
    }
  
  
    final class LuceneIterator implements Iterator<String> {
      private TermEnum termEnum;
      private Term actualTerm;
      private boolean hasNextCalled;
  
      LuceneIterator() {
        try {
          termEnum = reader.terms(new Term(field));
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
  
      public String next() {
        if (!hasNextCalled) {
          hasNext();
        }
        hasNextCalled = false;
  
        try {
          termEnum.next();
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
  
        return (actualTerm != null) ? actualTerm.text() : null;
      }
  
      public boolean hasNext() {
        if (hasNextCalled) {
          return actualTerm != null;
        }
        hasNextCalled = true;
  
        actualTerm = termEnum.term();
  
        // if there are no words return false
        if (actualTerm == null) {
          return false;
        }
  
        String currentField = actualTerm.field();
  
        // if the next word doesn't have the same field return false
        if (currentField != field) {
          actualTerm = null;
          return false;
        }
  
        return true;
      }
  
      public void remove() {
        throw new UnsupportedOperationException();
      }
    }
  }
  