content: /**
   * Copyright 2009 Alexander Kuznetsov 
   *
   * Licensed 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.
   */
  
  package org.apache.lucene.morphology.analyzer;
  
  import org.apache.lucene.analysis.TokenFilter;
  import org.apache.lucene.analysis.TokenStream;
  import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
  import org.apache.lucene.analysis.tokenattributes.KeywordAttribute;
  import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
  import org.apache.lucene.morphology.LuceneMorphology;
  
  import java.io.IOException;
  import java.util.Iterator;
  import java.util.List;
  
  
  public class MorphologyFilter extends TokenFilter {
      private LuceneMorphology luceneMorph;
      private Iterator<String> iterator;
      private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
      private final KeywordAttribute keywordAttr = addAttribute(KeywordAttribute.class);
      private final PositionIncrementAttribute position = addAttribute(PositionIncrementAttribute.class);
      private State state = null;
  
      public MorphologyFilter(TokenStream tokenStream, LuceneMorphology luceneMorph) {
          super(tokenStream);
          this.luceneMorph = luceneMorph;
      }
  
  
      final public boolean incrementToken() throws IOException {
          if (iterator != null) {
              if (iterator.hasNext()) {
                  restoreState(state);
                  position.setPositionIncrement(0);
                  termAtt.setEmpty().append(iterator.next());
                  return true;
              } else {
                  state = null;
                  iterator = null;
              }
          }
          while (true) {
              boolean b = input.incrementToken();
              if (!b) {
                  return false;
              }
              if (!keywordAttr.isKeyword() && termAtt.length() > 0) {
                  String s = new String(termAtt.buffer(), 0, termAtt.length());
                  if (luceneMorph.checkString(s)) {
                      List<String> forms = luceneMorph.getNormalForms(s);
                      if (forms.isEmpty()) {
                          continue;
                      } else if (forms.size() == 1) {
                          termAtt.setEmpty().append(forms.get(0));
                      } else {
                          state = captureState();
                          iterator = forms.iterator();
                          termAtt.setEmpty().append(iterator.next());
                      }
                  }
              }
              return true;
          }
      }
  
      @Override
      public void reset() throws IOException {
          super.reset();
          state = null;
          iterator = null;
      }
  }
  