content: /**
   * 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.
   */
  package org.apache.solr.analysis;
  
  import java.io.IOException;
  import java.util.LinkedList;
  
  import org.apache.commons.codec.language.DoubleMetaphone;
  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.PositionIncrementAttribute;
  
  public final class DoubleMetaphoneFilter extends TokenFilter {
  
    private static final String TOKEN_TYPE = "DoubleMetaphone";
    
    private final LinkedList<State> remainingTokens = new LinkedList<State>();
    private final DoubleMetaphone encoder = new DoubleMetaphone();
    private final boolean inject;
    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    private final PositionIncrementAttribute posAtt = addAttribute(PositionIncrementAttribute.class);
  
    protected DoubleMetaphoneFilter(TokenStream input, int maxCodeLength, boolean inject) {
      super(input);
      this.encoder.setMaxCodeLen(maxCodeLength);
      this.inject = inject;
    }
  
    @Override
    public boolean incrementToken() throws IOException {
      for(;;) {
  
        if (!remainingTokens.isEmpty()) {
          // clearAttributes();  // not currently necessary
          restoreState(remainingTokens.removeFirst());
          return true;
        }
  
        if (!input.incrementToken()) return false;
  
        int len = termAtt.length();
        if (len==0) return true; // pass through zero length terms
        
        int firstAlternativeIncrement = inject ? 0 : posAtt.getPositionIncrement();
  
        String v = termAtt.toString();
        String primaryPhoneticValue = encoder.doubleMetaphone(v);
        String alternatePhoneticValue = encoder.doubleMetaphone(v, true);
  
        // a flag to lazily save state if needed... this avoids a save/restore when only
        // one token will be generated.
        boolean saveState=inject;
  
        if (primaryPhoneticValue!=null && primaryPhoneticValue.length() > 0 && !primaryPhoneticValue.equals(v)) {
          if (saveState) {
            remainingTokens.addLast(captureState());
          }
          posAtt.setPositionIncrement( firstAlternativeIncrement );
          firstAlternativeIncrement = 0;
          termAtt.setEmpty().append(primaryPhoneticValue);
          saveState = true;
        }
  
        if (alternatePhoneticValue!=null && alternatePhoneticValue.length() > 0
                && !alternatePhoneticValue.equals(primaryPhoneticValue)
                && !primaryPhoneticValue.equals(v)) {
          if (saveState) {
            remainingTokens.addLast(captureState());
            saveState = false;
          }
          posAtt.setPositionIncrement( firstAlternativeIncrement );
          termAtt.setEmpty().append(alternatePhoneticValue);
          saveState = true;
        }
  
        // Just one token to return, so no need to capture/restore
        // any state, simply return it.
        if (remainingTokens.isEmpty()) {
          return true;
        }
  
        if (saveState) {
          remainingTokens.addLast(captureState());
        }
      }
    }
  
    @Override
    public void reset() throws IOException {
      input.reset();
      remainingTokens.clear();
    }
  }
  