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 java.io.IOException;
  import java.util.Set;
  
  import org.apache.lucene.analysis.tokenattributes.KeywordAttribute;
  import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
  import org.apache.lucene.util.Version;
  
  /**
   * Marks terms as keywords via the {@link KeywordAttribute}. Each token
   * contained in the provided is marked as a keyword by setting
   * {@link KeywordAttribute#setKeyword(boolean)} to <code>true</code>.
   * 
   * @see KeywordAttribute
   */
  public final class KeywordMarkerFilter extends TokenFilter {
  
    private final KeywordAttribute keywordAttr = addAttribute(KeywordAttribute.class);
    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    private final CharArraySet keywordSet;
  
    /**
     * Create a new KeywordMarkerFilter, that marks the current token as a
     * keyword if the tokens term buffer is contained in the given set via the
     * {@link KeywordAttribute}.
     * 
     * @param in
     *          TokenStream to filter
     * @param keywordSet
     *          the keywords set to lookup the current termbuffer
     */
    public KeywordMarkerFilter(final TokenStream in,
        final CharArraySet keywordSet) {
      super(in);
      this.keywordSet = keywordSet;
    }
  
    /**
     * Create a new KeywordMarkerFilter, that marks the current token as a
     * keyword if the tokens term buffer is contained in the given set via the
     * {@link KeywordAttribute}.
     * 
     * @param in
     *          TokenStream to filter
     * @param keywordSet
     *          the keywords set to lookup the current termbuffer
     */
    public KeywordMarkerFilter(final TokenStream in, final Set<?> keywordSet) {
      this(in, keywordSet instanceof CharArraySet ? (CharArraySet) keywordSet
          : CharArraySet.copy(Version.LUCENE_31, keywordSet));
    }
  
    @Override
    public final boolean incrementToken() throws IOException {
      if (input.incrementToken()) {
        if (keywordSet.contains(termAtt.buffer(), 0, termAtt.length())) { 
          keywordAttr.setKeyword(true);
        }
        return true;
      } else {
        return false;
      }
    }
  }
  