content: package org.apache.lucene.search;
  
  /**
   * 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.Iterator;
  import java.util.Set;
  import java.util.TreeSet;
  
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.index.Term;
  import org.apache.lucene.index.TermDocs;
  import org.apache.lucene.util.FixedBitSet;
  
  /**
   * Constructs a filter for docs matching any of the terms added to this class. 
   * Unlike a RangeFilter this can be used for filtering on multiple terms that are not necessarily in 
   * a sequence. An example might be a collection of primary keys from a database query result or perhaps 
   * a choice of "category" labels picked by the end user. As a filter, this is much faster than the 
   * equivalent query (a BooleanQuery with many "should" TermQueries)
   *
   */
  public class TermsFilter extends Filter
  {
  	Set<Term> terms=new TreeSet<Term>();
  	
  	/**
  	 * Adds a term to the list of acceptable terms   
  	 * @param term
  	 */
  	public void addTerm(Term term)
  	{
  		terms.add(term);
  	}
  	
  /* (non-Javadoc)
     * @see org.apache.lucene.search.Filter#getDocIdSet(org.apache.lucene.index.IndexReader)
  	 */
    @Override
    public DocIdSet getDocIdSet(IndexReader reader) throws IOException
  	{
      FixedBitSet result=new FixedBitSet(reader.maxDoc());
          TermDocs td = reader.termDocs();
          try
          {
              for (Iterator<Term> iter = terms.iterator(); iter.hasNext();)
              {
                  Term term = iter.next();
                  td.seek(term);
                  while (td.next())
                  {
                      result.set(td.doc());
                  }
              }
          }
          finally
          {
              td.close();
          }
          return result;
  	}
  	
  	@Override
  	public boolean equals(Object obj)
  	{
  		if(this == obj)
  			return true;
  		if((obj == null) || (obj.getClass() != this.getClass()))
  				return false;
  		TermsFilter test = (TermsFilter)obj;
  		return (terms == test.terms ||
  					 (terms != null && terms.equals(test.terms)));
  	}
  
  	@Override
  	public int hashCode()
  	{
  		int hash=9;
  		for (Iterator<Term> iter = terms.iterator(); iter.hasNext();)
  		{
  			Term term = iter.next();
  			hash = 31 * hash + term.hashCode();			
  		}
  		return hash;
  	}
  	
  }
  