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;
  
  /** A TokenFilter is a TokenStream whose input is another TokenStream.
    <p>
    This is an abstract class; subclasses must override {@link #incrementToken()}.
    @see TokenStream
    */
  public abstract class TokenFilter extends TokenStream {
    /** The source of tokens for this filter. */
    protected final TokenStream input;
  
    /** Construct a token stream filtering the given input. */
    protected TokenFilter(TokenStream input) {
      super(input);
      this.input = input;
    }
    
    /** Performs end-of-stream operations, if any, and calls then <code>end()</code> on the
     * input TokenStream.<p/> 
     * <b>NOTE:</b> Be sure to call <code>super.end()</code> first when overriding this method.*/
    @Override
    public void end() throws IOException {
      input.end();
    }
    
    /** Close the input TokenStream. */
    @Override
    public void close() throws IOException {
      input.close();
    }
  
    /** Reset the filter as well as the input TokenStream. */
    @Override
    public void reset() throws IOException {
      input.reset();
    }
  }
  