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.lucene.analysis;
  
  import java.io.Reader;
  
  /**
   * CharStream adds {@link #correctOffset}
   * functionality over {@link Reader}.  All Tokenizers accept a
   * CharStream instead of {@link Reader} as input, which enables
   * arbitrary character based filtering before tokenization. 
   * The {@link #correctOffset} method fixed offsets to account for
   * removal or insertion of characters, so that the offsets
   * reported in the tokens match the character offsets of the
   * original Reader.
   */
  public abstract class CharStream extends Reader {
  
    /**
     * Called by CharFilter(s) and Tokenizer to correct token offset.
     *
     * @param currentOff offset as seen in the output
     * @return corrected offset based on the input
     */
    public abstract int correctOffset(int currentOff);
  }
  