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 org.apache.lucene.util.AttributeSource;
  
  import java.io.Reader;
  import java.io.IOException;
  
  /** A Tokenizer is a TokenStream whose input is a Reader.
    <p>
    This is an abstract class; subclasses must override {@link #incrementToken()}
    <p>
    NOTE: Subclasses overriding {@link #incrementToken()} must
    call {@link AttributeSource#clearAttributes()} before
    setting attributes.
   */
  public abstract class Tokenizer extends TokenStream {
    /** The text source for this Tokenizer. */
    protected Reader input;
  
    /** Construct a tokenizer with null input. */
    protected Tokenizer() {}
    
    /** Construct a token stream processing the given input. */
    protected Tokenizer(Reader input) {
      this.input = CharReader.get(input);
    }
    
    /** Construct a tokenizer with null input using the given AttributeFactory. */
    protected Tokenizer(AttributeFactory factory) {
      super(factory);
    }
  
    /** Construct a token stream processing the given input using the given AttributeFactory. */
    protected Tokenizer(AttributeFactory factory, Reader input) {
      super(factory);
      this.input = CharReader.get(input);
    }
  
    /** Construct a token stream processing the given input using the given AttributeSource. */
    protected Tokenizer(AttributeSource source) {
      super(source);
    }
  
    /** Construct a token stream processing the given input using the given AttributeSource. */
    protected Tokenizer(AttributeSource source, Reader input) {
      super(source);
      this.input = CharReader.get(input);
    }
    
    /** By default, closes the input Reader. */
    @Override
    public void close() throws IOException {
      if (input != null) {
        input.close();
        // LUCENE-2387: don't hold onto Reader after close, so
        // GC can reclaim
        input = null;
      }
    }
    
    /** Return the corrected offset. If {@link #input} is a {@link CharStream} subclass
     * this method calls {@link CharStream#correctOffset}, else returns <code>currentOff</code>.
     * @param currentOff offset as seen in the output
     * @return corrected offset based on the input
     * @see CharStream#correctOffset
     */
    protected final int correctOffset(int currentOff) {
      return (input instanceof CharStream) ? ((CharStream) input).correctOffset(currentOff) : currentOff;
    }
  
    /** Expert: Reset the tokenizer to a new reader.  Typically, an
     *  analyzer (in its reusableTokenStream method) will use
     *  this to re-use a previously created tokenizer. */
    public void reset(Reader input) throws IOException {
      this.input = input;
    }
  }
  
  