src/java/org/apache/lucene/analysis/Analyzer.java

package org.apache.lucene.analysis;

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import java.io.Reader;

/** An Analyzer builds TokenStreams, which analyze text.  It thus represents a
 *  policy for extracting index terms from text.
 *  <p>
 *  Typical implementations first build a Tokenizer, which breaks the stream of
 *  characters from the Reader into raw Tokens.  One or more TokenFilters may
 *  then be applied to the output of the Tokenizer.
 *  <p>
 *  WARNING: You must override one of the methods defined by this class in your
 *  subclass or the Analyzer will enter an infinite loop.
 */
abstract public class Analyzer {
  /** Creates a TokenStream which tokenizes all the text in the provided
    Reader.  Default implementation forwards to tokenStream(Reader) for 
    compatibility with older version.  Override to allow Analyzer to choose 
    strategy based on document and/or field.  Must be able to handle null
    field name for backward compatibility. */
  public TokenStream tokenStream(String fieldName, Reader reader)
  {
	  // implemented for backward compatibility
	  return tokenStream(reader);
  }
  
  /** Creates a TokenStream which tokenizes all the text in the provided
   *  Reader.  Provided for backward compatibility only.
   * @deprecated use tokenStream(String, Reader) instead.
   * @see #tokenStream(String, Reader)
   */
  public TokenStream tokenStream(Reader reader)
  {
	  return tokenStream(null, reader);
  }
}