http://lucene.apache.org/lucene-parent/lucene-queryparser: Lucene QueryParsers module (The Apache Software Foundation) 
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 * 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
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 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.lucene.queryparser.ext;

import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.search.Query;


This class represents an extension base class to the Lucene standard QueryParser. The QueryParser is generated by the JavaCC parser generator. Changing or adding functionality or syntax in the standard query parser requires changes to the JavaCC source file. To enable extending the standard query parser without changing the JavaCC sources and re-generate the parser the ParserExtension can be customized and plugged into an instance of ExtendableQueryParser, a direct subclass of QueryParser. 
See Also:
/**
 * This class represents an extension base class to the Lucene standard
 * {@link org.apache.lucene.queryparser.classic.QueryParser}. The
 * {@link org.apache.lucene.queryparser.classic.QueryParser} is generated by the JavaCC
 * parser generator. Changing or adding functionality or syntax in the standard
 * query parser requires changes to the JavaCC source file. To enable extending
 * the standard query parser without changing the JavaCC sources and re-generate
 * the parser the {@link ParserExtension} can be customized and plugged into an
 * instance of {@link ExtendableQueryParser}, a direct subclass of
 * {@link org.apache.lucene.queryparser.classic.QueryParser}.
 * 
 * @see Extensions
 * @see ExtendableQueryParser
 */
public abstract class ParserExtension {

  
Processes the given ExtensionQuery and returns a corresponding Query instance. Subclasses must either return a Query instance or raise a ParseException. This method must not return null.

Params:
  • query – 
         the extension query
Throws:
Returns:a new query instance
/**
   * Processes the given {@link ExtensionQuery} and returns a corresponding
   * {@link Query} instance. Subclasses must either return a {@link Query}
   * instance or raise a {@link ParseException}. This method must not return
   * <code>null</code>.
   * 
   * @param query
   *          the extension query
   * @return a new query instance
   * @throws ParseException
   *           if the query can not be parsed.
   */
  public abstract Query parse(final ExtensionQuery query) throws ParseException;

}