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From sergiu gordea <gser...@ifit.uni-klu.ac.at>
Subject Re: *term search
Date Thu, 07 Oct 2004 09:55:06 GMT
iouli.golovatyi@group.novartis.com wrote:

>.. and here is the way to do it:
>(See attached file: SUPPOR~1.RAR)
>  
>

Hi all,

 I got from iouli the solution to enable prefix queries (*term). In fact 
you can find the solution in
lucene source, in QueryParser.jj is said in a comment how to  enable 
prefix queries.

I did so ... but I found a lot of bugs. If you  define WildTerm as

| <WILDTERM:  (<_TERM_CHAR> | ( [ "*", "?" ] ))* >

a lot of  constructions will be validated, and you will get a lot of 
errors ...
for example "----" and "+++++" are considered valid, * is considered 
valid, and they generate TooManyBooleanClausesExceptions,

I' not very good in creating regular expressions but I succesfully use 
the following construction ..

 | <WILDTERM:  (<_TERM_START_CHAR> (<_TERM_CHAR> | ( [ "*", "?" ] ))* )
                    | ( [ "*", "?" ] <_TERM_START_CHAR> (<_TERM_CHAR> | 
( [ "*", "?" ] ) )* ) >

Can anyone improve the construction and update the comment in 
QueryParser.jj?

  Thanks a lot,

  Sergiu

>
>
>                                                                                     
                    
>                      Erik Hatcher                                                   
                    
>                      <erik@ehatchersol        To:       "Lucene Users List"      
                       
>                      utions.com>               <lucene-user@jakarta.apache.org>
                         
>                                               cc:       (bcc: Iouli Golovatyi/X/GP/Novartis)
            
>                      08.09.2004 12:46         Subject:  Re: *term search            
                    
>                      Please respond to                                              
                    
>                      "Lucene Users            Category:       |-------------------------|
               
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>
>
>
>On Sep 8, 2004, at 6:26 AM, sergiu gordea wrote:
>  
>
>>I want to discuss a little problem, lucene doesn't support *Term like
>>queries.
>>    
>>
>
>First of all, this is untrue.  WildcardQuery itself most definitely
>supports wildcards at the beginning.
>
>  
>
>>I would like to use "*schreiben".
>>    
>>
>
>The dilemma you've encountered is that QueryParser prevents queries
>that begin with a wildcard.
>
>  
>
>>So my question is if there is a simple solution for implementing the
>>funtionality mentioned above.
>>Maybe subclassing one class and overwriting some methods will sufice.
>>    
>>
>
>It will require more than that in this case.  You will need to create a
>custom parser that allows the grammar you'd like.  Feel free to use the
>JavaCC source code to QueryParser as a basis of your customizations.
>
>             Erik
>
>
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