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From Andrew Gilmartin <and...@andrewgilmartin.com>
Subject Re: Custom Query Syntax/Parser
Date Mon, 28 Jan 2013 16:42:36 GMT
Uwe Schindler wrote:

> there is no need to extend Lucene's QueryParser. Lucene by 
> itself does not need a Query Parser at all and it does not 
> use it, it is just a convenience class. If you have worked 
> with Antlr to generate a grammar, just use it and build 
> the final org.apache.lucene.search.Query in your code.

I would only add to that is that you might also consider being able to apply a Visitor pattern
to your resulting query. I do this so that applying query transformations -- like broadening
terms (w/ a lower boost) or adding bigrams -- is done consistently across all expression syntaxes.

When I first started using Lucene, Lucene's Query classes where not suitable for use with
the Visitor pattern and so I created my own query class equivalants and other more specialized
ones. Lucene's classes might have changed since then (I do not know), but I continue to use
my own set and several visitor implementations. The final visitor that I apply is the "convert
to Lucene query" transformation.

-- Andrew

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