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From Roman Chyla <roman.ch...@gmail.com>
Subject How to plug a new ANTLR grammar
Date Tue, 13 Sep 2011 17:34:11 GMT
Hi,

The standard lucene/solr parsing is nice but not really flexible. I
saw questions and discussion about ANTLR, but unfortunately never a
working grammar, so... maybe you find this useful:
https://github.com/romanchyla/montysolr/tree/master/src/java/org/apache/lucene/queryParser/iqp/antlr

In the grammar, the parsing is completely abstracted from the Lucene
objects, and the parser is not mixed with Java code. At first it
produces structures like this:
https://svnweb.cern.ch/trac/rcarepo/raw-attachment/wiki/MontySolrQueryParser/index.html

But now I have a problem. I don't know if I should use query parsing
framework in contrib.

It seems that the qParser in contrib can use different parser
generators (the default JavaCC, but also ANTLR). But I am confused and
I don't understand this new queryParser from contrib. It is really
very confusing to me. Is there any benefit in trying to plug the ANTLR
tree into it? Because looking at the AST pictures, it seems that with
a relatively simple tree walker we could build the same queries as the
current standard lucene query parser. And it would be much simpler and
flexible. Does it bring something new? I have a feeling I miss
something...

Many thanks for help,

  Roman

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