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Pig, mail # user - Adding keywords to Pig Latin (Was: Question about UDFs and tuple ordering)


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Brian Stempin 2012-10-09, 20:54
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Re: Adding keywords to Pig Latin (Was: Question about UDFs and tuple ordering)
Gianmarco De Francisci Mo... 2012-10-09, 21:40
Hi,
one grammar is responsible for lexing (tokenization), the second one for
parsing and the last one for generating the plan from a tree grammar (the
AST output of the parsing).
These are the main ones, but there are also some "minor" ones like AST
validator or AST printer.

If you had to add a keyword you would at least need to modify the
QueryLexer, most likely also the QueryParser, possibly also the
LogicalPlanGenerator (and LogicalPlanBuilder.java as well).

Hope this helps.

Cheers,
--
Gianmarco

On Tue, Oct 9, 2012 at 1:54 PM, Brian Stempin <[EMAIL PROTECTED]>wrote:

> I've taken some time to understand how a Logical Plan progresses to a
> Physical and MR Plan (thanks for the boost, Alan!)
>
> My next question is centered around Logical Plan generation.  If one were
> to add a new keyword (sticking with the theme in my last message, say,
> SUPERSPECIALJOIN), that keyword would have to be added into the grammar
> files.  Perhaps this isn't obvious to me because I'm not an ANTLR user
> (learning), but what is each grammar file responsible for?
>
> Thanks,
> Brian
>
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