Date: Thu, 22 Oct 2015 18:49:28 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>,
 Thomas Munro <thomas.munro@enterprisedb.com>,
 Jeff Janes <jeff.janes@gmail.com>,
 Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Making tab-complete.c easier to maintain
Message-ID: <20151022214928.GS3391@alvherre.pgsql>
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Tom Lane wrote:

> What I would like is to find a way to auto-generate basically this entire
> file from gram.y.  That would imply going over to something at least
> somewhat parser-based, instead of the current way that is more or less
> totally ad-hoc.  That would be a very good thing though, because the
> current way gives wrong answers not-infrequently, even discounting cases
> that it's simply not been taught about.

I did discuss exactly this topic with Thomas a month ago or so in
private email, and our conclusion was that it would be a really neat
project but a lot more effort than this patch.  And after skimming over
the patch back then, I think this is well worth the reduced maintenance
effort.

> I have no very good idea how to do that, though.  Bison does have a
> notion of which symbols are possible as the next symbol at any given
> parse point, but it doesn't really make that accessible.  There's a lack
> of cooperation on the readline side too: we'd need to be able to see the
> whole query buffer not just the current line.

At the current pace, a project like this might take years to
turn into a real patch.  My own vote is for applying this for the time
being.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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