Re: Railroad diagrams, a-la sqlite

On Sat, 2010-07-17 at 10:02 +0300, Hannu Krosing wrote:
> On Sat, 2010-07-17 at 08:30 +0300, Heikki Linnakangas wrote:
> > On 17/07/10 07:33, Steve Atkins wrote:
> > > Has everyone seen the "railroad diagrams" sqlite use in their docs? http://www.sqlite.org/lang_createindex.html , as one example.
> > >
> > > Would it be nice to have the same sort of format in the postgresql docs? (Yeah, I'm volunteering, if people think they're a useful thing, 'cos I think they'd add a lot to our documentation.)
> >
> > That would be nice. It would have to be automatically generated from the
> > syntax descriptions we already have, otherwise it'd be unmaintainable.
> > Also, the text representation would have to still be there in an alt tag
> > - I note that the the sqlite docs don't have that.
> >
> > Any idea how those sqlite images are generated?
>
> I have used this:
>
> http://www.informatik.uni-freiburg.de/~thiemann/haskell/ebnf2ps/
>
> to make railroad diagrams from postgresql lex/yacc sources a few years
> ago, when looking into adding WITH support to pg.
>
> As it takes extended BNF as input i had to convert pg's lex+yacc into
> eBNF, which IIRC I did using some python scripts + manual tweaking.

Now it's readme says it does support yacc as one of input formats, so it
may be a lot simpler .

>
> > --
> > Heikki Linnakangas
> > EnterpriseDB http://www.enterprisedb.com
> >
>
>