Re: jsonpath

On Tue, Mar 19, 2019 at 8:10 PM Alexander Korotkov
<a.korotkov@postgrespro.ru> wrote:
> On Sun, Mar 17, 2019 at 6:03 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
> > > Why are we installing the jsonpath_gram.h file? It's not going to be
> > > used by anything else, is it? TBH, I'm not sure I see why we're
> > > installing the scanner.h file either.
> >
> > As near as I can see, jsonpath_gram.h and jsonpath_scanner.h exist only
> > for communication between jsonpath_gram.y and jsonpath_scan.l.  Maybe
> > we'd be better off handling that need by compiling the .l file as part
> > of the .y file, as we used to do with the core lexer and still do with
> > several others (cf comments for commit 72b1e3a21); then we wouldn't
> > even have to generate these files much less install them.
> >
> > A quick look at jsonpath_scan.c shows that it's pretty innocent of
> > the tricks we've learned over the years for flex/bison portability;
> > in particular I see that it's #including <stdio.h> before postgres.h,
> > which is a no-no.  So that whole area needs more review anyway.
>
> Attached patch is getting rid of jsonpath_gram.h.  Would like to see
> results of http://commitfest.cputube.org/ before committing, because
> I'm not available to test this of windows machine.  There would be
> further patches rearranging jsonpath_gram.y and jsonpath_scan.l.

Attaches patches improving jsonpath parser.  First one introduces
cosmetic changes, while second gets rid of backtracking.  I'm also
planning to add high-level comment for both grammar and lexer.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company