Re: jsonpath

On Tue, Mar 19, 2019 at 8:10 PM Alexander Korotkov
<a(dot)korotkov(at)postgrespro(dot)ru> wrote:
> On Sun, Mar 17, 2019 at 6:03 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)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