Re: making the backend's json parser work in frontend code

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> ... However, I decided to spend today doing some further
> investigation of an alternative approach, namely making the backend's
> existing JSON parser work in frontend code as well. I did not solve
> all the problems there, but I did come up with some patches which I
> think would be worth committing on independent grounds, and I think
> the whole series is worth posting. So here goes.

In general, if we can possibly get to having one JSON parser in
src/common, that seems like an obviously better place to be than
having two JSON parsers. So I'm encouraged that it might be
feasible after all.

> 0001 moves wchar.c from src/backend/utils/mb to src/common. Unless I'm
> missing something, this seems like an overdue cleanup.

FWIW, I've been wanting to do that for awhile. I've not studied
your patch, but +1 for the idea. We might also need to take a
hard look at mbutils.c to see if any of that code can/should move.

> Since I wrote my very first email complaining about the difficulty of
> making the backend's JSON parser work in a frontend environment, one
> obstacle has been knocked down: StringInfo is now available in
> front-end code (commit 26aaf97b683d6258c098859e6b1268e1f5da242f). The
> remaining problems (that I know about) have to do with error reporting
> and multibyte character support; a read of the patches is suggested
> for those wanting further details.

The patch I just posted at <2863(dot)1579127649(at)sss(dot)pgh(dot)pa(dot)us> probably
affects this in small ways, but not anything major.

regards, tom lane