Horton

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

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: David Steele <david@pgmasters.net>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2020-01-22T19:57:01Z
Lists: pgsql-hackers 
On Wed, Jan 22, 2020 at 2:26 PM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
> I'm not sure I see the point of keeping json.h split from jsonapi.h.  It
> seems to me that you could move back all the contents from jsonapi.h
> into json.h, and everything would work just as well.  (Evidently the
> Datum in JsonEncodeDateTime's proto is problematic ... perhaps putting
> that prototype in jsonfuncs.h would work.)
>
> I don't really object to your 0001 patch as posted, though.

The goal is to make it possible to use the JSON parser in the
frontend, and we can't do that if the header files that would have to
be included on the frontend side rely on things that only work in the
backend. As written, the patch series leaves json.h with a dependency
on Datum, so the stuff that it leaves in jsonapi.h (which is intended
to be the header that gets moved to src/common and included by
frontend code) can't be merged with it.

Now, we could obviously rearrange that. I don't think any of the file
naming here is great. But I think we probably want, as far as
possible, for the code in FOO.c to correspond to the prototypes in
FOO.h. What I'm thinking we should work towards is:

json.c/h - support for the 'json' data type
jsonb.c/h - support for the 'jsonb' data type
jsonfuncs.c/h - backend code that doesn't fit in either of the above
jsonapi.c/h - lexing/parsing code that can be used in either the
frontend or the backend

I'm not wedded to that. It just looks like the most natural thing from
where we are now.

Thoughts?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Add jsonapi.c to Mkvcbuild.pm's @pgcommonallfiles.

  2. Move jsonapi.c and jsonapi.h to src/common.

  3. Move some code from jsonapi.c to jsonfuncs.c.

  4. Adjust pg_parse_json() so that it does not directly ereport().

  5. Remove jsonapi.c's lex_accept().

  6. Split JSON lexer/parser from 'json' data type support.

  7. Rationalize code placement between wchar.c, encnames.c, and mbutils.c.

  8. Move wchar.c and encnames.c to src/common/.

  9. Update header comments for wchar.c and encnames.c.

  10. Make StringInfo available to frontend code.

  11. Use SASLprep to normalize passwords for SCRAM authentication.