Обсуждение: Re: How to build a new grammer for pg?

Hi,

On Tue, Aug 01, 2023 at 07:36:36PM +0800, jacktby wrote:
> <span style="font-family: Helvetica, Helvetica, 微软雅黑, 宋体;">Hi, I’m trying to develop a new grammar for pg, can
+you give me a code example to reference?</span><span>

It's unclear to me whether you want to entirely replace the flex/bison parser
with something else or just add some new bison rule.

If the latter, it really depends on what you change to achieve exactly.  I
guess you could just look at the gram.y git history until you find something
close enough to your use case and get inspiration from that.

On 2023-08-01 07:58, Julien Rouhaud wrote:
> On Tue, Aug 01, 2023 at 07:36:36PM +0800, jacktby wrote:
>> Hi, I’m trying to develop a new grammar for pg
> 
> It's unclear to me whether you want to entirely replace the flex/bison 
> parser
> with something else or just add some new bison rule.

Or express a grammar matching PG's in some other parser-generator
language, to enable some other tool to parse PG productions?

Regards,
-Chap

On 2023-08-01 07:58, Julien Rouhaud wrote:

On Tue, Aug 01, 2023 at 07:36:36PM +0800, jacktby wrote:

Hi, I’m trying to develop a new grammar for pg

It's unclear to me whether you want to entirely replace the flex/bison parser
with something else or just add some new bison rule.

Or express a grammar matching PG's in some other parser-generator
language, to enable some other tool to parse PG productions?

Or to enable some language other than SQL (QUEL anyone?)

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com

I would look at how Babelfish DB did it when adding SQL Server compatibility

https://babelfishpg.org/ and https://github.com/babelfish-for-postgresql/

another source to inspect could be
https://github.com/IvorySQL/IvorySQL for "oracle compatible
PostgreSQL"

On Tue, Aug 1, 2023 at 10:07 PM Jonah H. Harris <jonah.harris@gmail.com> wrote:
>
> On Tue, Aug 1, 2023 at 3:45 PM Andrew Dunstan <andrew@dunslane.net> wrote:
>>
>> Or to enable some language other than SQL (QUEL anyone?)
>
>
> A few years ago, I got a minimal POSTQUEL working again to release as a patch for April Fools' Day, which I never
did.I should dig that up somewhere :) 
>
> Anyway, as far as OP's original question regarding replacing the grammar, there are a couple of such implementations
floatingaround that have done that. But, I actually think the pluggable parser patches were good examples of how to
integratea replacement parser that generates the expected parse tree nodes for anyone who wants to do their own custom
parser.See Julien Rouhaud's SQLOL in the "Hook for extensible parsing" thread and Jim Mlodgenski's "Parser Hook"
thread.
>
> --
> Jonah H. Harris
>