Horton

Re: pure parsers and reentrant scanners

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: Heikki Linnakangas <hlinnaka@iki.fi>, Andreas Karlsson <andreas@proxel.se>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-01-08T09:53:57Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Return yyparse() result not via global variable

  2. Remove flex version checks

  3. Drop warning-free support for Flex 2.5.35

  4. plpgsql: pure parser and reentrant scanner

  5. flex code modernization: Replace YY_EXTRA_TYPE define with flex option

  6. guc: reentrant scanner

  7. jsonpath scanner: reentrant scanner

  8. syncrep parser: pure parser and reentrant scanner

  9. replication parser: pure parser and reentrant scanner

  10. bootstrap: pure parser and reentrant scanner

  11. Small whitespace improvement

  12. Prevent redeclaration of typedef yyscan_t

  13. seg: pure parser and reentrant scanner

  14. cube: pure parser and reentrant scanner

On 27.12.24 10:19, Heikki Linnakangas wrote:
> On 26/12/2024 20:27, Peter Eisentraut wrote:
>> On 22.12.24 22:43, Andreas Karlsson wrote:
>>> On 12/19/24 9:57 PM, Peter Eisentraut wrote:
>>>> Here is an updated patch set on top of what has been committed so 
>>>> far, with all the issues you pointed out addressed.
>>>
>>> Other than the discussion of how old versions of flex we should 
>>> support I think this set of patches is ready to be committed. I 
>>> looked at it again and everything looks good.
>>
>> I have committed these except the plpgsql one, which was still work in 
>> progress.  But I have progressed on this now and also converted the 
>> parser and put the local state into yyextra.  This gets rid of all 
>> internal global state now.  The patches for this are attached.  It's a 
>> lot of churn, but otherwise pretty standard stuff.
> 
> Looks good to me.
> 
>> Along the way I noticed that the flex documentation now recommends a 
>> different way to set the yyextra type.  So I have changed the ones we 
>> already have to that newer style.  I inspected the generated C code 
>> and there wasn't any significant difference, so I'm not sure, but I 
>> figure if we're making changes in this area we might as well use the 
>> modern style.
> 
> +1. According to the flex NEWS file, this syntax was added in flex 
> 2.5.34, and we already require 2.5.35.

These have been committed.  This concludes the main body of this work.

I'll let it take a lap around the buildfarm and will follow up in a few 
days on what if anything lapwing has to say about it in terms of 
warnings and what we want to do about it.