Add an AST visitor

[benesch]

Resubmission of #78, which caused some compilation failures due to merge skew when it landed. @andygrove are you game to try this again?

[coveralls]

Pull Request Test Coverage Report for Build 387

• 675 of 728 (92.72%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.08%) to 92.322%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/ast/visit.rs	675	728	92.72%

Totals
Change from base Build 386:	0.08%
Covered Lines:	5002
Relevant Lines:	5418

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💛 - Coveralls

[malobre]

An AST visitor would be a nice thing to have.
@andygrove Could you consider merging this PR ?

[wseaton]

Bumping this, adding an AST visitor would make it much easier to use sqlparser-rs to extract particular metadata from queries like "what tables are referenced in this query".

@benesch I see you did some work on MaterializeInc/materialize#3288 in auto-generating the visitor, is this something that could potentially be upstreamed, maybe have walkabout run on pre-commit hook to force the vistior to be regenerated?

[benesch]

Maybe! The build script approach, rather than the manual regeneration approach, has been working well for us though. We could consider open sourcing the walkabout crate on which the visitor generation depends, but I don’t know that anyone at Materialize has much time to work on this at the moment. There’s an old PR from me on this repo somewhere that has a manual implementation of the visitor, which might be of interest.

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On Tue, Mar 30, 2021 at 1:16 PM Will Eaton ***@***.***> wrote: Bumping this, adding an AST visitor would make it much easier to use sqlparser-rs to extract particular metadata from queries like "what tables are referenced in this query". @benesch <https://github.com/benesch> I see you did some work on MaterializeInc/materialize#3288 <MaterializeInc/materialize#3288> in auto-generating the visitor, is this something that could potentially be upstreamed, maybe have walkabout run on pre-commit hook to force the vistior to be regenerated? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#114 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAGXSICWCA5MZAPQH3LPGJ3TGIBPZANCNFSM4HW6JRQQ> .

[alamb]

Hi @benesch -- sorry for the delay in review. I am going to help out now with this repo and we are working to clear the backlog. Is this PR still something you would like to work on to help contribute?

[alamb]

Closing due to staleness -- feel free to reopen this PR or create a new one if you plan to keep working on this