Add session context to evaluation

[jpschorr]

Fixes #388

Adds both a system-level and a user-level session context to the evaluation context. Also plumbs the context through to BaseTableExpr used in partiql_catalog::Extensions.

There is a lot of fiddly lifetime management and testing changes, as well as some slight trait refactors.

It's probably easiest to start with

• the new integration test in partiql/tests/user_context.rs to see what kinds of things are possible,
• partiql-catalog/src/context.rs for the new context traits, and
• partiql-eval/src/eval/mod.rs for how it's used in evaluation.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Attention: Patch coverage is 87.28522% with 37 lines in your changes are missing coverage. Please review.

Project coverage is 79.21%. Comparing base (00924f2) to head (0a8d71b).

Files	Patch %	Lines
partiql-eval/src/eval/mod.rs	59.37%	12 Missing and 1 partial ⚠️
partiql-eval/src/error.rs	0.00%	9 Missing ⚠️
partiql-eval/src/eval/expr/operators.rs	57.14%	6 Missing ⚠️
partiql-eval/src/eval/expr/strings.rs	0.00%	6 Missing ⚠️
partiql-catalog/src/context.rs	75.00%	1 Missing ⚠️
partiql-eval/src/eval/evaluable.rs	97.36%	1 Missing ⚠️
partiql-logical-planner/src/lower.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #446      +/-   ##
==========================================
+ Coverage   79.10%   79.21%   +0.11%     
==========================================
  Files          65       66       +1     
  Lines       17517    17721     +204     
  Branches    17517    17721     +204     
==========================================
+ Hits        13856    14037     +181     
- Misses       3091     3116      +25     
+ Partials      570      568       -2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

Conformance comparison report

	Base (00924f2)	553d22f	+/-
% Passing	90.35%	90.35%	0.00%
✅ Passing	5731	5731	0
❌ Failing	612	612	0
🔶 Ignored	0	0	0
Total Tests	6343	6343	0

Number passing in both: 5731

Number failing in both: 612

Number passing in Base (00924f2) but now fail: 0

Number failing in Base (00924f2) but now pass: 0

[sadderchris]

Is there any way this API can output a generic C instead of a Option<&dyn Any>? I'd really like to implement these traits myself and just return a type that I choose, instead of going through a Option<&dyn Any>.

[jpschorr]

If there is, I don't see how.

Making it a generic parameter of the SessionContext would mean that any and all extensions that are loaded would need to be able to deal with that single type.

[sadderchris]

We'll probably define our own context type, but for the most flexibility, this should be &'a (dyn Any + 'a) to support types that contain lifetimes themselves (e.g. &'a Foo<'a> - else you can only store something that is &'a Foo<'static>).

...This doesn't seem to just work however. I think the user_context method on the SessionContext trait needs to be updated as well

fn user_context<'b>(&'b self, name: &str) -> Option<&'b (dyn Any + 'b)> {}

There might be some other hoops that need to be jumped through as well.

[jpschorr]

Any is defined as

pub trait Any: 'static {...}

(See https://doc.rust-lang.org/std/any/trait.Any.html)

So you can't add a + 'a

[sadderchris]

Ok, this won't work for us then. Do you have some time to talk about this in person tomorrow?

I think I've worked out a way around this problem actually - let's still sync up tomorrow if possible.

[am357]

Approved with one suggestion