Moving to JAQ 2.0

[jsuereth]

• Update Filter to only remember strings, as we can't safely precompile with new lifetime shenanigans.
• Create new jq file to hide all details of calling JQ
• Update filter/engine to start passing serde-JSON structures by default, instead of JAQ internals.
• Create error-message generation.
• Update tests.

[lquerel]

nit: I’m not entirely sure, but you could try something like this to make the intent more explicit.

fn adjust_lifetime<'a, T: 'a>(iter: impl Iterator<Item = T>) -> impl Iterator<Item = T> + 'a {
    iter
}
 
let funs = adjust_lifetime(jaq_std::funs().chain(jaq_json::funs()));
...
  .with_funs(funs)
  .compile(modules)
  ...

[jsuereth]

unfortunately, that function doesn't work (iter may not live for lifetime of 'a). What we need is to trick the compiler to infer a narrower lifetime when seeing both 'a and 'static to return 'a, and we can only do that when they are in contravariant (or return-value) position. I haven't figured out how to do that yet, but I can look that up for future cleanup. I figure it's not important enough to block this PR.

[jsuereth]

So i think I have my arrows backwards (using contravariant to mean covariant), but otherwise (while I didn't get a chance to fully read this), the answer probably lies here: https://doc.rust-lang.org/nomicon/subtyping.html

From what I can tell the variance rules are only used to change lifetimes within rust, the trick I'm using with lambda is the only way I could think of.

[lquerel]

LGTM. Just two nit comments. Thank you, that was a significant effort to transition to this new JAQ version.

[lquerel]

nit: It's probably ok but are we still supporting the same JQ core functions and definitions?

[jsuereth]

I believe we are. I'm pulling in the jaq_std defa and json defa

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 8 lines in your changes missing coverage. Please review.

Project coverage is 74.5%. Comparing base (deca2e9) to head (a2c4925).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/weaver_forge/src/jq.rs	90.3%	6 Missing ⚠️
crates/weaver_forge/src/lib.rs	75.0%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #524     +/-   ##
=======================================
+ Coverage   74.1%   74.5%   +0.4%     
=======================================
  Files         50      51      +1     
  Lines       3946    3960     +14     
=======================================
+ Hits        2926    2954     +28     
+ Misses      1020    1006     -14     

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