Add support for unevaluatedProperties + a few other changes.

[tobz]

Closes #288.

This PR adds support for unevaluatedProperties when using the draft201909 or draft202012 feature flags.

Overall approach

I took a somewhat similar approach to the Python code linked in the issue for this feature, where the validator for unevaluatedProperties uses a subvalidator for each relevant keyword -- properties, patternProperties, dependentSchemas, $ref, etc -- that performs the relevant logic for determining if the given schema for the keyword would evaluate the property.

Each subvalidator exposes an interface that looks a lot like the Validate trait, but is oriented towards checking solely if a property would be valid against the schema, and has an optional return value to indicate evaluated vs not evaluated. The validator code, overall, is a bit verbose, not unlike additionalProperties... but there's a possibility of turning the API into an actual trait which would theoretically allow us to reduce a lot of boilerplate when we check each subvalidator in UnevaluatedPropertiesValidator::is_valid_property, and so on.

Code deduplication and refactoring

Beyond that, I ended up refactoring a little bit of the shared code between unevaluatedProperties and additionalProperties. I tried, initially, to carry over the logic for switching between a small and big validator map, but it got a little too complex when considering that UnevaluatedPropertiesValidator is inherently recursive, and it didn't make a lot of sense propagating a generic validator map type all the way through. I'm happy to try and revisit this if you think it matters enough.

Fixing $ref for draft 2019-09 and newer

In order to fully support unevaluatedProperties, I had to do a small bit of refactoring in terms of how $ref is handled. This also had the nice side effect of fixing $ref usage when using draft 2019-09 and newer, as now it can be evaluated alongside other keywords.

Beyond that, there's just a lot of boilerplate, and I tried to pick a code style/pattern and just stick to that and be consistent about it, but I'm happy to do any of the aforementioned refactoring ideas, or anything else, to bring the code more in line with your expectations.

[tobz]

Seeing the CI: I'll rebase this locally in a little while to get this using a proper conventional commit message.

[Stranger6667]

Amazing job, thank you! I have one minor comment :)

[codecov]

Codecov Report

Merging #419 (a37e8ca) into master (848b7b1) will increase coverage by 0.80%.
The diff coverage is 83.68%.

@@            Coverage Diff             @@
##           master     #419      +/-   ##
==========================================
+ Coverage   78.59%   79.40%   +0.80%     
==========================================
  Files          54       56       +2     
  Lines        4481     5015     +534     
==========================================
+ Hits         3522     3982     +460     
- Misses        959     1033      +74     

Impacted Files	Coverage Δ
jsonschema/src/lib.rs	66.66% <ø> (+9.52%)	⬆️
jsonschema/src/paths.rs	75.29% <0.00%> (-1.82%)	⬇️
jsonschema/src/keywords/ref_.rs	80.88% <57.14%> (-6.40%)	⬇️
jsonschema/src/error.rs	58.28% <62.50%> (+0.56%)	⬆️
jsonschema/src/properties.rs	63.63% <63.63%> (ø)
jsonschema/src/schemas.rs	89.18% <80.00%> (-0.44%)	⬇️
jsonschema/src/keywords/unevaluated_properties.rs	87.12% <87.12%> (ø)
jsonschema/src/compilation/mod.rs	85.54% <88.88%> (+4.86%)	⬆️
jsonschema/src/keywords/additional_properties.rs	84.81% <100.00%> (+1.85%)	⬆️
jsonschema/src/validator.rs	83.33% <100.00%> (+1.51%)	⬆️

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[Stranger6667]

Great PR and a great write-up! :) Thank you so much for this!

[tobz]

@Stranger6667 🙇🏻 Happy to be able to contribute back.

Do you have a typical release cycle for jsonschema? Just doing a little planning on my end if I should keep my fork around or not.

[Stranger6667]

I don't but I'd like to make a new release today :)

[tobz]

Great, I'll keep an eye out for when that happens.

Appreciate the timeliness on the review and the release; certainly did not expect my PR to be getting this much traction so quickly. 😂

[Stranger6667]

My pleasure :) Happy to see your contribution and that's great that jsonschema is getting closer to the full Draft 2019-09 support :)

[Stranger6667]

0.17.0 is released :)