Extend incremental reparsing to all braced blocks

[matklad]

The incremental reparsing model of libsyntax2 is curly-block based.

• in the parser, we make sure that, for any pair of { and }, there's a syntax node for which curlys are the first and the last child.
• this gives us corollary: if edit is inside a matching pair of braces, and the pair remains matching after the edit is applied, the effects of the edit are contained to a single block.
• this gives a rise to incremental re parsing algorithm: find closest curly-block, verify its structure, reparse.

Currently only expr blocks and struct blocks participate in this algorithm, but it should be extended to any kind of braced block. Here's the relevant code:

https://github.com/matklad/libsyntax2/blob/4f647096665b2ca3725ba1f7415a21fbc46044bb/crates/libsyntax2/src/lib.rs#L145-L147

it should be extended to all braced blocks. The relevant tests are here:

https://github.com/matklad/libsyntax2/blob/4f647096665b2ca3725ba1f7415a21fbc46044bb/crates/libsyntax2/tests/test/main.rs#L42

It would be nice to use proptest or fuzzing to check incremental re parsing! (cc @killercup on the last one). Here's the top-level repasing API:

https://github.com/matklad/libsyntax2/blob/4f647096665b2ca3725ba1f7415a21fbc46044bb/crates/libsyntax2/src/lib.rs#L81

[darksv]

Hi! I want to take it.

[matklad]

Cool, if there's any question I can help with, don't hesitate to ask here, @darksv ! A good first start is perhaps to just add a single more block to the list of cases, for example, a match_arm_list.

[darksv]

Thank you. I have implemented reparsing for remaining blocks. Now I want to give proptest a go and add more tests.