This massive PR implements an alternative Python parser that will allow LibCST to parse Python 3.10's new grammar features. The parser is implemented in Rust, but it's turned off by default through the `LIBCST_PARSER_TYPE` environment variable. Set it to `native` to enable. The PR also enables new CI steps that test just the Rust parser, as well as steps that produce binary wheels for a variety of CPython versions and platforms.
Note: this PR aims to be roughly feature-equivalent to the main branch, so it doesn't include new 3.10 syntax features. That will be addressed as a follow-up PR.
The new parser is implemented in the `native/` directory, and is organized into two rust crates: `libcst_derive` contains some macros to facilitate various features of CST nodes, and `libcst` contains the `parser` itself (including the Python grammar), a `tokenizer` implementation by @bgw, and a very basic representation of CST `nodes`. Parsing is done by
1. **tokenizing** the input utf-8 string (bytes are not supported at the Rust layer, they are converted to utf-8 strings by the python wrapper)
2. running the **PEG parser** on the tokenized input, which also captures certain anchor tokens in the resulting syntax tree
3. using the anchor tokens to **inflate** the syntax tree into a proper CST
Co-authored-by: Benjamin Woodruff <github@benjam.info>
which ensures we won't have inconsistent black-vs-isort errors
going forward. We can always format by running `ufmt format .`
at the root, and check with `ufmt check .` in our CI actions.
## Summary
The pyre stub for the tokenizer module had a syntax error.
Fixing it removes other pyre errors.
## Test Plan
```
pyre check
```
Co-authored-by: Germán Méndez Bravo <kronuz@fb.com>
We've forked parso internally, so we no longer need a dependency on it. This
exposed an unused version info function that still referenced parso, so I
deleted it.
This ports `CSTNode.validate_types_shallow` and
`CSTNode.validate_types_deep`, as well as `libcst._type_enforce` to the
open-source release.
These are useful if someone wants to use LibCST without a static type
checker.
These weren't originally included because `libcst._type_enforce` wasn't
3.7 compatible.
