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Author SHA1 Message Date
Dhruv Manilawala
7eba967e16
Refactor binary expression parsing (#11073)
## Summary

This PR refactors the binary expression parsing in a way to make it
readable and easy to understand. It draws inspiration from the suggested
edits in the linked messages in #10752.

### Changes

* Ability to get the precedence of an operator
	* From a boolean operator (`BinOp`) to `OperatorPrecedence`
	* From a binary operator (`Operator`) to `OperatorPrecedence`
	* No comparison operator because all of them have the same precedence
* Implement methods on `TokenKind` to convert it to an appropriate
operator enum
	* Add `as_boolean_operator` which returns an `Option<BoolOp>`
	* Add `as_binary_operator` which returns an `Option<Operator>`
* No `as_comparison_operator` because it requires lookahead and I'm not
sure if `token.as_comparison_operator(peek)` is a good way to implement
it
* Introduce `BinaryLikeOperator`
	* Constructed from two tokens using the methods from the second point
* Add `precedence` method using the conversion methods mentioned in the
first point
* Make most of the functions in `TokenKind` private to the module
* Use `self` instead of `&self` for `TokenKind` 

fixes: #11072

## Test Plan

Refer #11088
2024-04-23 04:42:40 +00:00
Dhruv Manilawala
13ffb5bc19
Replace LALRPOP parser with hand-written parser (#10036)
(Supersedes #9152, authored by @LaBatata101)

## Summary

This PR replaces the current parser generated from LALRPOP to a
hand-written recursive descent parser.

It also updates the grammar for [PEP
646](https://peps.python.org/pep-0646/) so that the parser outputs the
correct AST. For example, in `data[*x]`, the index expression is now a
tuple with a single starred expression instead of just a starred
expression.

Beyond the performance improvements, the parser is also error resilient
and can provide better error messages. The behavior as seen by any
downstream tools isn't changed. That is, the linter and formatter can
still assume that the parser will _stop_ at the first syntax error. This
will be updated in the following months.

For more details about the change here, refer to the PR corresponding to
the individual commits and the release blog post.

## Test Plan

Write _lots_ and _lots_ of tests for both valid and invalid syntax and
verify the output.

## Acknowledgements

- @MichaReiser for reviewing 100+ parser PRs and continuously providing
guidance throughout the project
- @LaBatata101 for initiating the transition to a hand-written parser in
#9152
- @addisoncrump for implementing the fuzzer which helped
[catch](https://github.com/astral-sh/ruff/pull/10903)
[a](https://github.com/astral-sh/ruff/pull/10910)
[lot](https://github.com/astral-sh/ruff/pull/10966)
[of](https://github.com/astral-sh/ruff/pull/10896)
[bugs](https://github.com/astral-sh/ruff/pull/10877)

---------

Co-authored-by: Victor Hugo Gomes <labatata101@linuxmail.org>
Co-authored-by: Micha Reiser <micha@reiser.io>
2024-04-18 17:57:39 +05:30