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(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> |
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| CONTRIBUTING.md | ||
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| README.md | ||
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Ruff Formatter
The Ruff formatter is an extremely fast Python code formatter that ships as part of the ruff
CLI.
Goals
The formatter is designed to be a drop-in replacement for Black, but with an excessive focus on performance and direct integration with Ruff.
Specifically, the formatter is intended to emit near-identical output when run over Black-formatted code. When run over extensive Black-formatted projects like Django and Zulip, > 99.9% of lines are formatted identically. When migrating an existing project from Black to Ruff, you should expect to see a few differences on the margins, but the vast majority of your code should be unchanged.
If you identify deviations in your project, spot-check them against the intentional deviations enumerated below, as well as the unintentional deviations filed in the issue tracker. If you've identified a new deviation, please file an issue.
When run over non-Black-formatted code, the formatter makes some different decisions than Black, and so more deviations should be expected, especially around the treatment of end-of-line comments. For details, see Black compatibility.
Getting started
The Ruff formatter is available as of Ruff v0.1.2. Head to The Ruff Formatter for usage instructions and a comparison to Black.