ruff/crates/ruff_python_formatter
Ibraheem Ahmed c9dff5c7d5
[ty] AST garbage collection (#18482)
## Summary

Garbage collect ASTs once we are done checking a given file. Queries
with a cross-file dependency on the AST will reparse the file on demand.
This reduces ty's peak memory usage by ~20-30%.

The primary change of this PR is adding a `node_index` field to every
AST node, that is assigned by the parser. `ParsedModule` can use this to
create a flat index of AST nodes any time the file is parsed (or
reparsed). This allows `AstNodeRef` to simply index into the current
instance of the `ParsedModule`, instead of storing a pointer directly.

The indices are somewhat hackily (using an atomic integer) assigned by
the `parsed_module` query instead of by the parser directly. Assigning
the indices in source-order in the (recursive) parser turns out to be
difficult, and collecting the nodes during semantic indexing is
impossible as `SemanticIndex` does not hold onto a specific
`ParsedModuleRef`, which the pointers in the flat AST are tied to. This
means that we have to do an extra AST traversal to assign and collect
the nodes into a flat index, but the small performance impact (~3% on
cold runs) seems worth it for the memory savings.

Part of https://github.com/astral-sh/ty/issues/214.
2025-06-13 08:40:11 -04:00
..
resources/test/fixtures Treat ty: comments as pragma comments (#18532) 2025-06-07 16:02:43 +02:00
src [ty] AST garbage collection (#18482) 2025-06-13 08:40:11 -04:00
tests [ty] AST garbage collection (#18482) 2025-06-13 08:40:11 -04:00
Cargo.toml [red-knot] Add 'Format document' to playground (#17217) 2025-04-07 09:26:03 +02:00
CONTRIBUTING.md [ty] AST garbage collection (#18482) 2025-06-13 08:40:11 -04:00
generate.py Implement template strings (#17851) 2025-05-30 15:00:56 -05:00
orphan_rules_in_the_formatter.svg Generate FormatRule definitions (#4724) 2023-06-01 08:38:53 +02:00
README.md Add f-string formatting to the docs (#15367) 2025-01-09 10:20:06 +01:00

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 Style Guide.

Getting started

Head to The Ruff Formatter for usage instructions and a comparison to Black.