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## 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. |
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Ruff Python Parser
Ruff's Python parser is a hand-written recursive descent parser which can parse Python source code into an Abstract Syntax Tree (AST). It also utilizes the Pratt parsing technique to parse expressions with different precedence.
Try out the parser in the playground.
Python version support
The parser supports the latest Python syntax, which is currently Python 3.12.
It does not throw syntax errors if it encounters a syntax feature that is not
supported by the target-version.
This will be fixed in a future release (see https://github.com/astral-sh/ruff/issues/6591).
Contributing
Refer to the contributing guidelines to get started and GitHub issues with the parser label for issues that need help.