The AST generator creates a reference enum for each syntax group — an
enum where each variant contains a reference to the relevant syntax
node. Previously you could customize the name of the reference enum for
a group — primarily because there was an existing `ExpressionRef` type
that wouldn't have lined up with the auto-derived name `ExprRef`. This
follow-up PR is a simple search/replace to switch over to the
auto-derived name, so that we can remove this customization point.
This is a minor cleanup to the AST generation script to make a clearer
separation between nodes that do appear in a group enum, and those that
don't. There are some types and methods that we create for every syntax
node, and others that refer to the group that the syntax node belongs
to, and which therefore don't make sense for ungrouped nodes. This new
separation makes it clearer which category each definition is in, since
you're either inside of a `for group in ast.groups` loop, or a `for node
in ast.all_nodes` loop.
While looking into potential AST optimizations, I noticed the `AstNode`
trait and `AnyNode` type aren't used anywhere in Ruff or Red Knot. It
looks like they might be historical artifacts of previous ways of
consuming AST nodes?
- `AstNode::cast`, `AstNode::cast_ref`, and `AstNode::can_cast` are not
used anywhere.
- Since `cast_ref` isn't needed anymore, the `Ref` associated type isn't
either.
This is a pure refactoring, with no intended behavior changes.
This PR replaces most of the hard-coded AST definitions with a
generation script, similar to what happens in `rust_python_formatter`.
I've replaced every "rote" definition that I could find, where the
content is entirely boilerplate and only depends on what syntax nodes
there are and which groups they belong to.
This is a pretty massive diff, but it's entirely a refactoring. It
should make absolutely no changes to the API or implementation. In
particular, this required adding some configuration knobs that let us
override default auto-generated names where they don't line up with
types that we created previously by hand.
## Test plan
There should be no changes outside of the `rust_python_ast` crate, which
verifies that there were no API changes as a result of the
auto-generation. Aggressive `cargo clippy` and `uvx pre-commit` runs
after each commit in the branch.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
