Support type alias statements in simple statement positions #8916
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| /// The lexer is within brackets, with the given bracket nesting depth. | ||
| Nested(u32), | ||
| /// The lexer is some other location. | ||
| Other, |
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This and Nested could be combined, since this is just Nested with a depth of 0. Alternatively, Nested could be NonZeroU32. But both felt clunkier in practice. Open to changing, though.
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| Tok::Colon if matches!(self.position, Position::Other) => { | ||
| self.position = Position::SimpleStatement; | ||
| } |
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Nit: You could implement Eq on Position so that you can use == instead of matches
| // ```python | ||
| // class Class: type X = int | ||
| // ``` | ||
| Tok::Colon if matches!(self.position, Position::Other) => { |
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Just looking at the colon itself might not be sufficient because colons are also used to separate type annotations, slice indices, etc). I'm not sure if this is an issue here, but let's add a few more tests, e.g. a: type X = int (which should not be valid)
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In the logical line rules, we have some more extensive logic to ensure that the colon follows a statement keyword (like class). I could add that here...
| @@ -93,7 +98,10 @@ where | |||
| // 2. The type token is immediately followed by a name token. | |||
| // 3. The name token is eventually followed by an equality token. | |||
| Tok::Type => { | |||
| if self.start_of_line { | |||
| if matches!( | |||
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Unrelated to your change: It's somewhat unfortunate that it's necessary to track whether we're at the start of the line, because we already know this inside of the Lexer.
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Definitely. Perhaps we could move this into the lexer...
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Summary
Our
SoftKeywordTokenizeronly respected soft keywords in compound statement positions -- for example, at the start of a logical line:However, type aliases can also appear in simple statement positions, like:
(Note that
matchandcaseare not valid keywords in such positions.)This PR upgrades the tokenizer to track both kinds of valid positions.
Closes #8900.
Closes #8899.
Test Plan
cargo test