Reset parser context in parenthesized expression#10994
Merged
dhruvmanila merged 2 commits intodhruv/parserfrom Apr 17, 2024
Merged
Reset parser context in parenthesized expression#10994dhruvmanila merged 2 commits intodhruv/parserfrom
dhruvmanila merged 2 commits intodhruv/parserfrom
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MichaReiser
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dhruvmanila
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## Summary This PR fixes the bug where the parser would fail to parse the following code: ```python for (x in y)[0] in z: ... ``` This is because when parsing the target of a `for` statement, the context flag for the parser is set to `FOR_TARGET` and this is used by binary expression parsing to stop the expression parsing when it sees the `in` keyword. But, in parenthesized context, this is allowed. The solution implemented in this PR is to reset the parser context when parsing a parenthesized expression and set it back to the original context later. An alternative solution would be to introduce [`ExpressionContext`](https://github.com/biomejs/biome/blob/838ccb442370e72197e625a7d0e4456e6e77e498/crates/biome_js_parser/src/syntax/expr.rs#L42-L43) but that would require a lot of updates as almost all of expression parsing function would need to be updated to take this context. A benefit of this would be that both `AllowStarredExpression` and `AllowNamedExpression` can be merged in the context and everything around `ParserCtxFlags` can be removed. It could possibly also simplify certain parsing functions. ## Test Plan Add test cases and verified the snapshots.
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Summary
This PR fixes the bug where the parser would fail to parse the following code:
This is because when parsing the target of a
forstatement, the context flag for the parser is set toFOR_TARGETand this is used by binary expression parsing to stop the expression parsing when it sees theinkeyword. But, in parenthesized context, this is allowed.The solution implemented in this PR is to reset the parser context when parsing a parenthesized expression and set it back to the original context later.
An alternative solution would be to introduce
ExpressionContextbut that would require a lot of updates as almost all of expression parsing function would need to be updated to take this context. A benefit of this would be that bothAllowStarredExpressionandAllowNamedExpressioncan be merged in the context and everything aroundParserCtxFlagscan be removed. It could possibly also simplify certain parsing functions.Test Plan
Add test cases and verified the snapshots.