refactor(parser): remove lookahead usage in parsing arrow function expressions

[camchenry]

• towards parser: use checkpoints instead of token lookahead #11194

Replaces all usage of the lexer lookahead functions like nth_kind, so that we only use checkpoints and rewinding, which is aligned with the TypeScript compiler implementation. This also will allow us to remove the lookahead field from the lexer in the future.

[camchenry]

• refactor(parser): remove lookahead usage in parsing arrow function expressions #11220 👈 (View in Graphite)
• refactor(parser): use checkpoints instead of peek_at in is_un_parenthesized_async_arrow_function_worker #11218
• main

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #11220 will degrade performances by 13.46%

_{Comparing 05-21-refactor_parser_remove_lookahead_usage_in_parsing_arrow_function_expressions (def05bc) with 05-20-refactor_parser_use_checkpoints_instead_of_peek_at_in_is_un_parenthesized_async_arrow_function_worker_ (a9dbf0a)}

Summary

❌ 1 regressions
✅ 37 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	mangler[cal.com.tsx]	3 ms	3.5 ms	-13.46%

[camchenry]

@Boshen is this sort of snapshot update expected? It looks like the parser error message has changed here, where before we just had "unexpected token" and now it says we were looking for a "=>", which feels better? But I'm not sure if it's correct or not, since I'm less familiar with the parser changes.

[camchenry]

Actually, it looks like this is correct I think. This is the same error that TypeScript will emit:

https://www.typescriptlang.org/play/?#code/BQOjEMEoAIGpoIwCgg

[Boshen]

@Boshen is this sort of snapshot update expected? It looks like the parser error message has changed here, where before we just had "unexpected token" and now it says we were looking for a "=>", which feels better? But I'm not sure if it's correct or not, since I'm less familiar with the parser changes.

Yes! We expect more alignment to tsc from making these changes.

[Boshen]

Merge activity

• May 22, 2:58 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• May 22, 2:58 AM UTC: Boshen added this pull request to the Graphite merge queue.
• May 22, 3:06 AM UTC: Merged by the Graphite merge queue.