refactor(parser): rewrite arrow function parsing to remove rewind in hot paths

[camchenry]

This is a major work-in-progress. May not even be merged.

[camchenry]

• refactor(parser): rewrite arrow function parsing to remove rewind in hot paths #11483 👈 (View in Graphite)
• main

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[Boshen]

Best chance is to avoid rewind on hot path such as () => {}, x => {}, (x) => {} etc

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #11483 will degrade performances by 11.31%

_{Comparing 06-04-refactor_parser_rewrite_arrow_function_parsing_to_be_lookahead-free (08d8634) with main (bfa05f2)}

Summary

❌ 3 regressions
✅ 35 untouched benchmarks

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

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	mangler[cal.com.tsx]	2.7 ms	3.1 ms	-11.31%
❌	parser[binder.ts]	3.4 ms	3.6 ms	-5.42%
❌	parser[react.development.js]	1.4 ms	1.4 ms	-5.79%

[camchenry]

Okay, I've gotten this to a working state now. I need to verify that the hot paths don't rewind though. As evidenced above, just focus on arrow function parsing can have a huge effect since it's a commonly used feature. We are also rewinding in like 90% of the other cases, and only not rewinding on things like () => {} or () => expr.

[camchenry]

Going to close this out as I don't have capacity right now to continue with this approach.