Left-value parsing cleanup #17160
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Left-value parsing cleanup #17160
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The current logic is taken from the flow plugin
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JLHwung
commented
Mar 3, 2025
| "throws": "Unexpected token (1:7)" | ||
| } |
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The input is async(x?), previously we threw on ) now we throw on ?.
| // These tokens cannot start an expression, so if one of them follows | ||
| // ? then we are probably in an arrow function parameters list and we | ||
| // don't parse the conditional expression. | ||
| if ( |
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Nice, did you check how this improves perf?
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Just added a benchmark case, here is the result on my machine:
baseline 256 nested conditional expressions with typescript: 7_828 ops/sec ±0.4% (0.128ms)
baseline 512 nested conditional expressions with typescript: 3_740 ops/sec ±0.2% (0.267ms)
baseline 1024 nested conditional expressions with typescript: 1_875 ops/sec ±0.16% (0.533ms)
baseline 2048 nested conditional expressions with typescript: 0 ops/sec ±0% (0ms)
current 256 nested conditional expressions with typescript: 8_108 ops/sec ±0.42% (0.123ms)
current 512 nested conditional expressions with typescript: 4_036 ops/sec ±0.29% (0.248ms)
current 1024 nested conditional expressions with typescript: 1_977 ops/sec ±0.23% (0.506ms)
current 2048 nested conditional expressions with typescript: 947 ops/sec ±0.45% (1.056ms)
It is 8% faster than the baseline. It turns out the baseline can't handle 2048 nested conditional expressions within parentheses, probably it hits certain memory limit, while the new approach works well.
nicolo-ribaudo
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Mar 3, 2025
liuxingbaoyu
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Mar 3, 2025
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nicolo-ribaudo
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Mar 3, 2025
laine-hallot
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to laine-hallot/uwu-parser
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Mar 31, 2025
* cleanup * refactor: simplify checkProto implementation * rename test * refactor: avoid second scan in type cast transform * refactor: simplify ts parseConditional The current logic is taken from the flow plugin * add benchmark cases
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Further clean up the left-value parsing. This PR can be reviewed by commits.