introduce hasKnownResult to optimize several parsers.#348
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@@ Coverage Diff @@
## main #348 +/- ##
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+ Coverage 96.56% 96.91% +0.34%
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Files 9 9
Lines 1049 1103 +54
Branches 94 98 +4
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+ Hits 1013 1069 +56
+ Misses 36 34 -2
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regadas
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Jan 11, 2022
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It will be interesting to see new benchmark numbers.
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@johnynek could you rebase this? |
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Yes! I will do. Thanks for the review. Note, this optimization will mostly apply to flatMap, and most parser don't need flatMap (e.g. our json benchmarks don't use flatMap). But still, I thought it was worth trying to limit the worst case. |
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@regadas let me know if this looks good. |
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Often, we can statically see what the result value will be if a parser succeeds.
If we know this, can optimize map, select and flatMap.
In particular, we can avoid reallocating a parser inside each flatMap.
Most users should avoid using flatMap anyway, but in a library function, you might need flatMap but want to get the optimization when the user passes you a constant parser.