Re: [review][JSON] Some thoughts on recent reviews

From: Tom Honermann (tom_at_[hidden])
Date: 2020-09-23 22:21:32

On 9/23/20 3:07 PM, Peter Dimov via Boost wrote:
> Niall Douglas wrote:
>> Hana's runtime benchmarks showed her regex implementation far 
>> outpacing any of those in the standard libraries. Like, an order of 
>> magnitude in absolute terms, linear scaling to load instead of 
>> exponential for common regex patterns. A whole new world of performance.
>>
>> Part of why her approach is so fast is because she didn't implement 
>> all of regex. But another part is because she encodes the parse into 
>> relationships between literal types which the compiler can far more 
>> aggressively optimise than complex types. So basically the codegen is 
>> way better, because the compiler can eliminate a lot more code.
>
> I've looked at CTRE, I know what it does, how it does it, and how well 
> it performs. It is, as I said, a remarkable piece of engineering, and 
> I respect Hana for her work. 
> https://pdimov.github.io/blog/2020/05/15/its-a-small-world/
>
> Nevertheless, I have a not-entirely-uninformed hunch that a runtime 
> engine can perform on par. Of course, until/unless I can substantiate 
> this more thoroughly, by for example writing a runtime regex engine 
> that exhibits similar performance to CTRE, you can file this under 
> "idle speculation".

Please let me know when/if evidence becomes available that elevates this 
beyond "idle speculation".

Tom.