BUburntsushi·Apr 27, 2014
Yeah, this is really the only comparison I have so far. It was included with a PR for adding regexes to Rust, so hopefully it will make it into the shootout proper in the next release.
I also have some more specific benchmarks against Go: https://github.com/BurntSushi/regexp/tree/master/benchmark
(For any curious readers out there, the benchmark is multithreaded in Rust[1], with a particularly nice use of futures.)
> Rust beats Go pretty soundly (on this specific benchmark), but C beats Rust pretty soundly.
I believe the dynamic regexes also beat Go on this specific benchmark, but the optimizing compiler is likely to blame there. (And to be clear, Go still beats Rust native regexes in some benchmarks, primarily because it has more clever optimizations. It was written by Russ Cox, after all!)
> Why is C so much faster?
The C program is pre
Read the rest
tty elaborate, but here are my guesses.
* There are many ways to implement regex matching. For example, RE/C++ uses both a very very quick DFA and a NFA simulation. My library only has the (slower) NFA simulation. I don't know what Tcl uses for an implementation strategy, but whatever it is, it's likely a factor.
* If string replacement is done in place, then it's going to avoid a good chunk of allocation. (In this particular benchmark, it would be perfectly legal to do string replacement in place.)
I'm sure there are other things I'm missing, but these seem like good candidates for a good chunk of the difference.
[1] - https://github.com/BurntSushi/regexp/blob/master/benchmark/r...