regex-benchmark VS regex

Before we start comparing the aforementioned solutions, it is worth to show how bad things are with the standard regex library in Go. I found the project where the author compares the performance of standard regex engines of various languages. The point of this benchmark is to repeatedly run 3 regular expressions over a predefined text. Go came in 3rd place in this benchmark! From the end....

* Let you clone a map without rehashing every key to a new seed. I generally measure at least 15x speedup from this alone, unlocking very useful design patterns like "clone a map and apply a few temporary updates for a one-off operation like validation or simulation" with no extra code complexity. Go gives you no better option than slowly rehashing the entire map.

And that's just hash maps. How about Go's regex engine being one of the slowest in the world while Rust's regex crate being one of the fastest:

https://github.com/mariomka/regex-benchmark#optimized

Languages Regex Benchmark

Java is still pretty bad compared to C# (not to mention Rust or Nim)

https://github.com/mariomka/regex-benchmark

And the always interesting techempower Project, which leaves the implementation to participants of each round. https://www.techempower.com/benchmarks/#section=data-r21&tes...

Choose whatever category you wish there, js is faster in then go in almost all categories there.

Even though I said it before, I'm going to repeat myself as I expect you to ignore my previous message: the language doesn't make any implementation fast or slow. You can have a well performing search engine in go, and JS. The performance difference will most likely not be caused by the language with these two choices. And the same will apply with C/Rust. The language won't make the engine performant creating a maximally performant search engine is hard

Also, regex engines are not created equally, at all. One of the best writeups I've ever read is from the ripgrep blog. Burntsushi knows regex. There's also this benchmark site which illustrates how general language performance is an entirely different metric than regex performance. Don't assume those benchmarks will cover your particular use case, though--different regex engines might handle your particular situation differently.

Interesting. Looking at this repo, they have

Rust -> Ruby -> Java -> Golang

https://github.com/mariomka/regex-benchmark

Though it appears the numbers are two years old or so, and only for 3 specific regexes.

id also be careful in claiming C++ std regex is faster than python, unless you actually have proof. there's a ton of information that in many cases its actually slower. https://github.com/mariomka/regex-benchmark. have you actually benchmarked your code? or was it just a naive assumption that because its C++ its just fast?

It is a matter of personal preference.

I find that regular expressions and text-wrangling tasks are faster and easier in Perl than in other programming languages due to its accessible syntax and regular expression engine speed.

This article shows the regular expression syntax in several popular programming languages: https://cs.lmu.edu/~ray/notes/regex/

This GitHub repo gives some regex performance test benchmarks: https://github.com/mariomka/regex-benchmark Perl is pretty fast among the scripting languages that were benchmarked.

If you are familiar with C / C++, then learning Perl is relatively fast and easy: https://perldoc.perl.org/perlintro

The homepage has a benchmark that compares Zed's "insertion latency" to other editors, and this is the description:

> Open input.rs at the end of line 21 in rust-lang/regex. Type z 10 times, measure how long it takes for each z to display since hitting the z key.

Could someone clarify what that means? My interpretation of that was to go to https://github.com/rust-lang/regex/blob/master/regex-cli/arg... and start typing 'z' at the end of line 21, but that doesn't seem to make any sense. I guess that repo got refactored and those instructions are out of date?

We also used the avenue to sluggify the question title. We used regex to fish out and replace all occurrences of punctuation and symbol characters with an empty string and using the itertools crate, we joined the words back together into a single string, where each word is separated by a hyphen ("-").

Command-Line Rust taught me how to use crates like clap, assert_cmd, and regex. I felt lost before because I didn't know about Rust's ecosystem--which is arguably as important as the language itself. Also, looking up and comparing libraries is a tiring task! blessed.rs is nice but Command-Line Rust really saved me from analysis paralysis.

burntsushi actually regrets making regex replace return a Cow: https://github.com/rust-lang/regex/issues/676#issuecomment-6.... I’m glad it does, and wish it took an impl Into> there, for the reasons discussed in the issue, but burntsushi has a lot more experience of the practical outcomes of this. Just something more to think about.

I'm not familiar with the AoC problem. You might be able to. But RegexSet doesn't give you match offsets.

You can drop down to regex-automata, which does let you do multi-regex search and it will tell you which patterns match[1]. The docs have an example of a simple lexer[2]. But... that will only give you non-overlapping matches.

You can drop down to an even lower level of abstraction and get multi-pattern overlapping matches[3], but it's awkward. The comment there explains that I had initially tried to provide a higher level API for it, but was unsure of what the semantics should be. Getting the starting position in particular is a bit of a wrinkle.

[1]: https://docs.rs/regex-automata/latest/regex_automata/meta/in...

[2]: https://docs.rs/regex-automata/latest/regex_automata/meta/st...

[3]: https://github.com/rust-lang/regex/blob/837fd85e79fac2a4ea64...

It’s not quite that simple, but folks are working on it.

https://github.com/rust-lang/regex/issues/425#issuecomment-1...

https://github.com/helix-editor/helix/pull/211#issuecomment-...

Dependencies used: - regex - unicode_reader - rust decimal - tokio

https://www.cs.princeton.edu/courses/archive/fall19/cos226/l... and https://kean.blog/post/lets-build-regex are excellent introductions to implementing a (very) simplified regex engine: construct a nondetermistic finite state automaton for the regex, then perform a graph search on the resulting digraph; if the vertex corresponding to your end state is reachable, you have a match.

I think this exercise is valuable for anyone writing regexes to not only understand that there's less magic than one might think, but also to visualize a bunch of balls bouncing along an NFA - that bug you inevitably hit in production due to catastrophic backtracking now takes on a physical meaning!

Separately re: the OP, https://github.com/rust-lang/regex/issues/822 (and specifically BurntSushi's comment at the very end of the issue) adds really useful context to the paragraph in the OP about niche APIs: https://blog.burntsushi.net/regex-internals/#problem-request... - searching with multiple regexes simultaneously against a text is both incredibly complex and incredibly useful, and I can't wait to see what the community comes up with for this pattern!