fancy-regex VS pomsky

https://github.com/fancy-regex/fancy-regex/issues/84 it's still open issue

Ahh, very interesting, thanks for sharing! Do you have any thoughts around why that is? I presume that's due to Oniguruma supporting a much broader feature set and something like fancy-regexp's approach with mixing a backtracking VM and NFA implementation for simple queries would be needed for better perf? (I am aware you played a role in that) [1]

I have been playing around with regex parsing through building parsers through parser combinators at runtime recently, no clue how it will perform in practice yet (structuring parser generators at runtime is challenging in general in low-level languages) but maybe that could pan out and lead to an interesting way to support broader sets of regex syntaxes like POSIX in a relatively straightforward and performant way.

[1] https://github.com/fancy-regex/fancy-regex#theory

Not an expert but fancy regex is a Rust library that uses a hybrid approach to detect whether a sub expression contains backtracking and delegates to the appropriate engine.

https://github.com/fancy-regex/fancy-regex

I started with JS, and my first step was to write a simple script that checks if a regex is valid. I can call this script from Rust, but there's a problem: Starting a nodejs process takes about 100ms, which is not acceptable, especially for fuzzing.

I noticed this when a test case of a parser I wrote failed in CI on Windows. I then learned that the default stack size on Windows is only 1 MiB whereas its 8 MiB on Linux if I remember correctly. The parser has a hard-coded recursion limit to prevent stack overflows, which is currently set to 128. However, this limit is lower than necessary on Linux, and might still be too high for some platforms (embedded?)

I was informed that Rulex is a registered trademark and I'm not allowed to use the name for my project. A lawyer contacted me and gave me a week to rename the project, so I have to come up with a different name :(

In the other discussion, there's also a link to Rulex, which has similar goals but is more concise. Also claims to compile to multiple regex dialects.

Something similar happened to me a week ago. Someone emailed me that they found panics in rulex, and then created a PR to fix them. They even explained to me how to create a security advisory on GitHub because the panics could be used to DoS someone. It was very helpful.

Sorry for not being more specific. Since this is a parser, the span points into the text file that is being parsed, so it's not that relevant for most libraries. Here is the parser, it uses nom parser combinators. Unfortunately, and adding the spans to the errors involves some boilerplate.

I welcome contributions for rulex. It's a medium-sized project that should be fairly easy to understand, and has some "good first issues" :)

Rulex – A new, portable, regular expression language\ (102 comments)