Kleingrep

Kleingrep is a regular expression engine, providing a library and command-line tool written in Go.

It aims to provide a more featureful engine, compared to the one in Go's regexp, while retaining some semblance of efficiency.

The engine does not use backtracking, relying on the NFA-based method described in Russ Cox's articles. As such, it is immune to catastrophic backtracking.

It also includes features not present in regexp, such as lookarounds and backreferences.

Syntax

The syntax is, for the most part, a superset of Go's regexp. A full overview of the syntax can be found here.

For more information, see https://pkg.go.dev/gitea.twomorecents.org/Rockingcool/kleingrep/regex.

How it works

I've written about the inner workings of the engine on my blog.