Kevin Newton | A Ruby Regular Expression EngineJan 06, 2026 Recently I put some finishing touches on the exreg gem, a pure-Ruby implementation of a Unicode regular expression engine. It supports nearly all of the same functionality as Onigmo, the Ruby regular expression engine, with caveats listed in the README. Importantly however, it uses a Thompson-style NFA virtual machine, meaning it is immune to ReDoS caused by catastrophic backtracking.
