dk.brics.automaton - finite-state automata and regular expressions for Java

This Java package contains a DFA/NFA (finite-state automata) implementation with Unicode alphabet (UTF16) and support for the standard regular expression operations (concatenation, union, Kleene star) and a number of non-standard ones (intersection, complement, etc.)

In contrast to many other automaton/regexp packages, this package is fast, compact, and implements real, unrestricted regular operations. It uses a symbolic representation based on intervals of Unicode characters.

The full source code and documentation is available under the BSD license.

View the online javadoc API specifications. The central classes are Automaton and RegExp.
Download the precompiled Java archive or get it from Maven Central Repository.
See the Java source code.
Looking for ports to other languages? See David Lutterkort's libfa library for C and Nikos Baxevanis's Fare library for .NET/C#.
Got questions? See the FAQ.

The latest version 1.12-4 was released January 3, 2022. (ChangeLog)

The dk.brics.automaton package is developed by Anders Møller at Aarhus University, with contributions, suggestions and bug reports from Alexandar Bakic, Jodi Moran, Brandon Lee, David Lutterkort, John Gibson, Alex Meyer, Daniel Lowe, Harald Zauner, Dawid Weiss, Robert Muir, Hans-Martin Adorf, Dale Richardson, Yannick Versley, Gustaf Lundh, Victor Berchet, Astrid Muriel Waindja Younang, Valentin Wüstholz, Simon Gregersen, and Lewis John McGibbney.