Mata: A Fast and Simple Finite Automata Library

Mata is a well-engineered automata library written in C++ that offers a unique
combination of speed and simplicity. It is meant to serve in applications such as
string constraint solving and reasoning about regular expressions, and as
a reference implementation of automata algorithms. Besides basic algorithms for
(non)deterministic automata, it implements a fast simulation reduction and
antichain-based language inclusion checking. The simplicity allows
a straightforward access to the low-level structures, making it relatively easy
to extend and modify. Besides the C++ API, the library also implements a Python
binding.
The library comes with a large benchmark of automata problems collected from
relevant applications such as string constraint solving, regular model checking,
and reasoning about regular expressions. We show that Mata is on this benchmark
significantly faster than all libraries from a wide range of automata libraries
we collected. Its usefulness in string constraint solving is demonstrated by the
string solver Z3-Noodler, which is based on Mata and outperforms the state of the
art in string constraint solving on many standard benchmarks.