real-regex

Linear-time, ReDoS-safe regular expressions with bounded lookarounds — Rust bindings to the REAL C++ engine.

Every pattern that compiles matches in time linear in the input. There is no backtracking, so no catastrophic blow-up: the pathological (a+)+b that hangs a backtracking engine runs in microseconds here. The engine is strict by design — a construct it cannot run linearly (a backreference, an unbounded lookaround) is rejected at compile time, never silently made non-linear.

use real_regex::Regex;

let re = Regex::new(r"(\w+)@(\w+)").unwrap();
for m in re.find_iter("a@b cd@ef") {
    println!("{:?} / {:?}", m.get(1), m.get(2));
}

Unlike RE2 and the regex crate, REAL supports bounded lookahead and lookbehind — in linear time. The engine and this crate share one calendar version.

License

MIT.