> However, many finite-state automata regex implementations have existed for years If you read his write-up on RegEx matching, you'll see notes that Thompson w

> However, many finite-state automata regex implementations have existed for years If you read his write-up on RegEx matching, you'll see notes that Thompson wrote an implementation in the mid-60s, so he definitely doesn't claim they're new. What he does claim is that most regex libraries don't use them, even when the regex they're matching to doesn't require backtracking.