Doug McIlroy's C++ regular expression matching library
I still haven&#x27;t found a single regex library that can do a few tasks that I find to be very critical: (1) accept the input string in pieces (i.e., lazily), (2) let you make copies of the recognition automaton in the middle of recognition so that you can run them on different suffixes, (3) tell you what characters&#x2F;strings are valid suffixes of the current automaton. (Well, I would also like (4) lazily creates a DFA whenever the pattern allows it, and (5) works on non-string data, but I&#x27;ve given up on these since it seems to me nobody even cares about linear-time matching or non-string data.)<p>Requirements 1-3 are extremely important when you have a trie-like data structure that is expensive to traverse (like, say, file paths on a network folder, or even a local disk sometimes) -- you don&#x27;t want to expand nodes or traverse edges needlessly. However, no library that I&#x27;ve seen lets you do this. Has anyone else seen any?