Controversial opinion time: The advantages of Thompson NFA regexes are just theoretical and not worth it. PCRE is faster in the real world.
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Replying to @pcwalton
It's pretty funny you post this just after Cloudflare inflicted a major outage on half the world due to a pathologically backtracking regex. This opinion is fractally wrong - wrong at every level of magnification. PCRE is slower than modern automata-based regular expressions...pic.twitter.com/f343vgGZgU
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Replying to @geofflangdale @pcwalton
in the extreme pathological case but also on average cases, as both determinization and bitwise implementations are way faster than backtracking. The advantage of PCRE and backtracking is expressiveness, not speed. I don't know whether you're trolling here or just woefully ...
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Replying to @geofflangdale @pcwalton
underinformed. You're also wrong elsewhere on the thread where you claim that you need to have user-provided regexes to find a regex DDoS. It was, historically, not hard to find rules in the VRT set or the public Snort set that could have handcrafted input that would ...
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Replying to @geofflangdale @pcwalton
case the system to time out. Back in 2008-2009 or so, we found a regex where every "<" added would double the processing time in the public Snort set. Best of all, those systems *failed open* if they timed out, so in theory, if you could get a threat through that has such a ...
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Replying to @geofflangdale
The post you’re responding to is from 2014. I readily admit that
@burntsushi5’s Rust regex implementation proved me wrong.2 replies 0 retweets 0 likes -
Note that the context behind that post is from experience with SpiderMonkey’s JS regex implementation and in particular how it gets benchmarked. For JS regex benchmarks it is all about how quickly you can JIT the regex to something reasonable.
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Replying to @pcwalton @burntsushi5
If I was silly enough to return to the world of regex (having been - ahem - granted my freedom by Intel) I think working with something where speed of starting to match an entirely unknown regex is paramount would be interesting. The world of Hyperscan, particularly, assumes ...
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JS compilers are somewhat frustrating to work on because most of the clever optimizations you want to implement end up not being worth it, because speed of compilation >>> everything else :(
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