Why isn't there a size limit option?

[Ruttie2006]

The regex-automata crate has an option for limiting the size of the automata at build time.
This crate currently does not have such a feature (or at least, I haven't found it).
I imagine that untrusted input for needles is a somewhat common occurrence for this crate so it might be useful to add a size limit to avoid exploitation.

[BurntSushi]

regex-automata has a size limit option because the size of the input (the length of the sum of the patterns) is not proportional to the size of the compiled regex. The only reason why this is true is because of counted repetitions. i.e., .{100}{100}{100}.

But AhoCorasick doesn't support anything like that. So the way to apply a size limit is to limit the length of the patterns. Namely, the size of the resulting AhoCorasick value should be proportional to the sum of the lengths of the patterns.