Re^3: regex step counting

> not Perl, but a very limited subset of Java's regex

I was afraid you'd say this, different engines do different guessing and optimizations.

Something very fast in Perl can be a nightmare elsewhere, and vice versa.

> I don't really need 100% accurate count of how many steps they are taking, just an idea if they are in the region of up to a few hundred steps per line

It really depends on how limited your grammar is.

The point why I mentioned the halting problem is, that the proof shows a way to construct a pathological case for every approach.

In other words, if your tests are limited it's possible to construct a troublesome regex which will pass them. (Provided the grammar is rich enough)°

Hence no guaranties whatsoever!

Good luck! :)

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice}

°) actually it's pretty trivially done, if the regex has no length restriction.

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