Alex Shinn scripsit:
It's awfully handy for things like /<([a-zA-Z][a-zA-Z0-9-]*>[^<]*</\1>/,
> Expensive is the O(n^3) for the next step up the Chomsky hierarchy.
> I think exponential warrants the use of "prohibitively." The feature
> is included mostly for completeness, for round-trip conversion from
> existing PCRE libraries, and I think the advice that it should never
> actually be used is warranted.
though (given some restrictions that often apply in practice, like no
recursive elements and no non-ASCII element names).