Another RFC: regex in libiberty

Jim Blandy
Tue Jun 12 06:48:00 GMT 2001

Jim Blandy <> writes:
> To generate every possible match, you have to choose every possible
> way to divide up those twenty a's amongst six .* patterns.  I think
> this is 20 choose 5, or 1.9 million, matches you have to try.  In
> general, I think the time to match POSIXly can increase exponentially
> in the length of your regexp, given a long enough data string.

20 choose 5 is, of course, only 15504, not 1.9 million.  Oops.

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