On Wed, 5 Jun 2019, ND via Pcre-dev wrote: > May be there is a some space for optimization there. > > PCRE analyze subpattern in lookaround and say: > First code unit = 'a' > Last code unit = 'c' > > So it already knows that "Subject length lower bound" is greater than 0. > Isn't it?
Yes, that's true; it could easily set the lower bound to 2 from that information. I will taks a look at that. Thanks for the idea, though it can only be of small benefit as it will cut out only 2 match attempts. The subject length optimization does not do very deep analysis. It is cheap code that makes a useful difference in many cases without too much work. To handle lookarounds fully would be more complicated and would benefit only a few cases where a positive lookahead reads more than what follows. Philip -- Philip Hazel -- ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev
