Noel Jones wrote:
> Many years ago I worked on a system with a 32k limit on pcre
> expressions. Ever since then, everything I've checked has
> been 64k, and then I gave up checking. I expect any
> non-ancient system will support 64k, and some maybe even more.
> (To clarify for others following along, this is a characters
> per single expression limit, not a filesize or number of
> expressions per file limit)
Thanks for the info.
> > Now compare that against:
> >
> > /^([0-9]{1,3}\.){4}(foo|bar|baz)$/
> >
> > which will again fail on the fourth character, but there is only one
> > pattern which matches the same strings as the 3 patterns above.
>
> This example is pretty easy to see that combining is better.
Exactly. Fortunately this is the very common example that will
very easily lend itself to this optimisation.
> It's not so clear if you create 32k of complex gibberish if it
> will actually operate faster as there may be significant
> startup times. YMMV and all that.
I agree completely.
> BTW, with pcre you should use the the non-greedy flag inside
> parenthesis if you're not doing $n substitutions. This saves
> another smidgen of time and memory.
> /^(?:[0-9]{1,3}\.){4}(?:foo|bar|baz)$/
Good tip, thanks.
Erik
--
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Erik de Castro Lopo
http://www.mega-nerd.com/
