On Wed, Jul 21, 2010 at 10:52 PM, Eric Niebler
On 7/21/2010 2:39 PM, Pavol Supa wrote:
Hi,
I need to match a hex-written byte array, optionally separated with spaces. So i tried:
boost::xpressive::sregex r = * ( * blank >> repeat<2,2> (xdigit)); smatch match; regex_match (input, match, r);
when i use input of approx. 150 hex pairs, i get an exception "Regex stack space exhausted" (i use default stack size by Visual studio 2008)
This pattern looks quite simple, so I'd like to know, if there is some fundamental problem with this expressions.
Yes. See http://www.boost.org/doc/libs/1_43_0/doc/html/xpressive/user_s_guide.html#bo...
Not only will this pattern tear through stack, it'll run very slowly. Try this instead:
* ( keep(*blank) >> repeat<2,2> (xdigit))
So, i tried it. It throws exceptions at ~230 hexdigit pairs. I played with "keep"s, the only 'better' combination is * keep ( (*blank) >> repeat<2,2> (xdigit)) which throws when input has 300 pairs
I know i can enlarge the stack manually, but i expect the input to be cca 10kB long, depending on user input, so i consider it not being a good solution.
-- Eric Niebler BoostPro Computing http://www.boostpro.com _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users