Re: [Boost-users] cancel a pending cregex_iterator matching

From: John Maddock (john_at_[hidden])
Date: 2007-01-19 04:41:10

Winson Yung wrote:
> Hello, I am using the following pesudo code to do a regex match on big
> buffer (25K of text), sometimes it takes a little longer to come back
> with a result. I know this partly because the way my regular
> expression pattern is structured, but I am just wondering whether
> boost::regex has a mechanism to cancel the pending matching like this
> one.

Well 25K isn't a very large buffer :-)  There is no method to 
"asynchronously cancel" a search operation once you start it.  However, 
there is a failsafe built into Boost.Regex that will cause a 
std::runtime_error to be thrown if the complexity of finding a match grows 
too large, or takes too long.  See the test programs under 
libs/regex/test/pathology for examples.  If the default failsafes don't kick 
in early enough for you, then you may be able to tweek the headers (grep for 
estimate_max_state_count) to force cancellation to occur earlier: although 
of course you may find this causes perfectly good expressions to fail if you 
overdo it.

HTH, John.