Re: [Boost-users] [Regex] How to use BOOST_REGEX_RECURSIVE

From: John Maddock (john_at_[hidden])
Date: 2008-05-20 03:55:24

Richard Hadsell wrote:
> I just discovered the Regex algorithm selection macros that have been
> around for a long time.  I noticed that BOOST_REGEX_RECURSIVE is
> supposed to enable a faster algorithm, and it is not the default on
> Linux systems.  Most of our patterns are very simple, so I am not
> worried about pathological cases, and I would like to try the
> recursive algorithm.
>
> Do I need to modify boost/regex/user.hpp before building the library?

Yes.

> Do I need to compile my applications with the macro defined as a
> compiler option?

Not if you've changed user.hpp.

> Is it sufficient to define the macro in a source file before including
> the boost/regex.h header?

No the library has to built with the same options as you use in your 
application.

BTW the performance difference between the recursive and non-recursive 
algorithms is actually quite small.

HTH, John.