RE: [boost] Wave C++ Review Begins Today - February 7, 2005

From: Hartmut Kaiser (HartmutKaiser_at_[hidden])
Date: 2005-02-10 07:01:42

Dan Nuffer wrote:

> It is possible to use re2c generated code in a c++ context.  
> However, to explain the current situation, the original re2c 
> c++ lexer was actually written in pure C (thus the origin of 
> the aq_* code), and it looks like Hartmut has only changed 
> the minimum necessary to integrate it with Wave. Like he 
> said, if it works, don't mess with it :-)

Yes, I've written minimal interfacing code only. Nevertheless I had to
change the lexer itself (mainly the token regex's) quite a bit.

> I originally wrote the re2c c++ scanner as a benchmarking 
> tool to compare performance of re2c/flex/SLex generated 
> scanners.  At the time re2c won by about a factor of 2 IIRC.  
> I did it in C because my #1 goal was performance.  I found it 
> interesting that, using the exact same source, if I compiled 
> it as C instead of C++, it was about 10% faster.
> But that was years ago with gcc 2.95.2, who knows how things 
> would stand today?

I haven't obversed such a runtime difference during my tests, but what I do
have observed is a significant compile time difference in about factor 10
and more (between the compilation of the re2c generated giant switch
statement with a C and a C++ compiler).

Regards Hartmut