Stewart, Robert wrote:
I was experimenting with Xpressive to see how it would compare with some custom, string-based numeric input parsing. The Xpressive code is over 175X slower than the custom code. Have I done anything to make it really slow? Can it be made faster? <snip>
Where is the code against which you are benchmarking? From looking at the code, I can see a few areas for improvement. With each call to parse(), you construct and discard a match_results object. For optimal performance, you should reuse the match_results object to avoid extra memory allocation. Also, many of the quantifiers in your grammar do not require backtracking, so you could use keep() to turn backtracking off selectively. That's all I have for now. -- Eric Niebler BoostPro Computing http://www.boostpro.com