From: "Stewart, Robert" <Robert.Stewart@sig.com>
Your hopes were justified: I just noticed that while my TLS accessor returns a reference to the smatch, I saved it to a copy rather than a reference where I was using it. Correcting that mistake shows the Xpressive code taking around 1.5X the time used by the custom code.
I've seen added more test cases and updated the custom code and must now correct some things in the Xpressive code to handle all of the same cases before I can do any more measurements.
Thanks for doing this work Rob. It's been a really fruitful exercise. I had one other question on performance improvement, mostly for Eric. Could you eliminate/minimize the need for match_results when semantic actions are capturing the results? In Rob's code, he's not even looking at the match_results because his semantic actions handle the data. Can you optionally turn off the match_results capture in that case to save space and time? Regards, Dave Jenkins P.S. If I'm slow to respond, it's because I'm on vacation and internet access is spotty.