Why is Xpressive more readable than using lexical_cast or your numeric_cast? I've implemented specializations of lexical_cast for string->numeric conversions using strto[ld]. It is a vast speed improvement of course, and since those specializations are hidden away in a header, readability is the same as with normal lexical_casts. Maybe I'm misunderstanding your use case? Do you not know ahead of time what the type of the number will be? -Matt Dave Jenkins wrote:
Whoa! The performance just shot up to a mere 6X the custom code (from 175X). That might well be fast enough to keep the Xpressive version because of its readability!
Can you create thread-local match_results objects and reuse them? If so, I think you'll see parsing dwindle to almost nothing and your semantic actions will account for the bulk of the time spent.
Regards, Dave Jenkins