John Maddock wrote, On 2015-04-19 12:55:
I've added a bug report for this: https://svn.boost.org/trac/boost/ticket/11205
Thank you very much.
However, in the mean time, there is a much simpler workaround, if you use:
(?x-s) (?# free spacing, dot doesn't match newline) (?://.*+ (?# eat single-line comment text) |/\*[\S\s]*?\*/ (?# eat multi-line comment text) |"(?:\\.|[^"\n])*+" (?# eat string text) ) (?# skip these) |\b(foo)\b (?# match this)
And if $1 matched, then you have what you were looking for, otherwise discard. It's not as "neat" as the original, but is no less/more efficient.
Isn't that basically the same that I said, just changing the grouping?
Without (*SKIP), it can be done only by calling regex::search multiple >> times, using an expression like this:
(?-s)//.*+|/\*[\S\s]*?\*/|"(?:\\.|[^"\n])*+"|(\bfoo\b)
and ignoring every match where group 1 wasn't matched. That's presumed to be slower, and certainly more inconvenient for the programmer.
The match shouldn't be given up if a comment or string is found; the programmer needs to keep searching until either there's no match, or group 1 is matched. It's what I ended up doing. I presumed it would be less efficient because it's creating an additional match group per call, and because there's the set-up time and function call overhead over the multiple calls that are necessary this way. And not sure but it's possible there are more cache misses. Sei