Boost C++ Libraries: Ticket #5215: regex_match is giving a performance hit.

version changed

anonymous — Fri, 25 Feb 2011 05:38:13 GMT

version Boost 1.34.0 → Boost 1.46.0

anonymous — Mon, 28 Feb 2011 09:42:42 GMT

Can you please provide some example code that illustrates the problem?

Please also bare in mind that matching a regular expression is in the general case NP-complete. Assuming it doesn't change the semantics of your program then something like:

/Volumes/[^/]*/Backups.backupdb/.*

Should be more efficient. Otherwise try something like:

/Volumes(?:/[^/]*)+?/Backups.backupdb/.*

anonymous — Tue, 01 Mar 2011 09:32:46 GMT

Replying to anonymous:

Can you please provide some example code that illustrates the problem?

Please also bare in mind that matching a regular expression is in the general case NP-complete. Assuming it doesn't change the semantics of your program then something like:

/Volumes/[^/]*/Backups.backupdb/.*

Should be more efficient. Otherwise try something like:

/Volumes(?:/[^/]*)+?/Backups.backupdb/.*

Thanks for the reply.

After I posted this issue, I was trying out different alternatives and found something. The back drop for this issue is that, I am getting exclusion list from the User, based on which I am performing some operations. So I convert the exclusion list to an 'expression' and pass it to regex_match(). The more I add exclusion's , more time is taken by regex_match(). As suggested by I would provide an example code that would illustrate the problem.

Thanks.

status changed; resolution set

John Maddock — Sat, 07 Jul 2012 18:10:34 GMT

status new → closed
resolution → wontfix

Closed pending update from user.