May 26, 2018
Partial ordering for regular expressions
RegexpCompare implements a function comparing regular expressions it returns true if all strings matched by the first regexp are also matched by the second. It’s meant to be used for optimization of blacklists implemented by regular expressions like, for example, http//www.communitywiki.org/cw/BannedContent.
False return value does not imply that there’s a string matched by the first regexp which isn’t matched by the second - many regular expressions i.e. those containing Perl code are impossible to compare, and this module doesn’t even implement all possible comparisons.