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http://bugs.exim.org/show_bug.cgi?id=1372 --- Comment #6 from Philip Hazel <[email protected]> 2013-07-28 11:31:54 --- (In reply to comment #5) > My thinking was that implementing such additions won't be that onerous, the > reason being that there is already an implementation for alternation. The > difference is that, in alternation, subexpressions (alternates) are executed > left to right against the subject text until one succeeds, or all fail > (implementing a boolean OR), while a boolean AND involves executing alternates > left to right against the subject text until one fails, or all succeed. So > it's > rather the way to compound the partial results that differs, than the way to > compute them. The implementation isn't quite like that. For something like (A|B|C)D it will immediately go on to check D once A succeeds; only if D fails will it back up to try B. To implement AND would mean stopping after matching A and checking B and C before moving on to D. This is similar to what happens for a lookahead, however (which is not surprising, since you can get the AND behaviour using lookaheads). > I am sure that you know better what are the priorities, and just want to take > the opportunity to say a big THANK YOU for the wonderful tool you are offering > to so many to help us accomplish what we need to accomplish. Thank you. Maybe once we have got the new API sorted out I might find time to research what other regex packages do about AND. -- Configure bugmail: http://bugs.exim.org/userprefs.cgi?tab=email -- ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev
