in reply to Re^4: A NOT in regular expressions (why [^%>]?)
in thread A NOT in regular expressions

Um, no. 

$s = '1 <% xxx%%> 2 <%%> 3 <%>%> 4 <% >% %> 5 <%%%% xxx %%%%> 6 ';

$s =~ s/<% (?> [^%]+ | %+ [^>]+ )* %>/!REPLACED!/xg; 
print $s;

1 !REPLACED!%> 4 <% >% %> 5 <%%%% xxx %%%%> 6

[download]
Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller

In Section Seekers of Perl Wisdom