# Define base variable detector: any (possibly-nested) angle-bracketed string.
# Patterns to extract <variables> or >variables< from a string.
my $out_angled;
$out_angled = qr/ < ( [^<>] | (??{$out_angled}) )* > /x;
                  # open angle-bracket then ...
                      # non-angle chars ...
                            # or ...
                               # another angle-bracketed item ...
                                                 # if there are any ...
                                                   # and a close angle-bracket

##</code><code>##

$templaty = qr/
                \[%                # open delim
                     (
                        (?!%\])    # not-a-closer lookahead
                        .          # anything else
                      )*           # as many as  there are
                 %\]               # close delim
           /x;
@vars = ($string =~ $templaty);