http://www.perlmonks.org?node_id=1005478


in reply to Regex to compare (if) two strings (Uniquely - I will explain inside)

In a similar vein to this, another regex approach. I hesitate to offer it because I'm not sure the increased complexity pays off. More effort is spent in building the thing, but despite being significantly larger, the final regex may run more quickly versus the repeated compilation and invocation of the shorter  s/// of the previous link. However, it may take operation on rather long strings for any advantage to become manifest. I have done no benchmarking, but at least it's tested and works. The dreams of regexen produce monsters.

sub scrabblicious { my ($word, # word to test for proper match to tray of letters $tray, # string with 'tray' of letters to select from ) = @_; return unless # handles word empty string (my $rx = join '', sort split '', $word) =~ s{ (.) \1* } { $+[0] - $-[0] > 1 ? qq/(?= (?: .*? \Q$1\E){@{[ $+[0] - $-[0] ]}})/ : qq/(?= .*? \Q$1\E)/ }xmseg; return $tray =~ m{ \A $rx }xms; }