c:\@Work\Perl\monks>perl -wMstrict -le
"my %dic = qw(Abc Zyx  Abcd Zyxw  Abcde Zyxwv);
 ;;
 use constant S => 'AbcAbcdAbcdeAbcdeAbcdAbc';
 ;;
 print '------------';
 my ($rx_A) =
   map  qr{ $_ }xms,
   join ' | ',
   sort
   map  quotemeta,
   keys %dic
   ;
 print qq{rx_A: $rx_A};
 ;;
 my $s = S;
 print qq{'$s'};
 $s =~ s{ ($rx_A) }{$dic{$1}}xmsg;
 print qq{'$s'};
 ;;
 print '------------';
 my ($rx_D) =
   map  qr{ $_ }xms,
   join ' | ',
   reverse sort
   map  quotemeta,
   keys %dic
   ;
 print qq{rx_D: $rx_D};
 ;;
 $s = S;
 print qq{'$s'};
 $s =~ s{ ($rx_D) }{$dic{$1}}xmsg;
 print qq{'$s'};
"
------------
rx_A: (?^msx: Abc | Abcd | Abcde )
'AbcAbcdAbcdeAbcdeAbcdAbc'
'ZyxZyxdZyxdeZyxdeZyxdZyx'
------------
rx_D: (?^msx: Abcde | Abcd | Abc )
'AbcAbcdAbcdeAbcdeAbcdAbc'
'ZyxZyxwZyxwvZyxwvZyxwZyx'