use strict;
my $line = join ",",
  (
	'"completely quoted"',
	'not quoted',
	'partially "quoted"',
	'"completely quoted with embedded, comma"',
	'partially "quoted with embedded, comma"',
	'quote \'and comma, inside " single\' quote',
	'single quote "and comma, inside of \' double" quote',
	'last'
  );

my $re = qr/((?:[^"',]|"[^"]*"|'[^']*')+)/;

print(">$_<\n") for $line =~ /$re/g;

##</code><code>##

>"completely quoted"<
>not quoted<
>partially "quoted"<
>"completely quoted with embedded, comma"<
>partially "quoted with embedded, comma"<
>quote 'and comma, inside " single' quote<
>single quote "and comma, inside of ' double" quote<
>last<

##</code><code>##

one,,three