#!perl

while (<DATA>)
{
  chomp;
  print "for [$_]:\n";
  # split on XX, but only when it's not in
  # single quotes.
  while (m% ((?:[^']*?         # Some unquoted stuff
                 (?:'[^']*')?  # optional quoted stuff
              )*?)             # many times, but non-greedy
           XX |                # field separator, or
            (.+) %xg)          #   a non-blank final field
  {
    # field value should now be in defined($2)?$2:$1
    my ($t1, $t2) = qw(undef undef);
    $t1 = "[$1]" if defined($1);
    $t2 = "[$2]" if defined($2);
    print "\t$t1\t$t2\n";
  }
}
__END__
aXXbXXc
abcd
a little 'quote XX' quote stuff XX other


##</code><code>##

for [aXXbXXc]:
        [a]     undef
        [b]     undef
        undef   [c]
for [abcd]:
        undef   [a]
        undef   [b]
        undef   [c]
        undef   [d]
for [a little 'quote XX' quote stuff XX other]:
        [a little 'quote XX' quote stuff ]      undef
        undef   [ ]
        undef   [o]
        undef   [t]
        undef   [h]
        undef   [e]
        undef   [r]


##</code><code>##

#!perl

while (<DATA>)
{
  chomp;
  print "for [$_]:\n";
  # split on XX, but only when it's not in
  # single quotes.
  while (m% ([^']*?         # Some unquoted stuff
             (?:'[^']*'     # optionally, quoted followed by 
                 [^']*?)*? )# unquoted stuff.  non-greedy
           XX |             # field separator, or
            (.+) %xg)       #   a non-blank final field
  {
    # field value should now be in defined($2)?$2:$1
    my ($t1, $t2) = qw(undef undef);
    $t1 = "[$1]" if defined($1);
    $t2 = "[$2]" if defined($2);
    print "\t$t1\t$t2\n";
  }
}
__END__
aXXbXXc
abcd
a little 'quote XX' quote stuff XX other


##</code><code>##

--
@/=map{[/./g]}qw/.h_nJ Xapou cets krht ele_ r_ra/;
map{y/X_/\n /;print}map{pop@$_}@/for@/