>perl -wMstrict -le
"my $string =
   qq{uuu\tvvv\t'www\t\t'\txxx\t'\t\tyyy'\tzzz\n};
 print qq{$string};
 ;;
 $string =~
   s{ ( ' [^\\']* (?: \\. [^\\']*)* ' )        }
    { (my $notabs = $1) =~ tr{\t}{}d;  $notabs }xmsge;
 ;;
 print qq{$string};
"
uuu     vvv     'www            '       xxx     '               yyy'    zzz

uuu     vvv     'www'   xxx     'yyy'   zzz