($quote, $quoted, undef, $unquoted, $delim, undef) =
    $line =~ m/^(["'])                 # a $quote
              ((?:\\.|(?!\1)[^\\])*)   # and $quoted text
              \1                       # followed by the same quote
              ([\000-\377]*)           # and the rest
              |                        # --OR--
              ^((?:\\.|[^\\"'])*?)     # an $unquoted text
              (\Z(?!\n)|(?-x:$delimiter)|(?!^)(?=["']))
                                       # plus EOL, delimiter, or quote
              ([\000-\377]*)           # the rest
              |                        # --OR--
              ($delimiter)
              /x;                      # extended layout