+ next_char = READCHAR;
+ if (next_char == '.')
+ {
+ /* Only a dotted-pair dot is valid after a char constant. */
+ int next_next_char = READCHAR;
+ UNREAD (next_next_char);
+
+ ok = (next_next_char <= 040
+ || (next_next_char < 0200
+ && (index ("\"';([#?", next_next_char)
+ || (!first_in_list && next_next_char == '`')
+ || (new_backquote_flag && next_next_char == ','))));
+ }
+ else
+ {
+ ok = (next_char <= 040
+ || (next_char < 0200
+ && (index ("\"';()[]#?", next_char)
+ || (!first_in_list && next_char == '`')
+ || (new_backquote_flag && next_char == ','))));
+ }
+ UNREAD (next_char);
+ if (!ok)
+ Fsignal (Qinvalid_read_syntax, Fcons (make_string ("?", 1), Qnil));
+