ruby-special-char-p
ruby-special-char-p is a compiled Lisp function in `ruby-mode.el
'.
(ruby-special-char-p &optional POS)
Return t if the character before POS is a special character.
If omitted, POS defaults to the current point.
Special characters are `?', `$', `:' when preceded by whitespace,
and `\' when preceded by `?'.