I'm implementing a grammar that has some rules like this:
char-literal ::= ' regular-char '
∣ ' escape-sequence '
escape-sequence ::= \ ( \ ∣ " ∣ ' ∣ n ∣ t ∣ b ∣ r ∣ space )
∣ \ (0…9) (0…9) (0…9)
∣ \x (0…9∣ A…F∣ a…f) (0…9∣ A…F∣ a…f)
The point is that, I don't know how to define character literal using Irony. Any idea?