impl<T: Logos> CallbackResult for T

[ExoticMatter]

With this patch, you can return tokens directly from callbacks--but only for unit variants. Closes #294. Related to #245.

#[derive(Logos, Debug, PartialEq)]
#[logos(skip r"[ \t\n\f]+")]
enum Token {
    #[regex(r"[a-zA-Z]+", |_| Token::Text)]
    #[regex(r"-?[0-9]+", |_| Token::Integer)]
    #[regex(r"-?[0-9]+\.[0-9]+", |_| Token::Float)]
    Text,
    Integer,
    Float,
}

[maciejhirsz]

Out of curiosity, do you have an example where that's something you'd do? It's always helpful to see user code for insights I might not have otherwise.

The PR looks fine to me by itself.

[ExoticMatter]

In my case it was for Python-like formatting. Indent, Dedent, and NewLine need to be distinct tokens, but they all share the same regex so they can't have separate callbacks.

[maciejhirsz]

Ah interesting! Makes sense, and thank you for the PR!