# Macro synom::option [−] [src]

    macro_rules! option {
        ($i:expr, $submac:ident!( $($args:tt)* )) => { ... };
        ($i:expr, $f:expr) => { ... };
    }

Turn a failed parse into `None` and a successful parse into `Some`.

- Syntax: `option!(THING)`
- Output: `Option<THING>`

    extern crate syn;
    #[macro_use] extern crate synom;

    named!(maybe_bang -> Option<&str>, option!(punct!("!")));

    fn main() {
        let input = "!";
        let parsed = maybe_bang(input).expect("maybe bang");
        assert_eq!(parsed, Some("!"));

        let input = "";
        let parsed = maybe_bang(input).expect("maybe bang");
        assert_eq!(parsed, None);
    }

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