Enums

Much like structs, enums can be used as consumable types. Astray will try to parse each of the enum's variants from top to bottom. If all variants fail to parse, the enum fails to parse If at least one variant does parse, the enum parsing succeeds All enums derive SN, as long as they follow the guidelines in the notes below:

Enum Note 1: Unit variants must have a #[pat] attribute annotation

#![allow(unused)]
fn main() {
/*valid*/
#[derive(SN)]
enum Sign {
    #[pat(Token::Plus)]
    Plus,
    #[pat(Token::Minus)]
    Minus,
}

/*invalid, fails to compile*/
#[derive(SN)]
enum Sign {
    Plus,
    Minus,
}
}

Enum Note 2: Single Tuple variants only

Use single element tuple variants that contain a tuple instead of tuple variants with many elements.

#![allow(unused)]

fn main() {
enum Sign {
    #[pat(Token::Plus)]
    Plus(Token),
    // valid 
    #[pat(Token::Slash)]
    Div((Token)),
    // invalid, fails to compile 
    IntegerDiv(Token, Token),
    // valid, applies pattern to tuple
    #[pat((Token::Slash, Token::Slash))]
    IntegerDiv((Token, Token)),
}
}

struct variants are not supported yet

TODO: Add support for this and mention tracking issue here