[WIP] Implement enum variants

[Kijewski]

Resolves #223.

[GuillaumeGomez]

Might be better to name it Struct since we don't support unions currently.

[Kijewski]

Changed.

[GuillaumeGomez]

It's super weird. What about:

Suggested change

	if let dest @ None = access(dest) {
	if access(dest).is_none() {

?

[Kijewski]

It's the same as let dest = access(dest); if dest.is_none() { in one line. I found it nifty. :) But changed.

[GuillaumeGomez]

So if I understand correctly, when a variant has a #[template()] attribute, we generate a struct representing it then call render/render_into() on this struct, right?

Very hypothetical (and in case I understood everything correctly up to this point): isn't it possible to instead handle the variant like we handle our structs. Trying to explain in code:

#[template(src = "boo.txt")]
enum Foo {
    A,
    #[template(src = "I-am-b.txt")]
    B(u32, u32),
    #[template(src = "not-boo.txt")]
    C { a: u32 },
}

impl Render for Foo {
    fn render(&self) -> Result<String> {
        match self {
            // First the variants with the template
            B(_0, _1) => {
                // this one needs a struct binding :'(
            }
            C { a } => {
                // We can re-use the code for structs where we can say that this is a struct with a field named `a` and tada.
            }
        }
    }
}

Not sure if it's a good idea though... That would allow to skip a type creation for one case. But then self.a wouldn't work. So I think overall I just had a terrible idea. ^^'

[Kijewski]

Yep, I implemented it this way so that self.x still works. I'd let the compile/optimizer decide if it's good idea to inline everything into one big function or if the implementations for every variant should stay.

[GuillaumeGomez]

Please tell me when it's ready for final review. ;)

(also git conflict)