Use `quote!` macro

[dtolnay]

I think the code would be a lot less confusing, especially with the double braces {{ }} all over the place. Let me know if there is a reason you chose not to do it this way originally.

Before

pub fn enum_body(name: &str, variants: &[Variant]) -> String {
    let mut body = String::new();

    write!(body, "
        if type_.name() != \"{}\" {{
            return false;
        }}

        match *type_.kind() {{
            ::postgres::types::Kind::Enum(ref variants) => {{
                if variants.len() != {} {{
                    return false;
                }}

                variants.iter().all(|v| {{
                    match &**v {{", name, variants.len()).unwrap();

    for variant in variants {
        write!(body, "
                        \"{}\" => true,", variant.name).unwrap();
    }

    write!(body, "
                        _ => false,
                    }}
                }})
            }}
            _ => false,
        }}").unwrap();

    body
}

After

pub fn enum_body(name: &str, variants: &[Variant]) -> Tokens {
    let num_variants = variants.len();
    let variant_names = variants.iter().map(|v| &v.name);

    quote! {
        if type_.name() != #name {
            return false;
        }

        match *type_.kind() {
            ::postgres::types::Kind::Enum(ref variants) => {
                if variants.len() != #num_variants {
                    return false;
                }

                variants.iter().all(|v| {
                    match &**v {
                        #(
                            #variant_names => true,
                        )*
                        _ => false,
                    }
                })
            }
            _ => false,
        }
    }
}

[sfackler]

Neat! I didn't look super closely at the quote crate when doing the initial implementation. Will update.