macroclassrender 0.0.2

use syn::{MetaItem, Lit, Field};
use quote::{Ident, Tokens};

const ATTRIBUTE_NAME: &'static str = "get_mut";
const FN_NAME_PREFIX: &'static str = "get_mut";
const FN_NAME_SUFFIX: &'static str = "";

pub fn implement(field: &Field) -> Tokens {
    let field_name = field.clone().ident.expect("Expected the field to have a name");
    let fn_name = Ident::from(format!("{}{}{}", FN_NAME_PREFIX, field_name, FN_NAME_SUFFIX));
    let ty = field.ty.clone();

    let attr = field.attrs.iter()
        .filter(|v| v.name() == ATTRIBUTE_NAME)
        .last();

    let doc = field.attrs.iter()
        .filter(|v| v.name() == "doc")
        .collect::<Vec<_>>();

    match attr {
        Some(attr) => {
            match attr.value {
                // `#[get]`
                MetaItem::Word(_) => {
                    quote! {
                        #(#doc)*
                        fn #fn_name(&mut self) -> &mut #ty {
                            &mut self.#field_name
                        }
                    }
                },
                // `#[get = "pub"]`
                MetaItem::NameValue(_, Lit::Str(ref s, _)) => {
                    let visibility = Ident::from(s.clone());
                    quote! {
                        #(#doc)*
                        #visibility fn #fn_name(&mut self) -> &mut #ty {
                            &mut self.#field_name
                        }
                    }
                },
                _ => panic!("Unexpected attribute parameters."),
            }
        },
        // Don't need to do anything.
        None => quote! { }
    }
}