objekt_clonable_impl/
lib.rs

1extern crate proc_macro;
2
3use proc_macro::TokenStream;
4use quote::quote;
5
6use syn::*;
7
8#[proc_macro_attribute]
9pub fn clonable(_attrs: TokenStream, item: TokenStream) -> TokenStream {
10    let mut item_trait = parse_macro_input!(item as ItemTrait);
11
12    let item_trait_ident = &item_trait.ident;
13
14    let cloneish_paths: &[Path] =
15        &[parse_quote!(Clone), parse_quote!(std::clone::Clone), parse_quote!(::std::clone::Clone)];
16
17    if let Some(path) = item_trait
18        .supertraits
19        .iter_mut()
20        .filter_map(|x| match x {
21            TypeParamBound::Trait(ref mut y) => Some(y),
22            _ => None
23        })
24        .map(|x| &mut x.path)
25        .find(|x| cloneish_paths.iter().any(|y| &y == x))
26    {
27        *path = parse_quote!(objekt_clonable::objekt::Clone);
28    } else {
29        panic!("`Clone` must be present in trait supertrait list");
30    }
31
32    let (impl_generics, ty_generics, where_clause) = item_trait.generics.split_for_impl();
33
34    (quote! {
35        #item_trait
36        objekt_clonable::objekt::clone_trait_object!(#impl_generics #item_trait_ident #ty_generics #where_clause);
37    })
38    .into()
39}
objekt_clonable_impl/lib.rs

objekt_clonable_impl/
lib.rs
