dyn_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 = &[quote!(Clone), quote!(std::clone::Clone), quote!(::std::clone::Clone)];
15
16    if let Some(path) = item_trait
17        .supertraits
18        .iter_mut()
19        .filter_map(|x| match x {
20            TypeParamBound::Trait(y) => Some(y),
21            _ => None
22        })
23        .map(|x| &mut x.path)
24        .find(|x| {
25            let s = quote!(#x).to_string();
26            cloneish_paths.iter().any(|y| y.to_string() == s)
27        })
28    {
29        *path = parse_quote!(dyn_clonable::dyn_clone::DynClone);
30    } else {
31        panic!("`Clone` must be present in trait supertrait list");
32    }
33
34    let (impl_generics, ty_generics, where_clause) = item_trait.generics.split_for_impl();
35
36    (quote! {
37        #item_trait
38        dyn_clonable::dyn_clone::clone_trait_object!(#impl_generics #item_trait_ident #ty_generics #where_clause);
39    })
40    .into()
41}
dyn_clonable_impl/lib.rs

dyn_clonable_impl/
lib.rs
