derive_more/
add_assign_like.rs

1use crate::add_helpers::{struct_exprs, tuple_exprs};
2use crate::utils::{add_extra_ty_param_bound_op, named_to_vec, unnamed_to_vec};
3use proc_macro2::{Span, TokenStream};
4use quote::quote;
5use syn::{Data, DeriveInput, Fields, Ident};
6
7pub fn expand(input: &DeriveInput, trait_name: &str) -> TokenStream {
8    let trait_ident = Ident::new(trait_name, Span::call_site());
9    let method_name = trait_name.to_string();
10    let method_name = method_name.trim_end_matches("Assign");
11    let method_name = method_name.to_lowercase();
12    let method_ident = Ident::new(&(method_name + "_assign"), Span::call_site());
13    let input_type = &input.ident;
14
15    let generics = add_extra_ty_param_bound_op(&input.generics, &trait_ident);
16    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
17
18    let exprs = match input.data {
19        Data::Struct(ref data_struct) => match data_struct.fields {
20            Fields::Unnamed(ref fields) => {
21                tuple_exprs(&unnamed_to_vec(fields), &method_ident)
22            }
23            Fields::Named(ref fields) => {
24                struct_exprs(&named_to_vec(fields), &method_ident)
25            }
26            _ => panic!("Unit structs cannot use derive({})", trait_name),
27        },
28
29        _ => panic!("Only structs can use derive({})", trait_name),
30    };
31
32    quote!(
33        impl#impl_generics ::core::ops::#trait_ident for #input_type#ty_generics #where_clause {
34            #[inline]
35            fn #method_ident(&mut self, rhs: #input_type#ty_generics) {
36                #(#exprs;
37                  )*
38            }
39        }
40    )
41}
derive_more/add_assign_like.rs

derive_more/
add_assign_like.rs
