| use add_like::{struct_exprs, tuple_exprs}; |
| use proc_macro2::{Span, TokenStream}; |
| use syn::{Data, DeriveInput, Fields, Ident}; |
| use utils::{add_extra_ty_param_bound_op, named_to_vec, unnamed_to_vec}; |
| |
| pub fn expand(input: &DeriveInput, trait_name: &str) -> TokenStream { |
| let trait_ident = Ident::new(trait_name, Span::call_site()); |
| let method_name = trait_name.to_string(); |
| let method_name = method_name.trim_right_matches("Assign"); |
| let method_name = method_name.to_lowercase(); |
| let method_ident = Ident::new(&(method_name.to_string() + "_assign"), Span::call_site()); |
| let input_type = &input.ident; |
| |
| let generics = add_extra_ty_param_bound_op(&input.generics, &trait_ident); |
| let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); |
| |
| let exprs = match input.data { |
| Data::Struct(ref data_struct) => match data_struct.fields { |
| Fields::Unnamed(ref fields) => tuple_exprs(&unnamed_to_vec(fields), &method_ident), |
| Fields::Named(ref fields) => struct_exprs(&named_to_vec(fields), &method_ident), |
| _ => panic!(format!("Unit structs cannot use derive({})", trait_name)), |
| }, |
| |
| _ => panic!(format!("Only structs can use derive({})", trait_name)), |
| }; |
| |
| quote!( |
| impl#impl_generics ::std::ops::#trait_ident for #input_type#ty_generics #where_clause { |
| #[inline] |
| fn #method_ident(&mut self, rhs: #input_type#ty_generics) { |
| #(#exprs; |
| )* |
| } |
| } |
| ) |
| } |