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use crate::add_assign_like;
use crate::mul_helpers::generics_and_exprs;
use crate::utils::{AttrParams, HashSet, MultiFieldData, RefType, State};
use proc_macro2::TokenStream;
use quote::{format_ident, quote};
use std::iter;
use syn::{DeriveInput, Result};
pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
let method_name = trait_name
.to_lowercase()
.trim_end_matches("assign")
.to_string()
+ "_assign";
let mut state = State::with_attr_params(
input,
trait_name,
method_name,
AttrParams::struct_(vec!["forward"]),
)?;
if state.default_info.forward {
return Ok(add_assign_like::expand(input, trait_name));
}
let scalar_ident = format_ident!("__RhsT");
state.add_trait_path_type_param(quote! { #scalar_ident });
let multi_field_data = state.enabled_fields_data();
let MultiFieldData {
input_type,
field_types,
ty_generics,
trait_path,
trait_path_with_params,
method_ident,
..
} = multi_field_data.clone();
let tys = field_types.iter().collect::<HashSet<_>>();
let tys = tys.iter();
let trait_path_iter = iter::repeat(trait_path_with_params);
let type_where_clauses = quote! {
where #(#tys: #trait_path_iter),*
};
let (generics, exprs) = generics_and_exprs(
multi_field_data.clone(),
&scalar_ident,
type_where_clauses,
RefType::Mut,
);
let (impl_generics, _, where_clause) = generics.split_for_impl();
Ok(quote! {
#[automatically_derived]
impl #impl_generics #trait_path<#scalar_ident> for #input_type #ty_generics #where_clause {
#[inline]
fn #method_ident(&mut self, rhs: #scalar_ident) {
#( #exprs; )*
}
}
})
}