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|
use crate::utils::{add_extra_where_clauses, SingleFieldData, State};
use proc_macro2::TokenStream;
use quote::quote;
use syn::{parse::Result, DeriveInput};
/// Provides the hook to expand `#[derive(Deref)]` into an implementation of `Deref`
pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
let state = State::with_field_ignore_and_forward(
input,
trait_name,
quote!(::core::ops),
trait_name.to_lowercase(),
)?;
let SingleFieldData {
input_type,
field_type,
trait_path,
casted_trait,
ty_generics,
member,
info,
..
} = state.assert_single_enabled_field();
let (target, body, generics) = if info.forward {
(
quote!(#casted_trait::Target),
quote!(#casted_trait::deref(&#member)),
add_extra_where_clauses(
&input.generics,
quote! {
where #field_type: #trait_path
},
),
)
} else {
(
quote!(#field_type),
quote!(&#member),
input.generics.clone(),
)
};
let (impl_generics, _, where_clause) = generics.split_for_impl();
Ok(quote! {
impl#impl_generics #trait_path for #input_type#ty_generics #where_clause
{
type Target = #target;
#[inline]
fn deref(&self) -> &Self::Target {
#body
}
}
})
}
|
