derive_more_impl/
deref.rs

1use crate::utils::{add_extra_where_clauses, SingleFieldData, State};
2use proc_macro2::TokenStream;
3use quote::quote;
4use syn::{parse::Result, DeriveInput};
5
6/// Provides the hook to expand `#[derive(Deref)]` into an implementation of `Deref`
7pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
8    let state = State::with_field_ignore_and_forward(
9        input,
10        trait_name,
11        trait_name.to_lowercase(),
12    )?;
13    let SingleFieldData {
14        input_type,
15        field_type,
16        trait_path,
17        casted_trait,
18        ty_generics,
19        member,
20        info,
21        ..
22    } = state.assert_single_enabled_field();
23
24    let (target, body, generics) = if info.forward {
25        (
26            quote! { #casted_trait::Target },
27            quote! { #casted_trait::deref(&#member) },
28            add_extra_where_clauses(
29                &input.generics,
30                quote! {
31                    where #field_type: #trait_path
32                },
33            ),
34        )
35    } else {
36        (
37            quote! { #field_type },
38            quote! { &#member },
39            input.generics.clone(),
40        )
41    };
42    let (impl_generics, _, where_clause) = generics.split_for_impl();
43
44    Ok(quote! {
45        #[automatically_derived]
46        impl #impl_generics #trait_path for #input_type #ty_generics #where_clause {
47            type Target = #target;
48
49            #[inline]
50            fn deref(&self) -> &Self::Target {
51                #body
52            }
53        }
54    })
55}
derive_more_impl/deref.rs

derive_more_impl/
deref.rs
