| use crate::utils::{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, |
| impl_generics, |
| ty_generics, |
| where_clause, |
| member, |
| info, |
| .. |
| } = state.assert_single_enabled_field(); |
| |
| let (target, body) = if info.forward { |
| ( |
| quote!(#casted_trait::Target), |
| quote!(#casted_trait::deref(&#member)), |
| ) |
| } else { |
| (quote!(#field_type), quote!(&#member)) |
| }; |
| |
| Ok(quote! { |
| impl#impl_generics #trait_path for #input_type#ty_generics #where_clause |
| { |
| type Target = #target; |
| #[inline] |
| fn deref(&self) -> &Self::Target { |
| #body |
| } |
| } |
| }) |
| } |