diff options
Diffstat (limited to 'third_party/rust/derive_more-impl/src/deref.rs')
-rw-r--r-- | third_party/rust/derive_more-impl/src/deref.rs | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/third_party/rust/derive_more-impl/src/deref.rs b/third_party/rust/derive_more-impl/src/deref.rs new file mode 100644 index 0000000000..f87c64cc61 --- /dev/null +++ b/third_party/rust/derive_more-impl/src/deref.rs @@ -0,0 +1,55 @@ +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, + 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! { + #[automatically_derived] + impl #impl_generics #trait_path for #input_type #ty_generics #where_clause { + type Target = #target; + + #[inline] + fn deref(&self) -> &Self::Target { + #body + } + } + }) +} |