diff options
Diffstat (limited to 'third_party/rust/derive_more-impl/src/index_mut.rs')
-rw-r--r-- | third_party/rust/derive_more-impl/src/index_mut.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/third_party/rust/derive_more-impl/src/index_mut.rs b/third_party/rust/derive_more-impl/src/index_mut.rs new file mode 100644 index 0000000000..0e030cf6f5 --- /dev/null +++ b/third_party/rust/derive_more-impl/src/index_mut.rs @@ -0,0 +1,44 @@ +use crate::utils::{add_where_clauses_for_new_ident, SingleFieldData, State}; +use proc_macro2::TokenStream; +use quote::{format_ident, quote}; +use syn::{parse::Result, DeriveInput}; + +/// Provides the hook to expand `#[derive(IndexMut)]` into an implementation of `IndexMut` +pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> { + let index_type = format_ident!("__IdxT"); + let mut state = State::with_field_ignore(input, trait_name, "index_mut".into())?; + state.add_trait_path_type_param(quote! { #index_type }); + let SingleFieldData { + field, + field_type, + input_type, + trait_path_with_params, + casted_trait, + member, + .. + } = state.assert_single_enabled_field(); + + let type_where_clauses = quote! { + where #field_type: #trait_path_with_params + }; + + let new_generics = add_where_clauses_for_new_ident( + &input.generics, + &[field], + &index_type, + type_where_clauses, + true, + ); + + let (impl_generics, _, where_clause) = new_generics.split_for_impl(); + let (_, ty_generics, _) = input.generics.split_for_impl(); + Ok(quote! { + #[automatically_derived] + impl #impl_generics #trait_path_with_params for #input_type #ty_generics #where_clause { + #[inline] + fn index_mut(&mut self, idx: #index_type) -> &mut Self::Output { + #casted_trait::index_mut(&mut #member, idx) + } + } + }) +} |