42 lines
1.4 KiB
Rust
42 lines
1.4 KiB
Rust
use quote::quote;
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use syn::{parse_macro_input, parse_quote, DeriveInput, GenericParam, Generics};
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#[proc_macro_derive(SharedFunctorAny)]
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pub fn derive_shared_functor(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
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let input = parse_macro_input!(input as DeriveInput);
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let name = input.ident;
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let generics = add_clone_bounds(input.generics);
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let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
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let expanded = quote! {
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impl #impl_generics SharedFunctorAny for #name #ty_generics #where_clause {
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type SharedAny<'a, A: 'a + Send + Sync + Clone> = Self::FAny<'a, A>
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where
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Self: 'a;
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fn share<'a, A: 'a + Send + Sync + Clone>(fa: Self::FAny<'a, A>) -> Self::SharedAny<'a, A>
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where
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Self: 'a,
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{
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fa
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}
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fn unshare<'a, A: 'a + Send + Sync + Clone>(sa: Self::SharedAny<'a, A>) -> Self::FAny<'a, A>
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where
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Self: 'a,
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{
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sa
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}
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}
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};
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proc_macro::TokenStream::from(expanded)
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}
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fn add_clone_bounds(mut generics: Generics) -> Generics {
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for param in &mut generics.params {
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if let GenericParam::Type(ref mut type_param) = *param {
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type_param.bounds.push(parse_quote!(Clone));
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}
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}
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generics
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}
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