| 1 | use proc_macro2::TokenStream; |
| 2 | use quote::quote; |
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| 3 | use syn::{Data, DeriveInput}; |
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| 4 | |
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| 5 | use crate::helpers::variant_props::HasStrumVariantProperties; |
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| 6 | use crate::helpers::{non_enum_error, HasTypeProperties}; |
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| 7 | |
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| 8 | pub(crate) fn enum_count_inner(ast: &DeriveInput) -> syn::Result<TokenStream> { |
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| 9 | let n = match &ast.data { |
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| 10 | Data::Enum(v) => v.variants.iter().try_fold(0usize, |acc, v| { |
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| 11 | if v.get_variant_properties()?.disabled.is_none() { |
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| 12 | Ok::<usize, syn::Error>(acc + 1usize) |
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| 13 | } else { |
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| 14 | Ok::<usize, syn::Error>(acc) |
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| 15 | } |
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| 16 | })?, |
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| 17 | _ => return Err(non_enum_error()), |
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| 18 | }; |
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| 19 | let type_properties = ast.get_type_properties()?; |
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| 20 | let strum_module_path = type_properties.crate_module_path(); |
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| 21 | |
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| 22 | // Used in the quasi-quotation below as `#name` |
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| 23 | let name = &ast.ident; |
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| 24 | |
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| 25 | // Helper is provided for handling complex generic types correctly and effortlessly |
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| 26 | let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl(); |
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| 27 | |
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| 28 | Ok(quote! { |
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| 29 | // Implementation |
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| 30 | impl #impl_generics #strum_module_path::EnumCount for #name #ty_generics #where_clause { |
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| 31 | const COUNT: usize = #n; |
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| 32 | } |
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| 33 | }) |
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| 34 | } |
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| 35 | |
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