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use proc_macro2::TokenStream;
use quote::quote;
use syn::{Data, DeriveInput};
use crate::helpers::{non_enum_error, HasTypeProperties};
pub(crate) fn enum_count_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
let n = match &ast.data {
Data::Enum(v) => v.variants.len(),
_ => return Err(non_enum_error()),
};
let type_properties = ast.get_type_properties()?;
let strum_module_path = type_properties.crate_module_path();
// Used in the quasi-quotation below as `#name`
let name = &ast.ident;
// Helper is provided for handling complex generic types correctly and effortlessly
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
Ok(quote! {
// Implementation
impl #impl_generics #strum_module_path::EnumCount for #name #ty_generics #where_clause {
const COUNT: usize = #n;
}
})
}
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