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