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use proc_macro::{TokenStream, TokenTree};
use proc_macro2::Span;
use quote::quote;
use syn::Ident;
pub(crate) fn declare_output_enum(input: TokenStream) -> TokenStream {
let branches = match input.into_iter().next() {
Some(TokenTree::Group(group)) => group.stream().into_iter().count(),
_ => panic!("unexpected macro input"),
};
let variants = (0..branches)
.map(|num| Ident::new(&format!("_{}", num), Span::call_site()))
.collect::<Vec<_>>();
let mask = Ident::new(
if branches <= 8 {
"u8"
} else if branches <= 16 {
"u16"
} else if branches <= 32 {
"u32"
} else if branches <= 64 {
"u64"
} else {
panic!("up to 64 branches supported");
},
Span::call_site(),
);
TokenStream::from(quote! {
pub(super) enum Out<#( #variants ),*> {
#( #variants(#variants), )*
Disabled,
}
pub(super) type Mask = #mask;
})
}