enum_table_derive/
lib.rs

1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::Data;
4use syn::Result;
5use syn::{parse_macro_input, DeriveInput};
6
7#[proc_macro_derive(Enumable)]
8pub fn derive_enumable(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
9    derive_enumable_internal(parse_macro_input!(input as DeriveInput))
10        .unwrap_or_else(syn::Error::into_compile_error)
11        .into()
12}
13
14fn derive_enumable_internal(input: DeriveInput) -> Result<TokenStream> {
15    let variants = match &input.data {
16        Data::Enum(data) => &data.variants,
17        _ => {
18            return Err(syn::Error::new_spanned(
19                &input,
20                "Enumable can only be derived for enums",
21            ))
22        }
23    };
24
25    let variants = variants
26        .iter()
27        .map(|v| {
28            if !matches!(v.fields, syn::Fields::Unit) {
29                return Err(syn::Error::new_spanned(
30                    v,
31                    "Enumable can only be derived for unit variants",
32                ));
33            }
34            Ok(&v.ident)
35        })
36        .collect::<Result<Vec<_>>>()?;
37
38    let ident = &input.ident;
39    let expanded = quote! {
40        impl enum_table::Enumable for #ident {
41            const VARIANTS: &'static [#ident] = &[#(Self::#variants),*];
42        }
43    };
44
45    Ok(expanded)
46}
enum_table_derive/lib.rs

enum_table_derive/
lib.rs
