use inflector::Inflector;
use quote::format_ident;
pub fn derive(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input: syn::DeriveInput = match syn::parse(item) {
Ok(input) => input,
Err(e) => return e.into_compile_error().into(),
};
let syn::DeriveInput { generics, data, .. } = input;
match data {
syn::Data::Enum(syn::DataEnum { variants, .. }) => {
let methods = variants.into_iter().map(|syn::Variant { ident, fields, .. }| {
let snake_cased_ident = format_ident!("{}", ident.to_string().to_snake_case());
let ref_fields =
fields.into_iter().enumerate().map(|(idx, syn::Field { ident, ty, .. })| {
let field_name = ident.unwrap_or_else(|| format_ident!("_{}", idx));
let field_ty = match ty {
syn::Type::Reference(r) => {
quote::quote!(#r)
},
t => {
quote::quote!(&#t)
},
};
quote::quote!(#field_name: #field_ty,)
});
quote::quote!(fn #snake_cased_ident( #(#ref_fields)* ) -> Weight;)
});
let res = quote::quote! {
pub trait XcmWeightInfo #generics {
#(#methods)*
}
};
res.into()
},
syn::Data::Struct(syn::DataStruct { struct_token, .. }) => {
let msg = "structs are not supported by 'derive(XcmWeightInfo)'";
syn::Error::new(struct_token.span, msg).into_compile_error().into()
},
syn::Data::Union(syn::DataUnion { union_token, .. }) => {
let msg = "unions are not supported by 'derive(XcmWeightInfo)'";
syn::Error::new(union_token.span, msg).into_compile_error().into()
},
}
}