introduce workspace

crates/macros/src/action.rs

@@ -0,0 +1,79 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::DeriveInput;
+use syn::__private::TokenStream2;
+
+pub fn action(input: TokenStream) -> TokenStream {
+    let input = syn::parse::<DeriveInput>(input).unwrap();
+
+    let name = &input.ident;
+
+    let enum_data = if let syn::Data::Enum(enum_data) = &input.data {
+        enum_data
+    } else {
+        panic!("`Register` can only be used on enums");
+    };
+
+    let variant_description = generate_variant_description(enum_data);
+    let variant_constants = generate_variant_constants(name, enum_data);
+
+    let expanded = compile_output(name, variant_description, variant_constants);
+
+    TokenStream::from(expanded)
+}
+
+fn generate_variant_description(
+    enum_data: &syn::DataEnum,
+) -> impl Iterator<Item = TokenStream2> + '_ {
+    let variant_matches_backend = enum_data.variants.iter().map(|variant| {
+        let variant_name = &variant.ident;
+        let variant_lowercase =
+            proc_macro2::Literal::string(&variant_name.to_string().to_lowercase());
+        quote! {
+            Self::#variant_name => #variant_lowercase,
+        }
+    });
+    variant_matches_backend
+}
+
+fn generate_variant_constants<'a>(
+    name: &'a syn::Ident,
+    enum_data: &'a syn::DataEnum,
+) -> impl Iterator<Item = TokenStream2> + 'a {
+    let result = enum_data.variants.iter().map(move |variant| {
+        let variant_name = &variant.ident;
+
+        let variant_uppercase = proc_macro2::Ident::new(
+            &variant_name.to_string().to_uppercase(),
+            proc_macro2::Span::call_site(),
+        );
+
+        quote! {
+            pub(crate) const #variant_uppercase: &str = #name::#variant_name.name();
+        }
+    });
+    result
+}
+
+fn compile_output<T, U>(
+    name: &syn::Ident,
+    variant_description: T,
+    variant_constants: U,
+) -> TokenStream2
+where
+    T: Iterator<Item = TokenStream2>,
+    U: Iterator<Item = TokenStream2>,
+{
+    let expanded = quote! {
+        impl #name {
+            pub const fn name(&self) -> &'static str {
+                match self {
+                    #(#variant_description)*
+                }
+            }
+        }
+
+        #(#variant_constants)*
+    };
+    expanded
+}