feat(util-macros): add VariantArr derive macro

1 files changed, 50 insertions, 1 deletions

diff --git a/util-macros/src/lib.rs b/util-macros/src/lib.rs
index 83b5f58..654c626 100644
--- a/util-macros/src/lib.rs
+++ b/util-macros/src/lib.rs
@@ -1,6 +1,6 @@
 use proc_macro::{TokenStream, TokenTree};
 use quote::quote;
-use syn::{parse, Ident, ItemEnum};
+use syn::{parse, Ident, ItemEnum, Token};
 
 /// Subtracts two numbers and calls a given callback macro with the result. Optionally, a
 /// additional argument (delimeted) can be given which will also be passed to the
@@ -199,3 +199,52 @@ pub fn from_repr(input: TokenStream) -> TokenStream
     }
     .into()
 }
+
+#[proc_macro_derive(VariantArr, attributes(variant_arr))]
+pub fn variant_arr(input: TokenStream) -> TokenStream
+{
+    let enum_item = parse::<ItemEnum>(input).unwrap();
+
+    let arr_ident_attr = enum_item
+        .attrs
+        .iter()
+        .find(|attr| {
+            attr.path()
+                .get_ident()
+                .is_some_and(|attr_ident| attr_ident == "variant_arr")
+        })
+        .expect("No variant_arr attribute found");
+
+    let mut arr_name = None;
+
+    arr_ident_attr
+        .parse_nested_meta(|meta| {
+            if meta.path.is_ident("name") {
+                meta.input.parse::<Token![=]>()?;
+
+                arr_name = Some(meta.input.parse::<Ident>()?);
+
+                return Ok(());
+            }
+
+            Err(meta.error("Unknown field in variant_arr attribute"))
+        })
+        .unwrap();
+
+    let arr_name = arr_name.expect("Missing field 'name' in variant_arr attribute");
+
+    let variants = enum_item
+        .variants
+        .iter()
+        .map(|variant| variant.ident.clone());
+
+    let enum_ident = enum_item.ident.clone();
+
+    quote! {
+        impl #enum_ident
+        {
+            pub const #arr_name: &[Self] = &[#(Self::#variants,)*];
+        }
+    }
+    .into()
+}