1 files changed, 64 insertions, 0 deletions
diff --git a/pish_derive/src/lib.rs b/pish_derive/src/lib.rs
index 3a296fc..3a2fddc 100644
--- a/pish_derive/src/lib.rs
+++ b/pish_derive/src/lib.rs
@@ -94,3 +94,67 @@ pub fn derive_cli(input: TokenStream) -> TokenStream {
 
     TokenStream::from(expanded)
 }
+
+// AI-generated
+#[proc_macro_derive(Variants)]
+pub fn derive_variants(item: TokenStream) -> TokenStream {
+    let original = item.to_string();
+
+    // ---- extract enum name ----
+    let mut tokens = original.split_whitespace();
+
+    let mut enum_name = None;
+    while let Some(t) = tokens.next() {
+        if t == "enum" {
+            enum_name = tokens.next().map(|s| s.trim_matches('{').to_string());
+            break;
+        }
+    }
+
+    let enum_name = match enum_name {
+        Some(n) => n,
+        None => return r#"compile_error!("expected enum")"#.parse().unwrap(),
+    };
+
+    // ---- extract body between braces ----
+    let start = original.find('{').expect("missing '{'");
+    let end = original.rfind('}').expect("missing '}'");
+    let body = &original[start + 1..end];
+
+    // ---- parse variants ----
+    let mut variants = Vec::new();
+
+    for part in body.split(',') {
+        let v = part.trim();
+        if v.is_empty() {
+            continue;
+        }
+
+        // take first token as variant name
+        let name = v.split_whitespace().next().unwrap_or("").trim();
+
+        if name.is_empty() {
+            continue;
+        }
+
+        // reject non-unit variants
+        if v.contains('(') || v.contains('{') || v.contains('=') {
+            return r#"compile_error!("only unit variants supported")"#.parse().unwrap();
+        }
+
+        variants.push(format!("{}::{}", enum_name, name));
+    }
+
+    let variants_joined = variants.join(", ");
+
+    let expanded = format!(
+        "
+impl crate::variants::Variants for {enum_name} {{
+    const VARIANTS: &'static [Self] = &[
+        {variants_joined}
+    ];
+}}"
+    );
+
+    expanded.parse().unwrap()
+}