From 6d5c2da0306a6df736305efbe87cc84fcd2b2cb0 Mon Sep 17 00:00:00 2001
From: Dreaded_X <tim@huizinga.dev>
Date: Mon, 15 Sep 2025 21:32:57 +0200
Subject: [PATCH] feat: Added support for flatten

---
 lua_typed_macro/src/lib.rs | 21 ++++++++++++++++-----
 tests/flatten.rs           | 24 ++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 5 deletions(-)
 create mode 100644 tests/flatten.rs

diff --git a/lua_typed_macro/src/lib.rs b/lua_typed_macro/src/lib.rs
index e22d671..1d2b28e 100644
--- a/lua_typed_macro/src/lib.rs
+++ b/lua_typed_macro/src/lib.rs
@@ -11,6 +11,7 @@ struct StructField {
     ty: syn::Type,
     case: Option<Case<'static>>,
     default: bool,
+    flatten: bool,
 }
 
 impl ToTokens for StructField {
@@ -23,13 +24,19 @@ impl ToTokens for StructField {
 
         let ty = &self.ty;
 
-        let default = if self.default { "?" } else { "" };
+        if self.flatten {
+            tokens.extend(quote! {
+                <#ty as Typed>::generate_members().unwrap_or("".to_string())
+            });
+        } else {
+            let default = if self.default { "?" } else { "" };
 
-        let format = format!("---@field {} {{}}{}\n", name, default);
+            let format = format!("---@field {} {{}}{}\n", name, default);
 
-        tokens.extend(quote! {
-            format!(#format, <#ty as Typed>::type_name())
-        });
+            tokens.extend(quote! {
+                format!(#format, <#ty as Typed>::type_name())
+            });
+        }
     }
 }
 
@@ -168,6 +175,7 @@ pub fn typed(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
             let mut fields = Vec::new();
             for field in data_struct.fields {
                 let mut default = false;
+                let mut flatten = false;
                 for attr in &field.attrs {
                     if attr.path().is_ident("serde")
                         && let Err(err) = attr.parse_nested_meta(|meta| {
@@ -177,6 +185,8 @@ pub fn typed(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
                                     meta.input.parse::<Token![=]>()?;
                                     meta.input.parse::<LitStr>()?;
                                 }
+                            } else if meta.path.is_ident("flatten") {
+                                flatten = true;
                             }
 
                             Ok(())
@@ -191,6 +201,7 @@ pub fn typed(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
                     ty: field.ty,
                     case,
                     default,
+                    flatten,
                 });
             }
 
diff --git a/tests/flatten.rs b/tests/flatten.rs
new file mode 100644
index 0000000..f3b2c97
--- /dev/null
+++ b/tests/flatten.rs
@@ -0,0 +1,24 @@
+use lua_typed::Typed;
+
+#[derive(Typed)]
+pub struct B {
+    pub hello: String,
+    pub world: bool,
+}
+
+#[derive(Typed)]
+pub struct A {
+    #[serde(flatten)]
+    pub b: B,
+    pub cool: u32,
+}
+
+#[test]
+fn flatten() {
+    insta::assert_snapshot!(<A as Typed>::generate_full().unwrap(), @r"
+    ---@class A
+    ---@field hello string
+    ---@field world boolean
+    ---@field cool integer
+    ");
+}