feat: app state derive macro (#180)

crates/macros/src/common/mod.rs

@@ -5,3 +5,4 @@ pub mod inject;
 pub mod injectable;
 pub mod route;
 pub mod routes;
+pub mod state;

crates/macros/src/common/state.rs

@@ -0,0 +1,19 @@
+use proc_macro::TokenStream;
+
+pub(crate) fn derive_app_state_macro(input: TokenStream) -> TokenStream {
+    let input = syn::parse_macro_input!(input as syn::ItemStruct);
+    let name = &input.ident;
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
+    let expanded = quote::quote! {
+        impl shared::server::context::AppState for #name #impl_generics #ty_generics #where_clause {
+            fn as_any(&self) -> &dyn std::any::Any {
+                self
+            }
+            fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
+                self
+            }
+        }
+    };
+    TokenStream::from(expanded)
+}

crates/macros/src/lib.rs

@@ -387,3 +387,17 @@ pub fn query_derive_macro(input: TokenStream) -> TokenStream {
 pub fn param_derive_macro(input: TokenStream) -> TokenStream {
     param_macro(input)
 }
+
+#[proc_macro_derive(AppState)]
+/// The `AppState` derive macro is used to derive a struct that can be used as a state in a server.
+///
+/// ### Example
+/// ```rust ignore
+/// #[derive(AppState)]
+/// struct MyState {
+///    // fields
+/// }
+/// ```
+pub fn app_state_derive_macro(input: TokenStream) -> TokenStream {
+    common::state::derive_app_state_macro(input)
+}