better global state structure?

macro/src/lib.rs

@@ -2,10 +2,11 @@ extern crate proc_macro;
 use proc_macro::TokenStream;
 use quote::quote;
 use syn::{
-    Attribute, Block, Error, GenericParam, Generics, Ident, ItemTrait, Signature, Token,
-    Visibility,
+    Attribute, Block, Error, Fields, FieldsNamed, GenericParam, Generics, Ident, ItemStruct,
+    ItemTrait, Meta, Signature, Token, Visibility,
     parse::{Parse, ParseStream, Result},
     parse_macro_input, parse_quote,
+    spanned::Spanned,
 };
 
 struct Input {
@@ -94,3 +95,86 @@ pub fn widget_trait(input: TokenStream) -> TokenStream {
     }
     .into()
 }
+
+#[proc_macro_derive(UiState, attributes(rsc))]
+pub fn derive_ui_state(input: TokenStream) -> TokenStream {
+    let mut output = proc_macro2::TokenStream::new();
+
+    let state: ItemStruct = parse_macro_input!(input);
+    let sname = state.ident;
+    let rscname = Ident::new(&(sname.to_string() + "Rsc"), sname.span());
+    let mut rsc_fields = Vec::new();
+
+    for field in state.fields {
+        let Some(attr) = field.attrs.iter().find(|a| a.path().is_ident("rsc")) else {
+            continue;
+        };
+        let Meta::List(list) = &attr.meta else {
+            output.extend(Error::new(attr.span(), "invalid attr syntax").into_compile_error());
+            continue;
+        };
+        let tname: Ident = match list.parse_args::<Ident>() {
+            Ok(ident) => ident,
+            Err(err) => {
+                output.extend(err.to_compile_error());
+                continue;
+            }
+        };
+        let fty = &field.ty;
+        let fname = &field.ident.unwrap();
+        rsc_fields.extend(quote! {#fname: #fty,});
+        output.extend(quote! {
+            impl #tname for #sname {
+                fn get(&self) -> &#fty {
+                    &self.#fname
+                }
+                fn get_mut(&mut self) -> &mut #fty {
+                    &mut self.#fname
+                }
+            }
+            impl #tname for #rscname {
+                fn get(&self) -> &#fty {
+                    &self.#fname
+                }
+                fn get_mut(&mut self) -> &mut #fty {
+                    &mut self.#fname
+                }
+            }
+        });
+    }
+    let vis = state.vis;
+    output.extend(quote! {
+        #vis struct #rscname {
+            #(#rsc_fields)*
+        }
+
+        impl HasState for #sname {
+            type State = #sname;
+        }
+
+        impl HasState for #rscname {
+            type State = #sname;
+        }
+    });
+    output.into()
+}
+
+#[proc_macro_attribute]
+pub fn default_ui_state(_attr: TokenStream, input: TokenStream) -> TokenStream {
+    let mut state: ItemStruct = parse_macro_input!(input);
+    let Fields::Named(fields) = &mut state.fields else {
+        panic!("must be on named fields struct");
+    };
+    let name = &state.ident;
+    state.attrs.push(parse_quote! {#[derive(UiState)]});
+    let new: FieldsNamed = parse_quote! {{
+        #[rsc(HasUi)]
+        pub ui: Ui,
+        #[rsc(HasDefaultUiState)]
+        pub ui_state: DefaultUiState,
+        #[rsc(HasEvents)]
+        pub events: iris::prelude::EventManager<#name>,
+    }};
+    fields.named.extend(new.named);
+    quote! {#state}.into()
+}