Element refinement passing on ui2

crates/gpui2_macros/src/derive_element.rs

@@ -1,75 +0,0 @@
-use proc_macro::TokenStream;
-use quote::quote;
-use syn::{parse_macro_input, DeriveInput, GenericParam};
-
-pub fn derive_element(input: TokenStream) -> TokenStream {
-    let ast = parse_macro_input!(input as DeriveInput);
-    let type_name = ast.ident;
-
-    let mut view_state_ty = quote! { V };
-
-    for param in &ast.generics.params {
-        if let GenericParam::Type(type_param) = param {
-            let type_ident = &type_param.ident;
-            view_state_ty = quote! {#type_ident};
-            break;
-        }
-    }
-
-    let attrs = &ast.attrs;
-    for attr in attrs {
-        if attr.path.is_ident("element") {
-            match attr.parse_meta() {
-                Ok(syn::Meta::List(i)) => {
-                    for nested_meta in i.nested {
-                        if let syn::NestedMeta::Meta(syn::Meta::NameValue(nv)) = nested_meta {
-                            if nv.path.is_ident("view_state") {
-                                if let syn::Lit::Str(lit_str) = nv.lit {
-                                    view_state_ty = lit_str.value().parse().unwrap();
-                                }
-                            }
-                        }
-                    }
-                }
-                _ => (),
-            }
-        }
-    }
-
-    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
-
-    let gen = quote! {
-        impl #impl_generics gpui::Element<#view_state_ty> for #type_name #ty_generics
-        #where_clause
-        {
-            type State = Option<gpui::AnyElement<#view_state_ty>>;
-
-            fn element_id(&self) -> Option<gpui::ElementId> {
-                None
-            }
-
-            fn layout(
-                &mut self,
-                view_state: &mut #view_state_ty,
-                _element_state: Option<Self::State>,
-                cx: &mut gpui::ViewContext<#view_state_ty>,
-            ) -> (gpui::LayoutId, Self::State) {
-                let mut element = self.render(view_state, cx).into_any();
-                let layout_id = element.layout(view_state, cx);
-                (layout_id, Some(element))
-            }
-
-            fn paint(
-                self,
-                _bounds: gpui::Bounds<gpui::Pixels>,
-                view_state: &mut #view_state_ty,
-                rendered_element: &mut Self::State,
-                cx: &mut gpui::ViewContext<#view_state_ty>,
-            ) {
-                rendered_element.take().unwrap().paint(view_state, cx)
-            }
-        }
-    };
-
-    gen.into()
-}

crates/gpui2_macros/src/derive_render_once.rs

@@ -0,0 +1,64 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, parse_quote, DeriveInput};
+
+pub fn derive_render_once(input: TokenStream) -> TokenStream {
+    let ast = parse_macro_input!(input as DeriveInput);
+    let type_name = &ast.ident;
+
+    let mut trait_generics = ast.generics.clone();
+    let view_type = if let Some(view_type) = specified_view_type(&ast) {
+        quote! { #view_type }
+    } else {
+        if let Some(first_type_param) = ast.generics.params.iter().find_map(|param| {
+            if let syn::GenericParam::Type(type_param) = param {
+                Some(type_param.ident.clone())
+            } else {
+                None
+            }
+        }) {
+            quote! { #first_type_param }
+        } else {
+            trait_generics.params.push(parse_quote! { V: 'static });
+            quote! { V }
+        }
+    };
+
+    let (impl_generics, _, where_clause) = trait_generics.split_for_impl();
+    let (_, type_generics, _) = ast.generics.split_for_impl();
+
+    let gen = quote! {
+        impl #impl_generics gpui::RenderOnce<#view_type> for #type_name #type_generics
+        #where_clause
+        {
+            type Element = gpui::CompositeElement<#view_type, Self>;
+
+            fn render_once(self) -> Self::Element {
+                gpui::CompositeElement::new(self)
+            }
+        }
+    };
+
+    if type_name == "Avatar" {
+        println!("{gen}");
+    }
+
+    gen.into()
+}
+
+fn specified_view_type(ast: &DeriveInput) -> Option<proc_macro2::Ident> {
+    ast.attrs.iter().find_map(|attr| {
+        if attr.path.is_ident("view") {
+            if let Ok(syn::Meta::NameValue(meta_name_value)) = attr.parse_meta() {
+                if let syn::Lit::Str(lit_str) = meta_name_value.lit {
+                    return Some(
+                        lit_str
+                            .parse::<syn::Ident>()
+                            .expect("Failed to parse view_type"),
+                    );
+                }
+            }
+        }
+        None
+    })
+}

crates/gpui2_macros/src/gpui2_macros.rs

@@ -1,6 +1,6 @@
 mod action;
 mod derive_component;
-mod derive_element;
+mod derive_render_once;
 mod register_action;
 mod style_helpers;
 mod test;
@@ -22,9 +22,9 @@ pub fn derive_component(input: TokenStream) -> TokenStream {
     derive_component::derive_component(input)
 }
 
-#[proc_macro_derive(Element, attributes(element))]
-pub fn derive_element(input: TokenStream) -> TokenStream {
-    derive_element::derive_element(input)
+#[proc_macro_derive(RenderOnce, attributes(view))]
+pub fn derive_render_once(input: TokenStream) -> TokenStream {
+    derive_render_once::derive_render_once(input)
 }
 
 #[proc_macro]