Added Block trait

Author: ZhukMax

efx/src/tags/column.rs

@@ -4,15 +4,15 @@ use quote::{ToTokens, quote};
 
 use crate::render::render_nodes_as_stmts;
 use crate::tags::util::{attr_map, f32_opt};
-use crate::tags::{Tag, TagAttributes};
+use crate::tags::{Block, Tag, TagAttributes};
 use efx_attrnames::AttrNames;
 
 pub struct Column {
     attributes: Attributes,
     element: Element,
 }
 
-impl Tag for Column {
+impl Block for Column {
     fn from_element(el: &Element) -> Result<Self, TokenStream> {
         let attributes = Attributes::new(el)?;
         Ok(Self {
@@ -51,19 +51,6 @@ impl Tag for Column {
         }
     }
 
-    /// Full render: prologue → content → epilogue.
-    fn render<UI: ToTokens>(&self, ui: &UI) -> TokenStream {
-        let (prolog, epilogue) = self.prolog_epilogue(ui);
-        let content = self.content(ui);
-        quote! {{
-            #prolog
-            #content
-            #epilogue
-        }}
-    }
-}
-
-impl Column {
     fn prolog_epilogue<UI: ToTokens>(&self, ui: &UI) -> (TokenStream, TokenStream) {
         let mut prolog = TokenStream::new();
         let mut epilogue = TokenStream::new();

efx/src/tags/mod.rs

@@ -17,7 +17,7 @@ use efx_core::Element;
 pub use hyperlink::Hyperlink;
 pub use label::render_label_stmt;
 use proc_macro2::TokenStream;
-use quote::ToTokens;
+use quote::{quote, ToTokens};
 pub use row::Row;
 pub use scroll_area::render_scroll_area_stmt;
 pub use separator::Separator;
@@ -38,6 +38,36 @@ pub trait Tag: Sized {
     fn render<UI: ToTokens>(&self, ui: &UI) -> TokenStream;
 }
 
+pub trait Block: Sized {
+    fn from_element(el: &Element) -> Result<Self, TokenStream>
+    where
+        Self: Sized;
+    /// Render contents
+    fn content<UI: ToTokens>(&self, ui: &UI) -> TokenStream;
+    fn prolog_epilogue<UI: ToTokens>(&self, ui: &UI) -> (TokenStream, TokenStream);
+
+    /// Full render: prologue → content → epilogue.
+    fn render<UI: ToTokens>(&self, ui: &UI) -> TokenStream {
+        let (prolog, epilogue) = self.prolog_epilogue(ui);
+        let content = self.content(ui);
+        quote! {{ #prolog #content #epilogue }}
+    }
+}
+
+impl<T: Block> Tag for T {
+    fn from_element(el: &Element) -> Result<Self, TokenStream> {
+        <T as Block>::from_element(el)
+    }
+
+    fn content<UI: ToTokens>(&self, ui: &UI) -> TokenStream {
+        <T as Block>::content(self, ui)
+    }
+
+    fn render<UI: ToTokens>(&self, ui: &UI) -> TokenStream {
+        <T as Block>::render(self, ui)
+    }
+}
+
 pub(crate) trait TagAttributes {
     fn new(el: &Element) -> Result<Self, TokenStream>
     where

efx/src/tags/row.rs

@@ -4,14 +4,14 @@ use quote::{ToTokens, quote};
 use efx_attrnames::AttrNames;
 use crate::render::render_nodes_as_stmts;
 use crate::tags::util::{attr_map, bool_or, f32_opt};
-use crate::tags::{Tag, TagAttributes};
+use crate::tags::{Block, Tag, TagAttributes};
 
 pub struct Row {
     attributes: Attributes,
     element: Element,
 }
 
-impl Tag for Row {
+impl Block for Row {
     fn from_element(el: &Element) -> Result<Self, TokenStream> {
         let attributes = Attributes::new(el)?;
         Ok(Self {
@@ -58,20 +58,11 @@ impl Tag for Row {
         }
     }
 
-    /// Full render: prologue → content → epilogue.
-    fn render<UI: ToTokens>(&self, ui: &UI) -> TokenStream {
-        let (prolog, epilogue) = self.prolog_epilogue(ui);
-        let content = self.content(ui);
-        quote! {{ #prolog #content #epilogue }}
-    }
-}
-
-impl Row {
     fn prolog_epilogue<UI: ToTokens>(&self, ui: &UI) -> (TokenStream, TokenStream) {
         let mut prolog = TokenStream::new();
         let mut epilogue = TokenStream::new();
 
-        if let Some(n) = self.attributes.gap {
+        if let Some(n) = &self.attributes.gap {
             prolog.extend(quote! {
                 let __efx_old_gap_x = #ui.spacing().item_spacing.x;
                 #ui.spacing_mut().item_spacing.x = #n as _;