wip: fix dsl

proc/src/proc_view.rs

@@ -39,26 +39,22 @@ impl Parse for ViewImpl {
 
 impl ToTokens for ViewDef {
     fn to_tokens (&self, out: &mut TokenStream2) {
-        let Self(ViewMeta { output }, ViewImpl { block, exposed }) = self;
-        let self_ty = &block.self_ty;
-        // Expressions are handled by built-in functions
-        // that operate over constants and symbols.
-        let builtin = builtins_with_boxes_output(quote! { #output }).map(|builtin|quote! {
-            ::tengri::dsl::DslVal::Exp(_, expr) => return Ok(Some(
-                #builtin::dsl_from(self, expr, ||Box::new("failed to load builtin".into()))?
-                    .boxed()
-            )),
-        });
-        // Symbols are handled by user-taked functions
-        // that take no parameters but `&self`.
-        let exposed = exposed.iter().map(|(key, value)|write_quote(quote! {
-            ::tengri::dsl::DslVal::Sym(#key) => return Ok(Some(
-                self.#value().boxed()
-            )),
-        }));
+        let Self(_, ViewImpl { block, .. }) = self;
+        let generated = self.generated();
         write_quote_to(out, quote! {
-            // Original user-taked implementation:
             #block
+            #generated
+        })
+    }
+}
+
+impl ViewDef {
+    fn generated (&self) -> impl ToTokens {
+        let Self(ViewMeta { output }, ViewImpl { block, exposed }) = self;
+        let self_ty  = &block.self_ty;
+        let builtins = self.builtins();
+        let exposed  = self.exposed();
+        quote! {
             /// Generated by [tengri_proc].
             ///
             /// Makes [#self_ty] able to construct the [Render]able
@@ -70,11 +66,30 @@ impl ToTokens for ViewDef {
                 fn try_dsl_into (&self, dsl: &impl ::tengri::dsl::Dsl)
                     -> Perhaps<Box<dyn ::tengri::output::Render<#output> + 'state>>
                 {
-                    use ::tengri::dsl::DslVal::*;
-                    Ok(match dsl.val() { #(#builtin)* #(#exposed)* _ => return Ok(None) })
+                    Ok(match dsl.val() { #builtins #exposed _ => return Ok(None) })
                 }
             }
-        })
+        }
+    }
+    /// Expressions are handled by built-in functions
+    /// that operate over constants and symbols.
+    fn builtins (&self) -> impl ToTokens {
+        let Self(ViewMeta { output }, ViewImpl { block, exposed }) = self;
+        let builtins = builtins_with_boxes_output(quote! { #output }).map(|builtin|quote! {
+            ::tengri::dsl::DslVal::Exp(_, expr) => return Ok(Some(
+                #builtin::from_dsl(self, expr, ||Box::new("failed to load builtin".into()))?
+                    .boxed()
+            )),
+        });
+        quote! { #(#builtins)* }
+    }
+    /// Symbols are handled by user-taked functions that take no parameters but `&self`.
+    fn exposed (&self) -> impl ToTokens {
+        let Self(ViewMeta { output }, ViewImpl { block, exposed }) = self;
+        let exposed = exposed.iter().map(|(key, value)|write_quote(quote! {
+            #key => return Ok(Some(self.#value().boxed())),
+        }));
+        quote! { ::tengri::dsl::DslVal::Sym(key) => match key.as_ref() { #(#exposed)* } }
     }
 }