refactor: make it simple.

tasks/ast_codegen/src/generators/derive_clone_in.rs

@@ -51,7 +51,7 @@ impl Generator for DeriveCloneIn {
 
 fn derive_enum(def: &EnumDef) -> TokenStream {
     let ty_ident = def.ident();
-    impl_clone_in(&ty_ident, def.has_lifetime, || {
+    let (alloc, body) = {
         let mut used_alloc = false;
         let matches = def
             .all_variants()
@@ -74,12 +74,13 @@ fn derive_enum(def: &EnumDef) -> TokenStream {
                 }
             },
         )
-    })
+    };
+    impl_clone_in(&ty_ident, def.has_lifetime, alloc, body)
 }
 
 fn derive_struct(def: &StructDef) -> TokenStream {
     let ty_ident = def.ident();
-    impl_clone_in(&ty_ident, def.has_lifetime, || {
+    let (alloc, body) = {
         let (alloc_ident, body) = if def.fields.is_empty() {
             (format_ident!("_"), TokenStream::default())
         } else {
@@ -89,45 +90,33 @@ fn derive_struct(def: &StructDef) -> TokenStream {
             });
             (format_ident!("alloc"), quote!({ #(#fields),* }))
         };
-        (
-            alloc_ident,
-            quote! {
-                    #ty_ident #body
-            },
-        )
-    })
+        (alloc_ident, quote!( #ty_ident #body ))
+    };
+    impl_clone_in(&ty_ident, def.has_lifetime, alloc, body)
 }
 
-fn impl_clone_in<F>(ty_ident: &Ident, has_lifetime: bool, body: F) -> TokenStream
-where
-    F: FnOnce() -> (/* allocator name */ Ident, TokenStream),
-{
-    let (alloc, body) = body();
-    let (impl_lifetimes, trait_lifetime, old_lifetime, new_lifetime, alloc_ref) = if has_lifetime {
-        (
-            quote!(<'old_alloc, 'new_alloc>),
-            quote!(<'new_alloc>),
-            quote!(<'old_alloc>),
-            quote!(<'new_alloc>),
-            quote!(&'new_alloc),
-        )
+fn impl_clone_in(
+    ty_ident: &Ident,
+    has_lifetime: bool,
+    alloc: Ident,
+    body: TokenStream,
+) -> TokenStream {
+    if has_lifetime {
+        quote! {
+            impl <'old_alloc, 'new_alloc> CloneIn<'new_alloc> for #ty_ident<'old_alloc> {
+                type Cloned = #ty_ident<'new_alloc>;
+                fn clone_in(&self, #alloc: &'new_alloc Allocator) -> Self::Cloned {
+                    #body
+                }
+            }
+        }
     } else {
-        (
-            quote!(<'alloc>),
-            quote!(<'alloc>),
-            TokenStream::default(),
-            TokenStream::default(),
-            quote!(&'alloc),
-        )
-    };
-
-    quote! {
-        endl!();
-        impl #impl_lifetimes CloneIn #trait_lifetime for #ty_ident #old_lifetime {
-            type Cloned = #ty_ident #new_lifetime;
-
-            fn clone_in(&self, #alloc: #alloc_ref Allocator) -> Self::Cloned {
-                #body
+        quote! {
+            impl <'alloc> CloneIn<'alloc> for #ty_ident {
+                type Cloned = #ty_ident;
+                fn clone_in(&self, #alloc: &'alloc Allocator) -> Self::Cloned {
+                    #body
+                }
             }
         }
     }