Extract variant code to its own function in style_derive::to_css

components/style_derive/to_css.rs

@@ -2,11 +2,11 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use cg;
+use cg::{self, WhereClause};
 use darling::util::Override;
 use quote::Tokens;
 use syn::{self, Ident};
-use synstructure;
+use synstructure::{Structure, VariantInfo};
 
 pub fn derive(input: syn::DeriveInput) -> Tokens {
     let name = &input.ident;
@@ -15,9 +15,50 @@ pub fn derive(input: syn::DeriveInput) -> Tokens {
         cg::trait_parts(&input, &trait_path);
 
     let input_attrs = cg::parse_input_attrs::<CssInputAttrs>(&input);
-    let s = synstructure::Structure::new(&input);
+    let s = Structure::new(&input);
 
     let match_body = s.each_variant(|variant| {
+        derive_variant_arm(variant, &mut where_clause)
+    });
+
+    let mut impls = quote! {
+        impl #impl_generics ::style_traits::ToCss for #name #ty_generics #where_clause {
+            #[allow(unused_variables)]
+            #[inline]
+            fn to_css<W>(
+                &self,
+                dest: &mut ::style_traits::CssWriter<W>,
+            ) -> ::std::fmt::Result
+            where
+                W: ::std::fmt::Write
+            {
+                match *self {
+                    #match_body
+                }
+            }
+        }
+    };
+
+    if input_attrs.derive_debug {
+        impls.append_all(quote! {
+            impl #impl_generics ::std::fmt::Debug for #name #ty_generics #where_clause {
+                fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                    ::style_traits::ToCss::to_css(
+                        self,
+                        &mut ::style_traits::CssWriter::new(f),
+                    )
+                }
+            }
+        });
+    }
+
+    impls
+}
+
+fn derive_variant_arm(
+    variant: &VariantInfo,
+    where_clause: &mut WhereClause,
+) -> Tokens {
     let bindings = variant.bindings();
     let identifier = cg::to_css_identifier(variant.ast().ident.as_ref());
     let ast = variant.ast();
@@ -91,41 +132,7 @@ pub fn derive(input: syn::DeriveInput) -> Tokens {
             ::std::fmt::Write::write_str(dest, ")")
         }
     }
-        Some(expr)
+    expr
-    });
-
-    let mut impls = quote! {
-        impl #impl_generics ::style_traits::ToCss for #name #ty_generics #where_clause {
-            #[allow(unused_variables)]
-            #[inline]
-            fn to_css<W>(
-                &self,
-                dest: &mut ::style_traits::CssWriter<W>,
-            ) -> ::std::fmt::Result
-            where
-                W: ::std::fmt::Write
-            {
-                match *self {
-                    #match_body
-                }
-            }
-        }
-    };
-
-    if input_attrs.derive_debug {
-        impls.append_all(quote! {
-            impl #impl_generics ::std::fmt::Debug for #name #ty_generics #where_clause {
-                fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
-                    ::style_traits::ToCss::to_css(
-                        self,
-                        &mut ::style_traits::CssWriter::new(f),
-                    )
-                }
-            }
-        });
-    }
-
-    impls
 }
 
 #[darling(attributes(css), default)]