use Option<ENUM> instead of Variant

Author: burrbull

CHANGELOG.md

@@ -28,6 +28,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 
+- [breaking-change] remove `Variant<U, ENUM_A>`, use `Option<ENUM_A>` instead
+
 - split out register size type (`RawType`) from `ResetValue` trait
 
 - `anyhow` crate is used for error handling

src/generate/generic.rs

@@ -223,15 +223,6 @@ impl<REG: RegisterSpec> W<REG> {
     }
 }
 
-/// Used if enumerated values cover not the whole range.
-#[derive(Clone, Copy, PartialEq)]
-pub enum Variant<U, T> {
-    /// Expected variant.
-    Val(T),
-    /// Raw bits.
-    Res(U),
-}
-
 /// Field reader.
 ///
 /// Result of the `read` methods of fields.

src/generate/register.rs

@@ -451,7 +451,7 @@ pub fn fields(
                             let pc = &v.pc;
 
                             if has_reserved_variant {
-                                quote! { #i => Val(#name_pc_a::#pc), }
+                                quote! { #i => Some(#name_pc_a::#pc), }
                             } else {
                                 quote! { #i => #name_pc_a::#pc, }
                             }
@@ -461,7 +461,7 @@ pub fn fields(
 
                         if has_reserved_variant {
                             arms.extend(quote! {
-                                i => Res(i),
+                                _ => None,
                             });
                         } else if 1 << width.to_ty_width()? != variants.len() {
                             arms.extend(quote! {
@@ -473,8 +473,7 @@ pub fn fields(
                             enum_items.extend(quote! {
                                 ///Get enumerated values variant
                                 #inline
-                                pub fn variant(&self) -> crate::Variant<#fty, #name_pc_a> {
-                                    use crate::Variant::*;
+                                pub fn variant(&self) -> Option<#name_pc_a> {
                                     match self.bits {
                                         #arms
                                     }