RichEnum::value_of() - return std::optional<V>

... instead of std::optional<std::reference_wrapper<const V> This also matches magic_enum::enum_cast<>()
teslamotors · Sep 17, 2024 · 1ecb8ed · 1ecb8ed
1 parent 97a9bdf
commit 1ecb8ed
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Showing 2 changed files with 20 additions and 16 deletions.
diff --git a/include/fixed_containers/enum_utils.hpp b/include/fixed_containers/enum_utils.hpp
@@ -167,8 +167,7 @@ struct RichEnumAdapter
 };
 
 template <class RichEnum>
-constexpr std::optional<std::reference_wrapper<const RichEnum>> value_of(
-    const std::string_view& name)
+constexpr std::optional<RichEnum> value_of(const std::string_view& name)
 {
     for (const RichEnum& rich_enum_val : RichEnum::values())
     {
@@ -182,8 +181,7 @@ constexpr std::optional<std::reference_wrapper<const RichEnum>> value_of(
 }
 
 template <class RichEnum>
-constexpr std::optional<std::reference_wrapper<const RichEnum>> value_of(
-    const typename RichEnum::BackingEnum& backing_enum)
+constexpr std::optional<RichEnum> value_of(const typename RichEnum::BackingEnum& backing_enum)
 {
     const auto& rich_enum_values = RichEnum::values();
 
@@ -215,7 +213,7 @@ constexpr std::optional<std::reference_wrapper<const RichEnum>> value_of(
 }
 
 template <class RichEnum>
-constexpr std::optional<std::reference_wrapper<const RichEnum>> value_of(
+constexpr std::optional<RichEnum> value_of(
     std::underlying_type_t<typename RichEnum::BackingEnum> enum_integer)
 {
     return value_of<RichEnum>(typename RichEnum::BackingEnum(enum_integer));
@@ -420,19 +418,17 @@ class SkeletalRichEnumLite
     using ValuesFriend = SkeletalRichEnumValues<RichEnumType>;
 
 public:
-    static constexpr std::optional<std::reference_wrapper<const RichEnumType>> value_of(
-        const std::string_view& name)
+    static constexpr std::optional<RichEnumType> value_of(const std::string_view& name)
     {
         return rich_enums_detail::value_of<RichEnumType>(name);
     }
 
-    static constexpr std::optional<std::reference_wrapper<const RichEnumType>> value_of(
-        const BackingEnum& backing_enum)
+    static constexpr std::optional<RichEnumType> value_of(const BackingEnum& backing_enum)
     {
         return rich_enums_detail::value_of<RichEnumType>(backing_enum);
     }
 
-    static constexpr std::optional<std::reference_wrapper<const RichEnumType>> value_of(
+    static constexpr std::optional<RichEnumType> value_of(
         std::underlying_type_t<BackingEnum> enum_integer)
     {
         return rich_enums_detail::value_of<RichEnumType>(enum_integer);

diff --git a/test/enum_utils_test.cpp b/test/enum_utils_test.cpp
@@ -296,8 +296,7 @@ TEST(RichEnum, ValueOfName)
     }
 
     {
-        constexpr const TestRichEnum1& MY_VALUE = TestRichEnum1::value_of("C_ONE").value();
-
+        constexpr TestRichEnum1 MY_VALUE = TestRichEnum1::value_of("C_ONE").value();
         static_assert(MY_VALUE == TestRichEnum1::C_ONE());
     }
 }
@@ -315,8 +314,7 @@ TEST(RichEnum, ValueOfBackingEnum)
 
     {
         using BE = detail::TestRichEnum1BackingEnum;
-        constexpr const TestRichEnum1& MY_VALUE = TestRichEnum1::value_of(BE::C_ONE).value();
-
+        constexpr TestRichEnum1 MY_VALUE = TestRichEnum1::value_of(BE::C_ONE).value();
         static_assert(MY_VALUE == TestRichEnum1::C_ONE());
     }
 }
@@ -332,12 +330,22 @@ TEST(RichEnum, ValueOfUnderlyingInt)
     }
 
     {
-        constexpr const TestRichEnum1& MY_VALUE = TestRichEnum1::value_of(19).value();
-
+        constexpr TestRichEnum1 MY_VALUE = TestRichEnum1::value_of(19).value();
         static_assert(MY_VALUE == TestRichEnum1::C_ONE());
     }
 }
 
+TEST(RichEnum, ValueOfParityWithBuiltinEnums)
+{
+    // Optional values
+    {
+        static_assert(std::same_as<std::optional<TestEnum1>,
+                                   decltype(magic_enum::enum_cast<TestEnum1>("ONE"))>);
+        static_assert(
+            std::same_as<std::optional<TestRichEnum1>, decltype(TestRichEnum1::value_of("C_ONE"))>);
+    }
+}
+
 TEST(RichEnum, UniqueValuesArrays)
 {
     constexpr const auto& ENUM1_VALUES = TestRichEnum1::values();