Replace an enable_if with an if constexpr

swift-project · Jan 3, 2022 · 8f11e42 · 8f11e42
1 parent 8f0271a
commit 8f11e42
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Showing 2 changed files with 21 additions and 26 deletions.
diff --git a/src/blackmisc/memotable.h b/src/blackmisc/memotable.h
@@ -56,13 +56,13 @@ namespace BlackMisc
         class CMemoizer : private CMemoTable<Ts>...
         {
         public:
-            //! If T is in Ts, return the index of member in the memo table.
-            template <typename T, std::enable_if_t<TIsOneOf<T, Ts...>::value, int> = 0>
-            int maybeMemoize(const T &member) { return this->CMemoTable<T>::getIndex(member); }
-
-            //! If T is not in Ts, return member.
-            template <typename T, std::enable_if_t<! TIsOneOf<T, Ts...>::value, int> = 0>
-            const T &maybeMemoize(const T &member) { return member; }
+            //! If T is in Ts, return the index of member in the memo table. Otherwise, return member.
+            template <typename T>
+            decltype(auto) maybeMemoize(const T &member)
+            {
+                if constexpr ((std::is_same_v<T, Ts> || ...)) { return this->CMemoTable<T>::getIndex(member); }
+                else { return std::as_const(member); }
+            }
 
             //! Return the values in the T table as a flat list.
             template <typename T>
@@ -78,23 +78,24 @@ namespace BlackMisc
             CSequence<T> &getTable() { return *this; }
 
             //! If T is in Ts, return proxy that will assign to member through the value at the given index in the flat list.
-            template <typename T, std::enable_if_t<TIsOneOf<T, Ts...>::value, int> = 0>
+            //! Otherwise, return member as std::reference_wrapper.
+            template <typename T>
             auto maybeUnmemoize(T &member) const
             {
-                struct Memo // clazy:exclude=rule-of-three
+                if constexpr ((std::is_same_v<T, Ts> || ...))
                 {
-                    int index;
-                    T &member;
-                    const CSequence<T> &list;
-                    int &get() { return index; }
-                    ~Memo() { if (index >= 0) { member = list[index]; } }
-                };
-                return Memo { -1, member, static_cast<const CSequence<T> &>(*this) };
+                    struct Memo // clazy:exclude=rule-of-three
+                    {
+                        int index;
+                        T &member;
+                        const CSequence<T> &list;
+                        int &get() { return index; }
+                        ~Memo() { if (index >= 0) { member = list[index]; } }
+                    };
+                    return Memo { -1, member, static_cast<const CSequence<T> &>(*this) };
+                }
+                else { return std::ref(member); }
             }
-
-            //! If T is not in Ts, return member as std::reference_wrapper.
-            template <typename T, std::enable_if_t<! TIsOneOf<T, Ts...>::value, int> = 0>
-            auto maybeUnmemoize(T &member) const { return std::ref(member); }
         };
     };
 }

diff --git a/src/blackmisc/typetraits.h b/src/blackmisc/typetraits.h
@@ -154,12 +154,6 @@ namespace BlackMisc
                                                   std::declval<T &>().unmarshallFromDbus(std::declval<const QDBusArgument &>()))>> : public std::true_type {};
     //! \endcond
 
-    /*!
-     * Trait that detects if a type is a member of a parameter pack.
-     */
-    template <typename T, typename... Ts>
-    struct TIsOneOf : public std::disjunction<std::is_same<T, Ts>...> {};
-
     /*!
      * Trait that detects if a type is QPrivateSignal.
      */