refactor(templates): refactor TVariant::Visit to Visit
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797386f3d6
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9cc7ac9480
@ -242,9 +242,64 @@ void TestVariant()
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}
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{
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// TVariant<bool> TempA = false;
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// TempA.Visit([](auto& A) { A = true; });
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// always_check(TempA.GetValue<bool>());
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using VariantType = TVariant<int32, int64, float64>;
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VariantType TempArray[] = { 10, 15ll, 1.5 };
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for(auto&& TempA : TempArray)
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{
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Visit(
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[](auto&& A)
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{
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using T = TRemoveCVRef<decltype(A)>;
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if constexpr (CSameAs<T, int32>) always_check(A == 10);
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else if constexpr (CSameAs<T, int64>) always_check(A == 15ll);
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else if constexpr (CSameAs<T, float64>) always_check(A == 1.5);
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else always_check_no_entry();
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},
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TempA
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);
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VariantType TempB = Visit([](auto&& A) -> VariantType { return A + A; }, TempA);
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Visit(
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[](auto&& A, auto&& B)
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{
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using T = TRemoveCVRef<decltype(A)>;
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if constexpr (CSameAs<T, int32>) always_check(A == 10 && B == 20);
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else if constexpr (CSameAs<T, int64>) always_check(A == 15ll && B == 30ll);
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else if constexpr (CSameAs<T, float64>) always_check(A == 1.5 && B == 3.0);
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else always_check_no_entry();
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},
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TempA, TempB
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);
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Visit([](auto&& A) { A *= 2; }, TempA);
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Visit(
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[](auto&& A)
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{
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using T = TRemoveCVRef<decltype(A)>;
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if constexpr (CSameAs<T, int32>) always_check(A == 20);
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else if constexpr (CSameAs<T, int64>) always_check(A == 30ll);
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else if constexpr (CSameAs<T, float64>) always_check(A == 3.0);
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else always_check_no_entry();
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},
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TempA
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);
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}
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for (auto&& TempA : TempArray) {
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Visit(
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TOverloaded
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{
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[](int32 A) { always_check(A == 20); },
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[](int64 A) { always_check(A == 30ll); },
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[](float64 A) { always_check(A == 3.0); },
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[](auto A) { always_check_no_entry(); },
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},
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TempA
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);
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}
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}
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{
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@ -272,10 +327,10 @@ void TestVariant()
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bool bIsLValue;
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bool bIsRValue;
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auto TestQualifiers = [&bIsConst, &bIsLValue, &bIsRValue](auto&& Arg) -> int32
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auto TestQualifiers = [&bIsConst, &bIsLValue, &bIsRValue](auto&& A) -> int32
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{
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using T = decltype(Arg);
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always_check(Arg == 10);
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using T = decltype(A);
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always_check(A == 10);
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always_check(CConst<TRemoveReference<T>> == bIsConst);
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always_check(CLValueReference<T> == bIsLValue);
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always_check(CRValueReference<T> == bIsRValue);
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@ -287,7 +342,7 @@ void TestVariant()
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bIsRValue = false;
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TVariant<int32> TempLA = 10;
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auto ReturnLA = TempLA.Visit(TestQualifiers);
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auto ReturnLA = Visit(TestQualifiers, TempLA);
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always_check((CSameAs<int32, decltype(ReturnLA)>));
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bIsConst = true;
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@ -295,7 +350,7 @@ void TestVariant()
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bIsRValue = false;
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const TVariant<int32> TempLB = TempLA;
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auto ReturnLB = TempLB.Visit(TestQualifiers);
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auto ReturnLB = Visit(TestQualifiers, TempLB);
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always_check((CSameAs<int32, decltype(ReturnLB)>));
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bIsConst = false;
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@ -303,7 +358,7 @@ void TestVariant()
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bIsRValue = true;
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TVariant<int32> TempRA = 10;
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auto ReturnRA = MoveTemp(TempRA).Visit(TestQualifiers);
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auto ReturnRA = Visit(TestQualifiers, MoveTemp(TempRA));
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always_check((CSameAs<int32, decltype(ReturnRA)>));
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bIsConst = true;
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@ -311,7 +366,7 @@ void TestVariant()
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bIsRValue = true;
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const TVariant<int32> TempRB = TempLA;
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auto ReturnRB = MoveTemp(TempRB).Visit(TestQualifiers);
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auto ReturnRB = Visit(TestQualifiers, MoveTemp(TempRB));
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always_check((CSameAs<int32, decltype(ReturnRB)>));
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bIsConst = false;
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@ -319,7 +374,7 @@ void TestVariant()
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bIsRValue = false;
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TVariant<int32> TempLC = 10;
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auto ReturnLC = TempLC.Visit<int32>(TestQualifiers);
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auto ReturnLC = Visit<int32>(TestQualifiers, TempLC);
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always_check((CSameAs<int32, decltype(ReturnLC)>));
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bIsConst = true;
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@ -327,7 +382,7 @@ void TestVariant()
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bIsRValue = false;
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const TVariant<int32> TempLD = TempLC;
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auto ReturnLD = TempLD.Visit<int32>(TestQualifiers);
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auto ReturnLD = Visit<int32>(TestQualifiers, TempLD);
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always_check((CSameAs<int32, decltype(ReturnLD)>));
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bIsConst = false;
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@ -335,7 +390,7 @@ void TestVariant()
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bIsRValue = true;
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TVariant<int32> TempRC = 10;
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auto ReturnRC = MoveTemp(TempRC).Visit<int32>(TestQualifiers);
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auto ReturnRC = Visit<int32>(TestQualifiers, MoveTemp(TempRC));
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always_check((CSameAs<int32, decltype(ReturnRC)>));
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bIsConst = true;
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@ -343,7 +398,7 @@ void TestVariant()
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bIsRValue = true;
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const TVariant<int32> TempRD = TempLC;
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auto ReturnRD = MoveTemp(TempRD).Visit<int32>(TestQualifiers);
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auto ReturnRD = Visit<int32>(TestQualifiers, MoveTemp(TempRD));
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always_check((CSameAs<int32, decltype(ReturnRD)>));
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}
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@ -239,70 +239,6 @@ public:
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template <typename T> constexpr decltype(auto) Get( T& DefaultValue) & { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename T> constexpr decltype(auto) Get(const T& DefaultValue) const& { return HoldsAlternative<T>() ? GetValue<T>() : DefaultValue; }
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template <typename F> requires (true && ... && CInvocable<F, Ts>)
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FORCEINLINE decltype(auto) Visit(F&& Func) &
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
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using FInvokeImpl = ReturnType(*)(F&&, void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), *reinterpret_cast<Ts*>(This)); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename F> requires (true && ... && CInvocable<F, Ts>)
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FORCEINLINE decltype(auto) Visit(F&& Func) &&
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
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using FInvokeImpl = ReturnType(*)(F&&, void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), MoveTemp(*reinterpret_cast<Ts*>(This))); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename F> requires (true && ... && CInvocable<F, Ts>)
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FORCEINLINE decltype(auto) Visit(F&& Func) const&
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
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using FInvokeImpl = ReturnType(*)(F&&, const void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, const void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), *reinterpret_cast<const Ts*>(This)); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename F> requires (true && ... && CInvocable<F, Ts>)
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FORCEINLINE decltype(auto) Visit(F&& Func) const&&
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{
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checkf(IsValid(), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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using ReturnType = TCommonType<TInvokeResult<F, Ts>...>;
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using FInvokeImpl = ReturnType(*)(F&&, const void*);
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static constexpr FInvokeImpl InvokeImpl[] = { [](F&& Func, const void* This) -> ReturnType { return InvokeResult<ReturnType>(Forward<F>(Func), MoveTemp(*reinterpret_cast<const Ts*>(This))); }... };
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return InvokeImpl[GetIndex()](Forward<F>(Func), &Value);
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}
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
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FORCEINLINE R Visit(F&& Func) & { return Visit(Forward<F>(Func)); }
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
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FORCEINLINE R Visit(F&& Func) && { return MoveTemp(*this).Visit(Forward<F>(Func)); }
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
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FORCEINLINE R Visit(F&& Func) const& { return Visit(Forward<F>(Func)); }
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template <typename R, typename F> requires (true && ... && CInvocableResult<R, F, Ts>)
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FORCEINLINE R Visit(F&& Func) const&& { return MoveTemp(*this).Visit(Forward<F>(Func)); }
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constexpr void Reset()
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{
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if (GetIndex() == INDEX_NONE) return;
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@ -417,6 +353,152 @@ constexpr bool operator==(const TVariant<Ts...>& LHS, FInvalid)
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return !LHS.IsValid();
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}
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NAMESPACE_PRIVATE_BEGIN
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template <typename F, typename... VariantTypes>
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struct TVariantVisitImpl
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{
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struct GetTotalNum
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{
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static constexpr size_t Do()
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{
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if (sizeof...(VariantTypes) == 0) return 0;
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constexpr size_t VariantNums[] = { TVariantNum<TRemoveReference<VariantTypes>>... };
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size_t Result = 1;
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for (size_t Index = 0; Index < sizeof...(VariantTypes); ++Index)
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{
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Result *= VariantNums[Index];
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}
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return Result;
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};
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};
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struct EncodeIndices
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{
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static constexpr size_t Do(initializer_list<size_t> Indices)
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{
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constexpr size_t VariantNums[] = { TVariantNum<TRemoveReference<VariantTypes>>... };
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size_t Result = 0;
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for (size_t Index = 0; Index < sizeof...(VariantTypes); ++Index)
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{
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Result *= VariantNums[Index];
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Result += GetData(Indices)[Index];
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}
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return Result;
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};
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};
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struct DecodeExtent
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{
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static constexpr size_t Do(size_t EncodedIndex, size_t Extent)
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{
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constexpr size_t VariantNums[] = { TVariantNum<TRemoveReference<VariantTypes>>... };
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for (size_t Index = Extent + 1; Index < sizeof...(VariantTypes); ++Index)
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{
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EncodedIndex /= VariantNums[Index];
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}
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return EncodedIndex % VariantNums[Extent];
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};
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};
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template <size_t EncodedIndex, typename>
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struct InvokeEncoded;
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template <size_t EncodedIndex, size_t... ExtentIndices>
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struct InvokeEncoded<EncodedIndex, TIndexSequence<ExtentIndices...>>
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{
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static constexpr decltype(auto) Do(F&& Func, VariantTypes&&... Variants)
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{
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return Invoke(Forward<F>(Func), Forward<VariantTypes>(Variants).template GetValue<DecodeExtent::Do(EncodedIndex, ExtentIndices)>()...);
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}
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template <typename Ret>
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struct Result
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{
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static constexpr Ret Do(F&& Func, VariantTypes&&... Variants)
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{
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return InvokeResult<Ret>(Forward<F>(Func), Forward<VariantTypes>(Variants).template GetValue<DecodeExtent::Do(EncodedIndex, ExtentIndices)>()...);
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}
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};
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};
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template <typename>
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struct InvokeVariant;
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template <size_t... EncodedIndices>
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struct InvokeVariant<TIndexSequence<EncodedIndices...>>
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{
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static constexpr decltype(auto) Do(F&& Func, VariantTypes&&... Variants)
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{
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using ExtentIndices = TIndexSequenceFor<VariantTypes...>;
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using ResultType = TCommonType<decltype(InvokeEncoded<EncodedIndices, ExtentIndices>::Do(Forward<F>(Func), Forward<VariantTypes>(Variants)...))...>;
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using InvokeImplType = ResultType(*)(F&&, VariantTypes&&...);
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constexpr InvokeImplType InvokeImpl[] = { InvokeEncoded<EncodedIndices, ExtentIndices>::template Result<ResultType>::Do... };
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return InvokeImpl[EncodeIndices::Do({ Variants.GetIndex()... })](Forward<F>(Func), Forward<VariantTypes>(Variants)...);
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}
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template <typename Ret>
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struct Result
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{
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static constexpr Ret Do(F&& Func, VariantTypes&&... Variants)
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{
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using ExtentIndices = TIndexSequenceFor<VariantTypes...>;
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using InvokeImplType = Ret(*)(F&&, VariantTypes&&...);
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constexpr InvokeImplType InvokeImpl[] = { InvokeEncoded<EncodedIndices, ExtentIndices>::template Result<Ret>::Do... };
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return InvokeImpl[EncodeIndices::Do({ Variants.GetIndex()... })](Forward<F>(Func), Forward<VariantTypes>(Variants)...);
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}
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};
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};
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static constexpr decltype(auto) Do(F&& Func, VariantTypes&&... Variants)
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{
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return InvokeVariant<TMakeIndexSequence<GetTotalNum::Do()>>::Do(Forward<F>(Func), Forward<VariantTypes>(Variants)...);
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}
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template <typename Ret>
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struct Result
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{
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static constexpr Ret Do(F&& Func, VariantTypes&&... Variants)
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{
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return InvokeVariant<TMakeIndexSequence<GetTotalNum::Do()>>::template Result<Ret>::Do(Forward<F>(Func), Forward<VariantTypes>(Variants)...);
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}
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};
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};
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NAMESPACE_PRIVATE_END
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template <typename F, typename FirstVariantType, typename... VariantTypes>
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requires (CTVariant<TRemoveReference<FirstVariantType>> && (true && ... && CTVariant<TRemoveReference<VariantTypes>>))
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constexpr decltype(auto) Visit(F&& Func, FirstVariantType&& FirstVariant, VariantTypes&&... Variants)
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{
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checkf((true && ... && Variants.IsValid()), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return NAMESPACE_PRIVATE::TVariantVisitImpl<F, FirstVariantType, VariantTypes...>::Do(Forward<F>(Func), Forward<FirstVariantType>(FirstVariant), Forward<VariantTypes>(Variants)...);
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}
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template <typename Ret, typename F, typename FirstVariantType, typename... VariantTypes>
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requires (CTVariant<TRemoveReference<FirstVariantType>> && (true && ... && CTVariant<TRemoveReference<VariantTypes>>))
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constexpr Ret Visit(F&& Func, FirstVariantType&& FirstVariant, VariantTypes&&... Variants)
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{
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checkf((true && ... && Variants.IsValid()), TEXT("It is an error to call Visit() on an wrong TVariant. Please either check IsValid()."));
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return NAMESPACE_PRIVATE::TVariantVisitImpl<F, FirstVariantType, VariantTypes...>::template Result<Ret>::Do(Forward<F>(Func), Forward<FirstVariantType>(FirstVariant), Forward<VariantTypes>(Variants)...);
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}
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NAMESPACE_MODULE_END(Utility)
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NAMESPACE_MODULE_END(Redcraft)
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NAMESPACE_REDCRAFT_END
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