From 60b4ec6f585240daa9c29767057c01220c7d2a49 Mon Sep 17 00:00:00 2001
From: _Redstone_c_ <myredstone1024@gmail.com>
Date: Fri, 10 Dec 2021 21:43:57 +0800
Subject: [PATCH] feat(typetraits): add TypeTraits/PrimaryType.h and the
 corresponding testing

---
 .../Private/Testing/TypeTraitsTesting.cpp     | 113 ++++++++++++++++++
 .../Source/Public/Testing/TypeTraitsTesting.h |  13 ++
 .../Source/Public/TypeTraits/HelperClasses.h  |  52 ++++++++
 .../Source/Public/TypeTraits/PrimaryType.h    |  44 +++++++
 4 files changed, 222 insertions(+)
 create mode 100644 Redcraft.Utility/Source/Private/Testing/TypeTraitsTesting.cpp
 create mode 100644 Redcraft.Utility/Source/Public/Testing/TypeTraitsTesting.h
 create mode 100644 Redcraft.Utility/Source/Public/TypeTraits/HelperClasses.h
 create mode 100644 Redcraft.Utility/Source/Public/TypeTraits/PrimaryType.h

diff --git a/Redcraft.Utility/Source/Private/Testing/TypeTraitsTesting.cpp b/Redcraft.Utility/Source/Private/Testing/TypeTraitsTesting.cpp
new file mode 100644
index 0000000..842d6eb
--- /dev/null
+++ b/Redcraft.Utility/Source/Private/Testing/TypeTraitsTesting.cpp
@@ -0,0 +1,113 @@
+#include "Testing/TypeTraitsTesting.h"
+#include "Misc/AssertionMacros.h"
+#include "TypeTraits/HelperClasses.h"
+#include "TypeTraits/PrimaryType.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+// Warning: The test here is not a complete test, it is only used to determine whether the environment supports the traits
+
+int32 TestObject;
+void TestFunction() { }
+
+struct FTestStruct { };
+
+enum ETestEnum { };
+
+enum class ETestEnumClass { };
+
+union FTestUnion { };
+
+void TestTypeTraits()
+{
+	// HelperClasses.h
+
+	always_check(TypeTraits::TIntegralConstant<1>::Value == 1);
+	always_check(static_cast<int32>(TypeTraits::TIntegralConstant<2>::Value) == 2);
+	always_check(TypeTraits::TIntegralConstant<3>() == 3);
+
+	always_check(!TypeTraits::FFalse::Value);
+	always_check(TypeTraits::FTrue::Value);
+
+	always_check(TypeTraits::TAnd<TypeTraits::FTrue>::Value);
+	always_check(!TypeTraits::TAnd<TypeTraits::FFalse>::Value);
+	always_check((TypeTraits::TAnd<TypeTraits::FTrue, TypeTraits::FTrue>::Value));
+	always_check(!(TypeTraits::TAnd<TypeTraits::FFalse, TypeTraits::FTrue>::Value));
+	always_check(!(TypeTraits::TAnd<TypeTraits::FTrue, TypeTraits::FFalse>::Value));
+	always_check(!(TypeTraits::TAnd<TypeTraits::FFalse, TypeTraits::FFalse>::Value));
+
+	always_check(TypeTraits::TOr<TypeTraits::FTrue>::Value);
+	always_check(!TypeTraits::TOr<TypeTraits::FFalse>::Value);
+	always_check((TypeTraits::TOr<TypeTraits::FTrue, TypeTraits::FTrue>::Value));
+	always_check((TypeTraits::TOr<TypeTraits::FFalse, TypeTraits::FTrue>::Value));
+	always_check((TypeTraits::TOr<TypeTraits::FTrue, TypeTraits::FFalse>::Value));
+	always_check(!(TypeTraits::TOr<TypeTraits::FFalse, TypeTraits::FFalse>::Value));
+
+	always_check(!TypeTraits::TNot<TypeTraits::FTrue>::Value);
+	always_check(TypeTraits::TNot<TypeTraits::FFalse>::Value);
+
+	// PrimaryType.h
+
+	always_check(!TypeTraits::TIsVoid<int32>::Value);
+	always_check(TypeTraits::TIsVoid<void>::Value);
+	always_check(TypeTraits::TIsVoid<const void>::Value);
+	always_check(TypeTraits::TIsVoid<const volatile void>::Value);
+	always_check(TypeTraits::TIsVoid<volatile void>::Value);
+
+	always_check(!TypeTraits::TIsNullPointer<int32>::Value);
+	always_check(TypeTraits::TIsNullPointer<nullptr_t>::Value);
+
+	always_check(TypeTraits::TIsIntegral<int32>::Value);
+	always_check(!TypeTraits::TIsIntegral<float>::Value);
+
+	always_check(!TypeTraits::TIsFloatingPoint<int32>::Value);
+	always_check(TypeTraits::TIsFloatingPoint<float>::Value);
+
+	always_check(!TypeTraits::TIsArray<int32>::Value);
+	always_check(TypeTraits::TIsArray<int32[]>::Value);
+	always_check(TypeTraits::TIsArray<int32[10]>::Value);
+
+	always_check(!TypeTraits::TIsPointer<int32>::Value);
+	always_check(TypeTraits::TIsPointer<int32*>::Value);
+
+	always_check(!TypeTraits::TIsLValueReference<int32>::Value);
+	always_check(TypeTraits::TIsLValueReference<int32&>::Value);
+	always_check(!TypeTraits::TIsLValueReference<int32&&>::Value);
+	
+	always_check(!TypeTraits::TIsRValueReference<int32>::Value);
+	always_check(!TypeTraits::TIsRValueReference<int32&>::Value);
+	always_check(TypeTraits::TIsRValueReference<int32&&>::Value);
+
+	always_check(TypeTraits::TIsMemberObjectPointer<int32(FTestStruct::*)>::Value);
+	always_check(!TypeTraits::TIsMemberObjectPointer<int32(FTestStruct::*)()>::Value);
+
+	always_check(!TypeTraits::TIsMemberFunctionPointer<int32(FTestStruct::*)>::Value);
+	always_check(TypeTraits::TIsMemberFunctionPointer<int32(FTestStruct::*)()>::Value);
+
+	always_check(!TypeTraits::TIsEnum<int32>::Value);
+	always_check(!TypeTraits::TIsEnum<FTestStruct>::Value);
+	always_check(TypeTraits::TIsEnum<ETestEnum>::Value);
+	always_check(TypeTraits::TIsEnum<ETestEnumClass>::Value);
+
+	always_check(!TypeTraits::TIsUnion<int32>::Value);
+	always_check(!TypeTraits::TIsUnion<FTestStruct>::Value);
+	always_check(TypeTraits::TIsUnion<FTestUnion>::Value);
+
+	always_check(!TypeTraits::TIsUnion<int32>::Value);
+	always_check(!TypeTraits::TIsUnion<FTestStruct>::Value);
+	always_check(TypeTraits::TIsUnion<FTestUnion>::Value);
+
+	always_check(!TypeTraits::TIsFunction<int32>::Value);
+	always_check(!TypeTraits::TIsFunction<FTestStruct>::Value);
+	always_check(!TypeTraits::TIsFunction<FTestUnion>::Value);
+	always_check(TypeTraits::TIsFunction<int32(int32)>::Value);
+
+	always_check(!TypeTraits::TIsEnumClass<ETestEnum>::Value);
+	always_check(TypeTraits::TIsEnumClass<ETestEnumClass>::Value);
+}
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END
diff --git a/Redcraft.Utility/Source/Public/Testing/TypeTraitsTesting.h b/Redcraft.Utility/Source/Public/Testing/TypeTraitsTesting.h
new file mode 100644
index 0000000..369b559
--- /dev/null
+++ b/Redcraft.Utility/Source/Public/Testing/TypeTraitsTesting.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include "CoreTypes.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+void REDCRAFTUTILITY_API TestTypeTraits();
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END
diff --git a/Redcraft.Utility/Source/Public/TypeTraits/HelperClasses.h b/Redcraft.Utility/Source/Public/TypeTraits/HelperClasses.h
new file mode 100644
index 0000000..e2bc9f4
--- /dev/null
+++ b/Redcraft.Utility/Source/Public/TypeTraits/HelperClasses.h
@@ -0,0 +1,52 @@
+#pragma once
+
+#include "CoreTypes.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+NAMESPACE_BEGIN(TypeTraits)
+
+template <typename InType, InType InValue>
+struct TConstant
+{
+	using Type = InType;
+	static constexpr Type Value = InValue;
+	constexpr operator Type() const { return Value; }
+	constexpr Type operator()() const { return Value; }
+};
+
+template <bool InValue>
+using TBoolConstant = TConstant<bool, InValue>;
+
+template <int32 InValue>
+using TIntegralConstant = TConstant<int32, InValue>;
+
+using FTrue  = TBoolConstant<true>;
+using FFalse = TBoolConstant<false>;
+
+template <typename... Types> 
+struct TAnd;
+
+template <typename LHS, typename... RHS>
+struct TAnd<LHS, RHS...> : TBoolConstant<LHS::Value&& TAnd<RHS...>::Value> { };
+
+template <>
+struct TAnd<> : FTrue { };
+ 
+template <typename... Types>
+struct TOr;
+
+template <typename LHS, typename... RHS>
+struct TOr<LHS, RHS...> : TBoolConstant<LHS::Value || TOr<RHS...>::Value> { };
+
+template <>
+struct TOr<> : FFalse { };
+ 
+template <typename Type>
+struct TNot : TBoolConstant<!Type::Value> { };
+
+NAMESPACE_END(TypeTraits)
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END
diff --git a/Redcraft.Utility/Source/Public/TypeTraits/PrimaryType.h b/Redcraft.Utility/Source/Public/TypeTraits/PrimaryType.h
new file mode 100644
index 0000000..847c9ac
--- /dev/null
+++ b/Redcraft.Utility/Source/Public/TypeTraits/PrimaryType.h
@@ -0,0 +1,44 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "TypeTraits/HelperClasses.h"
+
+#include <type_traits>
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+NAMESPACE_BEGIN(TypeTraits)
+
+template <typename T> struct TIsVoid                  : TBoolConstant<NAMESPACE_STD::is_void_v<T>>                    { };
+template <typename T> struct TIsNullPointer           : TBoolConstant<NAMESPACE_STD::is_null_pointer_v<T>>            { };
+template <typename T> struct TIsIntegral              : TBoolConstant<NAMESPACE_STD::is_integral_v<T>>                { };
+template <typename T> struct TIsFloatingPoint         : TBoolConstant<NAMESPACE_STD::is_floating_point_v<T>>          { };
+template <typename T> struct TIsArray                 : TBoolConstant<NAMESPACE_STD::is_array_v<T>>                   { };
+template <typename T> struct TIsPointer               : TBoolConstant<NAMESPACE_STD::is_pointer_v<T>>                 { };
+template <typename T> struct TIsLValueReference       : TBoolConstant<NAMESPACE_STD::is_lvalue_reference_v<T>>        { };
+template <typename T> struct TIsRValueReference       : TBoolConstant<NAMESPACE_STD::is_rvalue_reference_v<T>>        { };
+template <typename T> struct TIsMemberObjectPointer   : TBoolConstant<NAMESPACE_STD::is_member_object_pointer_v<T>>   { };
+template <typename T> struct TIsMemberFunctionPointer : TBoolConstant<NAMESPACE_STD::is_member_function_pointer_v<T>> { };
+template <typename T> struct TIsEnum                  : TBoolConstant<NAMESPACE_STD::is_enum_v<T>>                    { };
+template <typename T> struct TIsUnion                 : TBoolConstant<NAMESPACE_STD::is_union_v<T>>                   { };
+template <typename T> struct TIsClass                 : TBoolConstant<NAMESPACE_STD::is_class_v<T>>                   { };
+template <typename T> struct TIsFunction              : TBoolConstant<NAMESPACE_STD::is_function_v<T>>                { };
+
+NAMESPACE_PRIVATE_BEGIN
+
+static char(&Resolve(int))[2];
+static char Resolve(...);
+
+template <typename T>
+struct TIsEnumConvertibleToInt : TBoolConstant<sizeof(Resolve(T())) - 1> { };
+
+NAMESPACE_PRIVATE_END
+
+template <typename T>
+struct TIsEnumClass : TBoolConstant<TAnd<TIsEnum<T>, TNot<NAMESPACE_PRIVATE::TIsEnumConvertibleToInt<T>>>::Value> { };
+
+NAMESPACE_END(TypeTraits)
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END