From ca9605215b31dccb946328fa315d8b6ca3fc9ce3 Mon Sep 17 00:00:00 2001
From: Kitzunu <24550914+Kitzunu@users.noreply.github.com>
Date: Fri, 17 Sep 2021 14:51:01 +0200
Subject: [PATCH] feat(Core/Misc): improve enum flags with type safe operators
 (#7865)

---
 src/common/Utilities/EnumFlag.h | 119 ++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 src/common/Utilities/EnumFlag.h

diff --git a/src/common/Utilities/EnumFlag.h b/src/common/Utilities/EnumFlag.h
new file mode 100644
index 000000000..b9fc9168e
--- /dev/null
+++ b/src/common/Utilities/EnumFlag.h
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2016+     AzerothCore <www.azerothcore.org>, released under GNU GPL v2 license, you may redistribute it and/or modify it under version 2 of the License, or (at your option), any later version.
+ * Copyright (C) 2008-2021 TrinityCore <http://www.trinitycore.org/>
+ */
+
+#ifndef EnumFlag_h__
+#define EnumFlag_h__
+
+#include <type_traits>
+
+template<typename T>
+constexpr bool IsEnumFlag(T) { return false; }
+
+#define DEFINE_ENUM_FLAG(enumType) constexpr bool IsEnumFlag(enumType) { return true; }
+
+namespace EnumTraits
+{
+    template<typename T>
+    using IsFlag = std::integral_constant<bool, IsEnumFlag(T{})>;
+}
+
+template<typename T, std::enable_if_t<EnumTraits::IsFlag<T>::value, std::nullptr_t> = nullptr>
+inline constexpr T operator&(T left, T right)
+{
+    return static_cast<T>(static_cast<std::underlying_type_t<T>>(left) & static_cast<std::underlying_type_t<T>>(right));
+}
+
+template<typename T, std::enable_if_t<EnumTraits::IsFlag<T>::value, std::nullptr_t> = nullptr>
+inline constexpr T& operator&=(T& left, T right)
+{
+    return left = left & right;
+}
+
+template<typename T, std::enable_if_t<EnumTraits::IsFlag<T>::value, std::nullptr_t> = nullptr>
+inline constexpr T operator|(T left, T right)
+{
+    return static_cast<T>(static_cast<std::underlying_type_t<T>>(left) | static_cast<std::underlying_type_t<T>>(right));
+}
+
+template<typename T, std::enable_if_t<EnumTraits::IsFlag<T>::value, std::nullptr_t> = nullptr>
+inline constexpr T& operator|=(T& left, T right)
+{
+    return left = left | right;
+}
+
+template<typename T, std::enable_if_t<EnumTraits::IsFlag<T>::value, std::nullptr_t> = nullptr>
+inline constexpr T operator~(T value)
+{
+    return static_cast<T>(~static_cast<std::underlying_type_t<T>>(value));
+}
+
+template<typename T>
+class EnumFlag
+{
+    static_assert(EnumTraits::IsFlag<T>::value, "EnumFlag must be used only with enums that are specify EnumFlag::IsFlag");
+
+public:
+    /*implicit*/ constexpr EnumFlag(T value) : _value(value)
+    {
+    }
+
+    constexpr EnumFlag& operator&=(EnumFlag right)
+    {
+        _value &= right._value;
+        return *this;
+    }
+
+    constexpr friend EnumFlag operator&(EnumFlag left, EnumFlag right)
+    {
+        return left &= right;
+    }
+
+    constexpr EnumFlag& operator|=(EnumFlag right)
+    {
+        _value |= right._value;
+        return *this;
+    }
+
+    constexpr friend EnumFlag operator|(EnumFlag left, EnumFlag right)
+    {
+        return left |= right;
+    }
+
+    constexpr EnumFlag operator~() const
+    {
+        return static_cast<T>(~static_cast<std::underlying_type_t<T>>(_value));
+    }
+
+    constexpr void RemoveFlag(EnumFlag flag)
+    {
+        _value &= ~flag._value;
+    }
+
+    constexpr bool HasFlag(T flag) const
+    {
+        using i = std::underlying_type_t<T>;
+        return static_cast<i>(_value & flag) != static_cast<i>(0);
+    }
+
+    constexpr bool HasAllFlags(T flags) const
+    {
+        return (_value & flags) == flags;
+    }
+
+    constexpr operator T() const
+    {
+        return _value;
+    }
+
+    constexpr std::underlying_type_t<T> AsUnderlyingType() const
+    {
+        return static_cast<std::underlying_type_t<T>>(_value);
+    }
+
+private:
+    T _value;
+};
+
+#endif // EnumFlag_h__