Add bitset utility functions

Implement utility functions to set, clear, toggle, and query a bitset
for more concise code.

Author: falbrechtskirchinger

libs/common/include/s25util/enumUtils.h

@@ -6,6 +6,17 @@
 
 #include <type_traits>
 
+// TODO Find a better home; could be useful elsewhere
+#if __cplusplus >= 201703L
+#    define ENUM_UTILS_NODISCARD [[nodiscard]]
+#elif defined(__clang__) || defined(__GNUC__)
+#    define ENUM_UTILS_NODISCARD __attribute__((warn_unused_result))
+#elif defined(_MSC_VER)
+#    define ENUM_UTILS_NODISCARD _Check_return_
+#else
+#    define ENUM_UTILS_NODISCARD
+#endif
+
 template<typename Enum>
 struct IsBitset : std::false_type
 {};
@@ -56,6 +67,34 @@ constexpr auto operator^=(Enum& lhs, Enum rhs) noexcept
     return lhs;
 }
 
+namespace bitset {
+template<typename Enum, std::enable_if_t<IsValidBitset<Enum>::value, int> = 0>
+ENUM_UTILS_NODISCARD constexpr Enum clear(Enum val, Enum flag)
+{
+    using T = std::underlying_type_t<Enum>;
+    return val & Enum(~static_cast<T>(flag));
+}
+
+template<typename Enum, std::enable_if_t<IsValidBitset<Enum>::value, int> = 0>
+ENUM_UTILS_NODISCARD constexpr Enum set(Enum val, Enum flag, bool state = true)
+{
+    using T = std::underlying_type_t<Enum>;
+    return state ? (val | flag) : (val & Enum(~static_cast<T>(flag)));
+}
+
+template<typename Enum, std::enable_if_t<IsValidBitset<Enum>::value, int> = 0>
+ENUM_UTILS_NODISCARD constexpr Enum toggle(Enum val, Enum flag)
+{
+    return val ^ flag;
+}
+
+template<typename Enum, std::enable_if_t<IsValidBitset<Enum>::value, int> = 0>
+constexpr bool isSet(Enum val, Enum flag)
+{
+    return (val & flag) != Enum(0);
+}
+} // namespace bitset
+
 /// Makes a strongly typed enum usable as a bitset
 #define MAKE_BITSET_STRONG(Type)                                         \
     template<>                                                           \
@@ -64,3 +103,5 @@ constexpr auto operator^=(Enum& lhs, Enum rhs) noexcept
     /* NOLINTNEXTLINE(bugprone-macro-parentheses) */                     \
     static_assert(std::is_unsigned<std::underlying_type_t<Type>>::value, \
                   #Type " must use unsigned type as the underlying type")
+
+#undef ENUM_UTILS_NODISCARD