102 lines
3.3 KiB
C++
102 lines
3.3 KiB
C++
// Copyright (C) 2020 Jérôme Leclercq
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// This file is part of the "Nazara Engine - Core module"
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// For conditions of distribution and use, see copyright notice in Config.hpp
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#pragma once
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#ifndef NAZARA_FLAGS_HPP
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#define NAZARA_FLAGS_HPP
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#include <Nazara/Prerequisites.hpp>
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#include <type_traits>
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namespace Nz
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{
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// From: https://www.justsoftwaresolutions.co.uk/cplusplus/using-enum-classes-as-bitfields.html
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template<typename E>
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struct EnumAsFlags
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{
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};
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// From: https://stackoverflow.com/questions/11927032/sfinae-check-for-static-member-using-decltype
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template <typename T>
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class IsEnumFlag
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{
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template<typename U, typename = typename std::enable_if<!std::is_member_pointer<decltype(&EnumAsFlags<U>::max)>::value>::type>
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static std::true_type check(int);
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template <typename> static std::false_type check(...);
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public:
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static constexpr bool value = decltype(check<T>(0))::value;
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};
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template<typename E>
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class Flags
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{
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static_assert(std::is_enum<E>::value, "Type must be an enumeration");
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static_assert(IsEnumFlag<E>::value, "Enum has not been enabled as flags by an EnumAsFlags specialization");
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static constexpr std::size_t MaxValue = static_cast<std::size_t>(EnumAsFlags<E>::max);
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using BitField16 = std::conditional_t<(MaxValue >= 8), UInt16, UInt8>;
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using BitField32 = std::conditional_t<(MaxValue >= 16), UInt32, BitField16>;
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public:
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using BitField = std::conditional_t<(MaxValue >= 32), UInt64, BitField32>;
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constexpr Flags(BitField value = 0);
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constexpr Flags(E enumVal);
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void Clear();
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void Clear(const Flags& flags);
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void Set(const Flags& flags);
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constexpr bool Test(const Flags& flags) const;
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explicit constexpr operator bool() const;
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template<typename T, typename = std::enable_if_t<std::is_integral<T>::value && sizeof(T) >= sizeof(BitField)>> explicit constexpr operator T() const;
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constexpr Flags operator~() const;
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constexpr Flags operator&(const Flags& rhs) const;
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constexpr Flags operator|(const Flags& rhs) const;
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constexpr Flags operator^(const Flags& rhs) const;
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constexpr bool operator==(const Flags& rhs) const;
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constexpr bool operator!=(const Flags& rhs) const;
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/*constexpr*/ Flags& operator|=(const Flags& rhs);
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/*constexpr*/ Flags& operator&=(const Flags& rhs);
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/*constexpr*/ Flags& operator^=(const Flags& rhs);
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static constexpr BitField GetFlagValue(E enumValue);
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static constexpr BitField ValueMask = BitField((UInt64(1) << (MaxValue + 1)) - 1);
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private:
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BitField m_value;
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};
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template<typename E> constexpr Flags<E> operator&(E lhs, Flags<E> rhs);
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template<typename E> constexpr Flags<E> operator|(E lhs, Flags<E> rhs);
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template<typename E> constexpr Flags<E> operator^(E lhs, Flags<E> rhs);
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// Little hack to have them in both Nz and global scope
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namespace FlagsOperators
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{
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template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator~(E lhs);
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template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator&(E lhs, E rhs);
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template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator|(E lhs, E rhs);
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template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator^(E lhs, E rhs);
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}
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using namespace FlagsOperators;
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}
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using namespace Nz::FlagsOperators;
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#include <Nazara/Core/Flags.inl>
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#endif // NAZARA_FLAGS_HPP
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