NazaraEngine/include/Nazara/Core/Flags.hpp

105 lines
3.5 KiB
C++

// Copyright (C) 2021 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
// This file is part of the "Nazara Engine - Core module"
// For conditions of distribution and use, see copyright notice in Config.hpp
#pragma once
#ifndef NAZARA_CORE_FLAGS_HPP
#define NAZARA_CORE_FLAGS_HPP
#include <Nazara/Prerequisites.hpp>
#include <type_traits>
namespace Nz
{
// From: https://www.justsoftwaresolutions.co.uk/cplusplus/using-enum-classes-as-bitfields.html
template<typename E>
struct EnumAsFlags
{
};
template<typename, typename = void>
struct IsEnumFlag : std::false_type {};
template<typename T>
struct IsEnumFlag<T, std::void_t<decltype(EnumAsFlags<T>::max)>> : std::true_type {};
template<typename, typename = void>
struct GetEnumAutoFlag : std::integral_constant<bool, true> {};
template<typename T>
struct GetEnumAutoFlag<T, std::void_t<decltype(T::AutoFlag)>> : std::integral_constant<bool, T::AutoFlag> {};
template<typename E>
class Flags
{
static_assert(std::is_enum_v<E>, "Type must be an enumeration");
static_assert(IsEnumFlag<E>(), "Enum has not been enabled as flags by an EnumAsFlags specialization");
static_assert(std::is_same_v<std::remove_cv_t<decltype(EnumAsFlags<E>::max)>, E>, "EnumAsFlags field max should be of the same type as the enum");
static constexpr std::size_t MaxValue = static_cast<std::size_t>(EnumAsFlags<E>::max);
static constexpr bool AutoFlag = GetEnumAutoFlag<E>();
using BitField16 = std::conditional_t<(MaxValue >= 8), UInt16, UInt8>;
using BitField32 = std::conditional_t<(MaxValue >= 16), UInt32, BitField16>;
public:
using BitField = std::conditional_t<(MaxValue >= 32), UInt64, BitField32>;
constexpr Flags(BitField value = 0);
constexpr Flags(E enumVal);
void Clear();
void Clear(const Flags& flags);
void Set(const Flags& flags);
constexpr bool Test(const Flags& flags) const;
explicit constexpr operator bool() const;
template<typename T, typename = std::enable_if_t<std::is_integral<T>::value && sizeof(T) >= sizeof(BitField)>> explicit constexpr operator T() const;
constexpr Flags operator~() const;
constexpr Flags operator&(const Flags& rhs) const;
constexpr Flags operator|(const Flags& rhs) const;
constexpr Flags operator^(const Flags& rhs) const;
constexpr bool operator==(const Flags& rhs) const;
constexpr bool operator!=(const Flags& rhs) const;
/*constexpr*/ Flags& operator|=(const Flags& rhs);
/*constexpr*/ Flags& operator&=(const Flags& rhs);
/*constexpr*/ Flags& operator^=(const Flags& rhs);
static constexpr BitField GetFlagValue(E enumValue);
static constexpr BitField ValueMask = BitField((UInt64(1) << (MaxValue + 1)) - 1);
private:
BitField m_value;
};
template<typename E> constexpr Flags<E> operator&(E lhs, Flags<E> rhs);
template<typename E> constexpr Flags<E> operator|(E lhs, Flags<E> rhs);
template<typename E> constexpr Flags<E> operator^(E lhs, Flags<E> rhs);
// Little hack to have them in both Nz and global scope
namespace FlagsOperators
{
template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator~(E lhs);
template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator&(E lhs, E rhs);
template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator|(E lhs, E rhs);
template<typename E> constexpr std::enable_if_t<IsEnumFlag<E>::value, Flags<E>> operator^(E lhs, E rhs);
}
using namespace FlagsOperators;
}
using namespace Nz::FlagsOperators;
#include <Nazara/Core/Flags.inl>
#endif // NAZARA_CORE_FLAGS_HPP