// SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <type_traits>
#include "common/assert.h"
namespace Common {
namespace detail {
template <typename T, size_t Size, size_t Align>
struct TypedStorageImpl {
alignas(Align) u8 storage_[Size];
};
} // namespace detail
template <typename T>
using TypedStorage = detail::TypedStorageImpl<T, sizeof(T), alignof(T)>;
template <typename T>
static constexpr T* GetPointer(TypedStorage<T>& ts) {
return static_cast<T*>(static_cast<void*>(std::addressof(ts.storage_)));
}
template <typename T>
static constexpr const T* GetPointer(const TypedStorage<T>& ts) {
return static_cast<const T*>(static_cast<const void*>(std::addressof(ts.storage_)));
}
namespace impl {
template <size_t MaxDepth>
struct OffsetOfUnionHolder {
template <typename ParentType, typename MemberType, size_t Offset>
union UnionImpl {
using PaddingMember = char;
static constexpr size_t GetOffset() {
return Offset;
}
#pragma pack(push, 1)
struct {
PaddingMember padding[Offset];
MemberType members[(sizeof(ParentType) / sizeof(MemberType)) + 1];
} data;
#pragma pack(pop)
UnionImpl<ParentType, MemberType, Offset + 1> next_union;
};
template <typename ParentType, typename MemberType>
union UnionImpl<ParentType, MemberType, 0> {
static constexpr size_t GetOffset() {
return 0;
}
struct {
MemberType members[(sizeof(ParentType) / sizeof(MemberType)) + 1];
} data;
UnionImpl<ParentType, MemberType, 1> next_union;
};
template <typename ParentType, typename MemberType>
union UnionImpl<ParentType, MemberType, MaxDepth> {};
};
template <typename ParentType, typename MemberType>
struct OffsetOfCalculator {
using UnionHolder =
typename OffsetOfUnionHolder<sizeof(MemberType)>::template UnionImpl<ParentType, MemberType,
0>;
union Union {
char c{};
UnionHolder first_union;
TypedStorage<ParentType> parent;
constexpr Union() : c() {}
};
static constexpr Union U = {};
static constexpr const MemberType* GetNextAddress(const MemberType* start,
const MemberType* target) {
while (start < target) {
start++;
}
return start;
}
static constexpr std::ptrdiff_t GetDifference(const MemberType* start,
const MemberType* target) {
return (target - start) * sizeof(MemberType);
}
template <typename CurUnion>
static constexpr std::ptrdiff_t OffsetOfImpl(MemberType ParentType::*member,
CurUnion& cur_union) {
constexpr size_t Offset = CurUnion::GetOffset();
const auto target = std::addressof(GetPointer(U.parent)->*member);
const auto start = std::addressof(cur_union.data.members[0]);
const auto next = GetNextAddress(start, target);
if (next != target) {
if constexpr (Offset < sizeof(MemberType) - 1) {
return OffsetOfImpl(member, cur_union.next_union);
} else {
UNREACHABLE();
}
}
return static_cast<ptrdiff_t>(static_cast<size_t>(next - start) * sizeof(MemberType) +
Offset);
}
static constexpr std::ptrdiff_t OffsetOf(MemberType ParentType::*member) {
return OffsetOfImpl(member, U.first_union);
}
};
template <typename T>
struct GetMemberPointerTraits;
template <typename P, typename M>
struct GetMemberPointerTraits<M P::*> {
using Parent = P;
using Member = M;
};
template <auto MemberPtr>
using GetParentType = typename GetMemberPointerTraits<decltype(MemberPtr)>::Parent;
template <auto MemberPtr>
using GetMemberType = typename GetMemberPointerTraits<decltype(MemberPtr)>::Member;
template <auto MemberPtr, typename RealParentType = GetParentType<MemberPtr>>
constexpr std::ptrdiff_t OffsetOf() {
using DeducedParentType = GetParentType<MemberPtr>;
using MemberType = GetMemberType<MemberPtr>;
static_assert(std::is_base_of<DeducedParentType, RealParentType>::value ||
std::is_same<RealParentType, DeducedParentType>::value);
return OffsetOfCalculator<RealParentType, MemberType>::OffsetOf(MemberPtr);
};
} // namespace impl
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType& GetParentReference(impl::GetMemberType<MemberPtr>* member) {
std::ptrdiff_t Offset = impl::OffsetOf<MemberPtr, RealParentType>();
return *static_cast<RealParentType*>(
static_cast<void*>(static_cast<uint8_t*>(static_cast<void*>(member)) - Offset));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType const& GetParentReference(impl::GetMemberType<MemberPtr> const* member) {
std::ptrdiff_t Offset = impl::OffsetOf<MemberPtr, RealParentType>();
return *static_cast<const RealParentType*>(static_cast<const void*>(
static_cast<const uint8_t*>(static_cast<const void*>(member)) - Offset));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType* GetParentPointer(impl::GetMemberType<MemberPtr>* member) {
return std::addressof(GetParentReference<MemberPtr, RealParentType>(member));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType const* GetParentPointer(impl::GetMemberType<MemberPtr> const* member) {
return std::addressof(GetParentReference<MemberPtr, RealParentType>(member));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType& GetParentReference(impl::GetMemberType<MemberPtr>& member) {
return GetParentReference<MemberPtr, RealParentType>(std::addressof(member));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType const& GetParentReference(impl::GetMemberType<MemberPtr> const& member) {
return GetParentReference<MemberPtr, RealParentType>(std::addressof(member));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType* GetParentPointer(impl::GetMemberType<MemberPtr>& member) {
return std::addressof(GetParentReference<MemberPtr, RealParentType>(member));
}
template <auto MemberPtr, typename RealParentType = impl::GetParentType<MemberPtr>>
constexpr RealParentType const* GetParentPointer(impl::GetMemberType<MemberPtr> const& member) {
return std::addressof(GetParentReference<MemberPtr, RealParentType>(member));
}
} // namespace Common
