citra/src/common/slot_vector.h

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// Copyright 2020 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <bit>
#include <compare>
#include <numeric>
#include <type_traits>
#include <utility>
#include <vector>
#include "common/assert.h"
#include "common/common_types.h"
namespace Common {
struct SlotId {
static constexpr u32 INVALID_INDEX = std::numeric_limits<u32>::max();
constexpr auto operator<=>(const SlotId&) const noexcept = default;
constexpr explicit operator bool() const noexcept {
return index != INVALID_INDEX;
}
u32 index = INVALID_INDEX;
};
template <class T>
class SlotVector {
public:
~SlotVector() noexcept {
size_t index = 0;
for (u64 bits : stored_bitset) {
for (size_t bit = 0; bits; ++bit, bits >>= 1) {
if ((bits & 1) != 0) {
values[index + bit].object.~T();
}
}
index += 64;
}
delete[] values;
}
[[nodiscard]] T& operator[](SlotId id) noexcept {
ValidateIndex(id);
return values[id.index].object;
}
[[nodiscard]] const T& operator[](SlotId id) const noexcept {
ValidateIndex(id);
return values[id.index].object;
}
template <typename... Args>
[[nodiscard]] SlotId insert(Args&&... args) noexcept {
const u32 index = FreeValueIndex();
new (&values[index].object) T(std::forward<Args>(args)...);
SetStorageBit(index);
return SlotId{index};
}
void erase(SlotId id) noexcept {
values[id.index].object.~T();
free_list.push_back(id.index);
ResetStorageBit(id.index);
}
private:
struct NonTrivialDummy {
NonTrivialDummy() noexcept {}
};
union Entry {
Entry() noexcept : dummy{} {}
~Entry() noexcept {}
NonTrivialDummy dummy;
T object;
};
void SetStorageBit(u32 index) noexcept {
stored_bitset[index / 64] |= u64(1) << (index % 64);
}
void ResetStorageBit(u32 index) noexcept {
stored_bitset[index / 64] &= ~(u64(1) << (index % 64));
}
bool ReadStorageBit(u32 index) noexcept {
return ((stored_bitset[index / 64] >> (index % 64)) & 1) != 0;
}
void ValidateIndex(SlotId id) const noexcept {
DEBUG_ASSERT(id);
DEBUG_ASSERT(id.index / 64 < stored_bitset.size());
DEBUG_ASSERT(((stored_bitset[id.index / 64] >> (id.index % 64)) & 1) != 0);
}
[[nodiscard]] u32 FreeValueIndex() noexcept {
if (free_list.empty()) {
Reserve(values_capacity ? (values_capacity << 1) : 1);
}
const u32 free_index = free_list.back();
free_list.pop_back();
return free_index;
}
void Reserve(size_t new_capacity) noexcept {
Entry* const new_values = new Entry[new_capacity];
size_t index = 0;
for (u64 bits : stored_bitset) {
for (size_t bit = 0; bits; ++bit, bits >>= 1) {
const size_t i = index + bit;
if ((bits & 1) == 0) {
continue;
}
T& old_value = values[i].object;
new (&new_values[i].object) T(std::move(old_value));
old_value.~T();
}
index += 64;
}
stored_bitset.resize((new_capacity + 63) / 64);
const size_t old_free_size = free_list.size();
free_list.resize(old_free_size + (new_capacity - values_capacity));
std::iota(free_list.begin() + old_free_size, free_list.end(),
static_cast<u32>(values_capacity));
delete[] values;
values = new_values;
values_capacity = new_capacity;
}
Entry* values = nullptr;
size_t values_capacity = 0;
std::vector<u64> stored_bitset;
std::vector<u32> free_list;
};
} // namespace Common
template <>
struct std::hash<Common::SlotId> {
size_t operator()(const Common::SlotId& id) const noexcept {
return std::hash<u32>{}(id.index);
}
};