aboutsummaryrefslogtreecommitdiff
path: root/src/common/slot_vector.h
blob: 34ff7de941fc9205851371d7a900beec113d634f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#pragma once

#include <algorithm>
#include <bit>
#include <numeric>
#include <type_traits>
#include <utility>
#include <vector>

#include "common/assert.h"
#include "common/common_types.h"
#include "common/polyfill_ranges.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>
    requires std::is_nothrow_move_assignable_v<T> && std::is_nothrow_move_constructible_v<T>
class SlotVector {
public:
    class Iterator {
        friend SlotVector<T>;

    public:
        constexpr Iterator() = default;

        Iterator& operator++() noexcept {
            const u64* const bitset = slot_vector->stored_bitset.data();
            const u32 size = static_cast<u32>(slot_vector->stored_bitset.size()) * 64;
            if (id.index < size) {
                do {
                    ++id.index;
                } while (id.index < size && !IsValid(bitset));
                if (id.index == size) {
                    id.index = SlotId::INVALID_INDEX;
                }
            }
            return *this;
        }

        Iterator operator++(int) noexcept {
            const Iterator copy{*this};
            ++*this;
            return copy;
        }

        bool operator==(const Iterator& other) const noexcept {
            return id.index == other.id.index;
        }

        bool operator!=(const Iterator& other) const noexcept {
            return id.index != other.id.index;
        }

        std::pair<SlotId, T*> operator*() const noexcept {
            return {id, std::addressof((*slot_vector)[id])};
        }

        T* operator->() const noexcept {
            return std::addressof((*slot_vector)[id]);
        }

    private:
        Iterator(SlotVector<T>* slot_vector_, SlotId id_) noexcept
            : slot_vector{slot_vector_}, id{id_} {}

        bool IsValid(const u64* bitset) const noexcept {
            return ((bitset[id.index / 64] >> (id.index % 64)) & 1) != 0;
        }

        SlotVector<T>* slot_vector;
        SlotId id;
    };

    ~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);
    }

    [[nodiscard]] Iterator begin() noexcept {
        const auto it = std::ranges::find_if(stored_bitset, [](u64 value) { return value != 0; });
        if (it == stored_bitset.end()) {
            return end();
        }
        const u32 word_index = static_cast<u32>(std::distance(it, stored_bitset.begin()));
        const SlotId first_id{word_index * 64 + static_cast<u32>(std::countr_zero(*it))};
        return Iterator(this, first_id);
    }

    [[nodiscard]] Iterator end() noexcept {
        return Iterator(this, SlotId{SlotId::INVALID_INDEX});
    }

    [[nodiscard]] size_t size() const noexcept {
        return values_capacity - free_list.size();
    }

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);
    }
};