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Diffstat (limited to 'asl/containers/hash_set.hpp')
| -rw-r--r-- | asl/containers/hash_set.hpp | 418 |
1 files changed, 418 insertions, 0 deletions
diff --git a/asl/containers/hash_set.hpp b/asl/containers/hash_set.hpp new file mode 100644 index 0000000..97a37f2 --- /dev/null +++ b/asl/containers/hash_set.hpp @@ -0,0 +1,418 @@ +#pragma once + +#include "asl/base/annotations.hpp" +#include "asl/base/utility.hpp" +#include "asl/base/meta.hpp" +#include "asl/memory/allocator.hpp" +#include "asl/memory/memory.hpp" +#include "asl/types/maybe_uninit.hpp" +#include "asl/hashing/hash.hpp" + +namespace asl +{ + +template<typename H, typename T> +concept key_hasher = requires (const T& value) +{ + { H::hash(value) } -> same_as<uint64_t>; +}; + +template<hashable T> +struct default_key_hasher +{ + constexpr static uint64_t hash(const T& value) + { + return hash_value(value); + } +}; + +template<typename C, typename U, typename V = U> +concept key_comparator = requires(const U& a, const V& b) +{ + { C::eq(a, b) } -> same_as<bool>; +}; + +template<equality_comparable T> +struct default_key_comparator +{ + constexpr static bool eq(const T& a, const T& b) + { + return a == b; + } +}; + +template< + is_object T, + allocator Allocator = DefaultAllocator, + key_hasher<T> KeyHasher = default_key_hasher<T>, + key_comparator<T> KeyComparator = default_key_comparator<T> +> +requires moveable<T> +class hash_set +{ +protected: + static constexpr uint8_t kHasValue = 0x80; + static constexpr uint8_t kHashMask = 0x7f; + static constexpr uint8_t kEmpty = 0x00; + static constexpr uint8_t kTombstone = 0x01; + + static constexpr isize_t kMinCapacity = 8; + + // Important so we can memzero the tags + static_assert(kEmpty == 0); + + uint8_t* m_tags{}; + maybe_uninit<T>* m_values{}; + isize_t m_capacity{}; + isize_t m_size{}; + + ASL_NO_UNIQUE_ADDRESS Allocator m_allocator; + + constexpr isize_t max_size() const + { + // Max load factor is 75% + return (m_capacity >> 1) + (m_capacity >> 2); + } + + static isize_t size_to_capacity(isize_t size) + { + ASL_ASSERT(size > 0); + return max<isize_t>( + kMinCapacity, + static_cast<isize_t>(round_up_pow2((static_cast<uint64_t>(size) * 4 + 2) / 3))); + } + + static void insert_inner( + T&& value, + uint8_t* tags, + maybe_uninit<T>* values, + isize_t capacity, + isize_t* size) + { + ASL_ASSERT(*size < capacity); + + const auto result = find_slot_insert(value, tags, values, capacity); + + // NOLINTBEGIN(*-pointer-arithmetic) + + ASL_ASSERT(result.first_available_index >= 0); + + if (result.already_present_index != result.first_available_index) + { + ASL_ASSERT((tags[result.first_available_index] & kHasValue) == 0); + if (result.already_present_index >= 0) + { + ASL_ASSERT((tags[result.already_present_index] & kHasValue) != 0); + values[result.already_present_index].destroy_unsafe(); + tags[result.already_present_index] = kTombstone; + } + else + { + *size += 1; + } + + values[result.first_available_index].construct_unsafe(ASL_MOVE(value)); + tags[result.first_available_index] = result.tag; + } + + // NOLINTEND(*-pointer-arithmetic) + } + + void grow_and_rehash() + { + grow_and_rehash(max(kMinCapacity, m_capacity * 2)); + } + + void grow_and_rehash(isize_t new_capacity) + { + ASL_ASSERT(new_capacity >= kMinCapacity && is_pow2(new_capacity) && new_capacity > m_capacity); + + auto* new_tags = reinterpret_cast<uint8_t*>(m_allocator.alloc(layout::array<uint8_t>(new_capacity))); + auto* new_values = reinterpret_cast<maybe_uninit<T>*>(m_allocator.alloc(layout::array<maybe_uninit<T>>(new_capacity))); + asl::memzero(new_tags, new_capacity); + + isize_t new_size = 0; + + if (m_size > 0) + { + // NOLINTBEGIN(*-pointer-arithmetic) + for (isize_t i = 0; i < m_capacity; ++i) + { + if ((m_tags[i] & kHasValue) == 0) { continue; } + + insert_inner(ASL_MOVE(m_values[i].as_init_unsafe()), new_tags, new_values, new_capacity, &new_size); + + // Destroy now so that destroy() has less things to do + m_values[i].destroy_unsafe(); + m_tags[i] = kTombstone; + } + // NOLINTEND(*-pointer-arithmetic) + } + + ASL_ASSERT(new_size == m_size); + + m_size = 0; + destroy(); + + m_tags = new_tags; + m_values = new_values; + m_capacity = new_capacity; + m_size = new_size; + } + + void clear_values() + { + if constexpr (!trivially_destructible<T>) + { + if (m_size > 0) + { + for (isize_t i = 0; i < m_capacity; ++i) + { + if ((m_tags[i] & kHasValue) != 0) // NOLINT(*-pointer-arithmetic) + { + m_values[i].destroy_unsafe(); // NOLINT(*-pointer-arithmetic) + } + } + } + } + } + + void copy_from(const hash_set& other) + { + if (other.size() > 0) + { + isize_t min_capacity = size_to_capacity(other.size()); + if (m_capacity < min_capacity) + { + grow_and_rehash(min_capacity); + } + ASL_ASSERT(m_capacity >= min_capacity); + + for (isize_t i = 0; i < other.m_capacity; ++i) + { + if ((other.m_tags[i] & kHasValue) != 0) // NOLINT(*-pointer-arithmetic) + { + insert(other.m_values[i].as_init_unsafe()); // NOLINT(*-pointer-arithmetic) + } + } + } + } + + struct FindSlotResult + { + uint8_t tag{}; + isize_t first_available_index = -1; + isize_t already_present_index = -1; + }; + + template<typename U> + requires key_hasher<KeyHasher, U> && key_comparator<KeyComparator, T, U> + static FindSlotResult find_slot_insert( + const U& value, + const uint8_t* tags, + const maybe_uninit<T>* values, + isize_t capacity) + { + ASL_ASSERT(is_pow2(capacity)); + + FindSlotResult result{}; + + const isize_t capacity_mask = capacity - 1; + const uint64_t hash = KeyHasher::hash(value); + const auto starting_index = static_cast<isize_t>(hash >> 7) & capacity_mask; + + result.tag = static_cast<uint8_t>(hash & kHashMask) | kHasValue; + + // NOLINTBEGIN(*-pointer-arithmetic) + + for ( + isize_t i = starting_index; + i != starting_index || result.first_available_index < 0; + i = (i + 1) & capacity_mask) + { + uint8_t t = tags[i]; + + if ((t & kHasValue) == 0 && result.first_available_index < 0) + { + result.first_available_index = i; + } + + if (t == result.tag && KeyComparator::eq(values[i].as_init_unsafe(), value)) + { + ASL_ASSERT(result.already_present_index < 0); + result.already_present_index = i; + if (result.first_available_index < 0) + { + result.first_available_index = i; + } + break; + } + + if (t == kEmpty) { break; } + } + + // NOLINTEND(*-pointer-arithmetic) + + return result; + } + + template<typename U> + requires key_hasher<KeyHasher, U> && key_comparator<KeyComparator, T, U> + isize_t find_slot_lookup(const U& value) const + { + if (m_size <= 0) { return -1; }; + + ASL_ASSERT(is_pow2(m_capacity)); + + const isize_t capacity_mask = m_capacity - 1; + const uint64_t hash = KeyHasher::hash(value); + const uint8_t tag = static_cast<uint8_t>(hash & kHashMask) | kHasValue; + const auto starting_index = static_cast<isize_t>(hash >> 7) & capacity_mask; + + // NOLINTBEGIN(*-pointer-arithmetic) + + isize_t i = starting_index; + do + { + const uint8_t t = m_tags[i]; + + if (t == tag && KeyComparator::eq(m_values[i].as_init_unsafe(), value)) { return i; } + if (t == kEmpty) { break; } + + i = (i + 1) & capacity_mask; + } while (i != starting_index); + + // NOLINTEND(*-pointer-arithmetic) + + return -1; + } + + template<typename U> + requires key_hasher<KeyHasher, U> && key_comparator<KeyComparator, T, U> + FindSlotResult find_slot_insert(const U& value) + { + return find_slot_insert(value, m_tags, m_values, m_capacity); + } + + void maybe_grow_to_fit_one_more() + { + if (m_size >= max_size()) + { + grow_and_rehash(); + } + } + +public: + constexpr hash_set() requires default_constructible<Allocator> + : m_allocator{} + {} + + explicit constexpr hash_set(Allocator allocator) + : m_allocator{ASL_MOVE(allocator)} + {} + + hash_set(const hash_set& other) + requires copy_constructible<Allocator> && copyable<T> + : hash_set{other.m_allocator} + { + copy_from(other); + } + + hash_set& operator=(const hash_set& other) + requires copyable<T> + { + if (&other != this) + { + clear(); + copy_from(other); + } + return *this; + } + + hash_set(hash_set&& other) + requires move_constructible<Allocator> + : m_tags{exchange(other.m_tags, nullptr)} + , m_values{exchange(other.m_values, nullptr)} + , m_capacity{exchange(other.m_capacity, 0)} + , m_size{exchange(other.m_size, 0)} + , m_allocator{ASL_MOVE(other.m_allocator)} + {} + + hash_set& operator=(hash_set&& other) + { + if (&other != this) + { + destroy(); + m_tags = exchange(other.m_tags, nullptr); + m_values = exchange(other.m_values, nullptr); + m_capacity = exchange(other.m_capacity, 0); + m_size = exchange(other.m_size, 0); + m_allocator = ASL_MOVE(other.m_allocator); + } + return *this; + } + + ~hash_set() + { + destroy(); + } + + void destroy() + { + clear_values(); + m_size = 0; + + if (m_capacity > 0) + { + m_allocator.dealloc(m_tags, layout::array<uint8_t>(m_capacity)); + m_allocator.dealloc(m_values, layout::array<maybe_uninit<T>>(m_capacity)); + m_capacity = 0; + } + } + + void clear() + { + clear_values(); + m_size = 0; + + if (m_capacity > 0) + { + asl::memzero(m_tags, m_capacity); + } + } + + constexpr isize_t size() const { return m_size; } + + template<typename... Args> + void insert(Args&&... args) + requires constructible_from<T, Args&&...> + { + maybe_grow_to_fit_one_more(); + ASL_ASSERT(m_size < max_size()); + insert_inner(ASL_MOVE(T{ASL_FWD(args)...}), m_tags, m_values, m_capacity, &m_size); + } + + template<typename U> + requires key_hasher<KeyHasher, U> && key_comparator<KeyComparator, T, U> + bool contains(const U& value) const + { + return find_slot_lookup(value) >= 0; + } + + template<typename U> + requires key_hasher<KeyHasher, U> && key_comparator<KeyComparator, T, U> + bool remove(const U& value) + { + isize_t slot = find_slot_lookup(value); + if (slot < 0) { return false; } + + m_values[slot].destroy_unsafe(); // NOLINT(*-pointer-arithmetic) + m_tags[slot] = kTombstone; // NOLINT(*-pointer-arithmetic) + m_size -= 1; + + return true; + } +}; + +} // namespace asl + |