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477 lines
14 KiB
C++
477 lines
14 KiB
C++
/*************************************************************************/
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/* hash_set.h */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md). */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#ifndef HASH_SET_H
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#define HASH_SET_H
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#include "core/math/math_funcs.h"
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#include "core/os/memory.h"
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#include "core/templates/hash_map.h"
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#include "core/templates/hashfuncs.h"
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#include "core/templates/paged_allocator.h"
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/**
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* Implementation of Set using a bidi indexed hash map.
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* Use RBSet instead of this only if the following conditions are met:
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*
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* - You need to keep an iterator or const pointer to Key and you intend to add/remove elements in the meantime.
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* - Iteration order does matter (via operator<)
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*
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*/
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template <class TKey,
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class Hasher = HashMapHasherDefault,
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class Comparator = HashMapComparatorDefault<TKey>>
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class HashSet {
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public:
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static constexpr uint32_t MIN_CAPACITY_INDEX = 2; // Use a prime.
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static constexpr float MAX_OCCUPANCY = 0.75;
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static constexpr uint32_t EMPTY_HASH = 0;
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private:
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TKey *keys = nullptr;
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uint32_t *hash_to_key = nullptr;
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uint32_t *key_to_hash = nullptr;
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uint32_t *hashes = nullptr;
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uint32_t capacity_index = 0;
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uint32_t num_elements = 0;
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_FORCE_INLINE_ uint32_t _hash(const TKey &p_key) const {
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uint32_t hash = Hasher::hash(p_key);
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if (unlikely(hash == EMPTY_HASH)) {
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hash = EMPTY_HASH + 1;
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}
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return hash;
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}
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static _FORCE_INLINE_ uint32_t _get_probe_length(const uint32_t p_pos, const uint32_t p_hash, const uint32_t p_capacity, const uint64_t p_capacity_inv) {
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const uint32_t original_pos = fastmod(p_hash, p_capacity_inv, p_capacity);
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return fastmod(p_pos - original_pos + p_capacity, p_capacity_inv, p_capacity);
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}
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bool _lookup_pos(const TKey &p_key, uint32_t &r_pos) const {
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if (keys == nullptr) {
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return false; // Failed lookups, no elements
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}
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const uint32_t capacity = hash_table_size_primes[capacity_index];
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const uint64_t capacity_inv = hash_table_size_primes_inv[capacity_index];
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uint32_t hash = _hash(p_key);
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uint32_t pos = fastmod(hash, capacity_inv, capacity);
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uint32_t distance = 0;
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while (true) {
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if (hashes[pos] == EMPTY_HASH) {
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return false;
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}
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if (distance > _get_probe_length(pos, hashes[pos], capacity, capacity_inv)) {
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return false;
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}
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if (hashes[pos] == hash && Comparator::compare(keys[hash_to_key[pos]], p_key)) {
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r_pos = hash_to_key[pos];
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return true;
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}
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pos = fastmod(pos + 1, capacity_inv, capacity);
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distance++;
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}
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}
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uint32_t _insert_with_hash(uint32_t p_hash, uint32_t p_index) {
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const uint32_t capacity = hash_table_size_primes[capacity_index];
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const uint64_t capacity_inv = hash_table_size_primes_inv[capacity_index];
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uint32_t hash = p_hash;
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uint32_t index = p_index;
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uint32_t distance = 0;
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uint32_t pos = fastmod(hash, capacity_inv, capacity);
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while (true) {
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if (hashes[pos] == EMPTY_HASH) {
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hashes[pos] = hash;
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key_to_hash[index] = pos;
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hash_to_key[pos] = index;
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return pos;
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}
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// Not an empty slot, let's check the probing length of the existing one.
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uint32_t existing_probe_len = _get_probe_length(pos, hashes[pos], capacity, capacity_inv);
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if (existing_probe_len < distance) {
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key_to_hash[index] = pos;
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SWAP(hash, hashes[pos]);
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SWAP(index, hash_to_key[pos]);
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distance = existing_probe_len;
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}
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pos = fastmod(pos + 1, capacity_inv, capacity);
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distance++;
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}
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}
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void _resize_and_rehash(uint32_t p_new_capacity_index) {
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// Capacity can't be 0.
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capacity_index = MAX((uint32_t)MIN_CAPACITY_INDEX, p_new_capacity_index);
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uint32_t capacity = hash_table_size_primes[capacity_index];
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uint32_t *old_hashes = hashes;
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uint32_t *old_key_to_hash = key_to_hash;
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hashes = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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keys = reinterpret_cast<TKey *>(Memory::realloc_static(keys, sizeof(TKey) * capacity));
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key_to_hash = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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hash_to_key = reinterpret_cast<uint32_t *>(Memory::realloc_static(hash_to_key, sizeof(uint32_t) * capacity));
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for (uint32_t i = 0; i < capacity; i++) {
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hashes[i] = EMPTY_HASH;
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}
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for (uint32_t i = 0; i < num_elements; i++) {
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uint32_t h = old_hashes[old_key_to_hash[i]];
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_insert_with_hash(h, i);
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}
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Memory::free_static(old_hashes);
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Memory::free_static(old_key_to_hash);
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}
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_FORCE_INLINE_ int32_t _insert(const TKey &p_key) {
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uint32_t capacity = hash_table_size_primes[capacity_index];
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if (unlikely(keys == nullptr)) {
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// Allocate on demand to save memory.
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hashes = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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keys = reinterpret_cast<TKey *>(Memory::alloc_static(sizeof(TKey) * capacity));
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key_to_hash = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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hash_to_key = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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for (uint32_t i = 0; i < capacity; i++) {
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hashes[i] = EMPTY_HASH;
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}
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}
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uint32_t pos = 0;
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bool exists = _lookup_pos(p_key, pos);
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if (exists) {
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return pos;
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} else {
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if (num_elements + 1 > MAX_OCCUPANCY * capacity) {
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ERR_FAIL_COND_V_MSG(capacity_index + 1 == HASH_TABLE_SIZE_MAX, -1, "Hash table maximum capacity reached, aborting insertion.");
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_resize_and_rehash(capacity_index + 1);
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}
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uint32_t hash = _hash(p_key);
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memnew_placement(&keys[num_elements], TKey(p_key));
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_insert_with_hash(hash, num_elements);
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num_elements++;
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return num_elements - 1;
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}
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}
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void _init_from(const HashSet &p_other) {
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capacity_index = p_other.capacity_index;
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num_elements = p_other.num_elements;
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if (p_other.num_elements == 0) {
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return;
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}
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uint32_t capacity = hash_table_size_primes[capacity_index];
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hashes = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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keys = reinterpret_cast<TKey *>(Memory::alloc_static(sizeof(TKey) * capacity));
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key_to_hash = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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hash_to_key = reinterpret_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
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for (uint32_t i = 0; i < num_elements; i++) {
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memnew_placement(&keys[i], TKey(p_other.keys[i]));
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key_to_hash[i] = p_other.key_to_hash[i];
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}
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for (uint32_t i = 0; i < capacity; i++) {
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hashes[i] = p_other.hashes[i];
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hash_to_key[i] = p_other.hash_to_key[i];
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}
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}
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public:
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_FORCE_INLINE_ uint32_t get_capacity() const { return hash_table_size_primes[capacity_index]; }
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_FORCE_INLINE_ uint32_t size() const { return num_elements; }
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/* Standard Godot Container API */
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bool is_empty() const {
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return num_elements == 0;
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}
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void clear() {
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if (keys == nullptr) {
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return;
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}
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uint32_t capacity = hash_table_size_primes[capacity_index];
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for (uint32_t i = 0; i < capacity; i++) {
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hashes[i] = EMPTY_HASH;
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}
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for (uint32_t i = 0; i < num_elements; i++) {
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keys[i].~TKey();
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}
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num_elements = 0;
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}
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_FORCE_INLINE_ bool has(const TKey &p_key) const {
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uint32_t _pos = 0;
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return _lookup_pos(p_key, _pos);
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}
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bool erase(const TKey &p_key) {
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uint32_t pos = 0;
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bool exists = _lookup_pos(p_key, pos);
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if (!exists) {
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return false;
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}
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uint32_t key_pos = pos;
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pos = key_to_hash[pos]; //make hash pos
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const uint32_t capacity = hash_table_size_primes[capacity_index];
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const uint64_t capacity_inv = hash_table_size_primes_inv[capacity_index];
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uint32_t next_pos = fastmod(pos + 1, capacity_inv, capacity);
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while (hashes[next_pos] != EMPTY_HASH && _get_probe_length(next_pos, hashes[next_pos], capacity, capacity_inv) != 0) {
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uint32_t kpos = hash_to_key[pos];
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uint32_t kpos_next = hash_to_key[next_pos];
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SWAP(key_to_hash[kpos], key_to_hash[kpos_next]);
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SWAP(hashes[next_pos], hashes[pos]);
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SWAP(hash_to_key[next_pos], hash_to_key[pos]);
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pos = next_pos;
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next_pos = fastmod(pos + 1, capacity_inv, capacity);
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}
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hashes[pos] = EMPTY_HASH;
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keys[key_pos].~TKey();
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num_elements--;
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if (key_pos < num_elements) {
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// Not the last key, move the last one here to keep keys lineal
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memnew_placement(&keys[key_pos], TKey(keys[num_elements]));
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keys[num_elements].~TKey();
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key_to_hash[key_pos] = key_to_hash[num_elements];
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hash_to_key[key_to_hash[num_elements]] = key_pos;
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}
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return true;
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}
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// Reserves space for a number of elements, useful to avoid many resizes and rehashes.
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// If adding a known (possibly large) number of elements at once, must be larger than old capacity.
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void reserve(uint32_t p_new_capacity) {
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uint32_t new_index = capacity_index;
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while (hash_table_size_primes[new_index] < p_new_capacity) {
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ERR_FAIL_COND_MSG(new_index + 1 == (uint32_t)HASH_TABLE_SIZE_MAX, nullptr);
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new_index++;
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}
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if (new_index == capacity_index) {
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return;
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}
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if (keys == nullptr) {
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capacity_index = new_index;
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return; // Unallocated yet.
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}
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_resize_and_rehash(new_index);
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}
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/** Iterator API **/
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struct Iterator {
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_FORCE_INLINE_ const TKey &operator*() const {
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return keys[index];
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}
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_FORCE_INLINE_ const TKey *operator->() const {
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return &keys[index];
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}
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_FORCE_INLINE_ Iterator &operator++() {
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index++;
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if (index >= (int32_t)num_keys) {
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index = -1;
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keys = nullptr;
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num_keys = 0;
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}
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return *this;
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}
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_FORCE_INLINE_ Iterator &operator--() {
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index--;
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if (index < 0) {
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index = -1;
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keys = nullptr;
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num_keys = 0;
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}
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return *this;
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}
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_FORCE_INLINE_ bool operator==(const Iterator &b) const { return keys == b.keys && index == b.index; }
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_FORCE_INLINE_ bool operator!=(const Iterator &b) const { return keys != b.keys || index != b.index; }
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_FORCE_INLINE_ explicit operator bool() const {
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return keys != nullptr;
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}
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_FORCE_INLINE_ Iterator(const TKey *p_keys, uint32_t p_num_keys, int32_t p_index = -1) {
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keys = p_keys;
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num_keys = p_num_keys;
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index = p_index;
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}
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_FORCE_INLINE_ Iterator() {}
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_FORCE_INLINE_ Iterator(const Iterator &p_it) {
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keys = p_it.keys;
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num_keys = p_it.num_keys;
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index = p_it.index;
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}
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_FORCE_INLINE_ void operator=(const Iterator &p_it) {
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keys = p_it.keys;
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num_keys = p_it.num_keys;
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index = p_it.index;
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}
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private:
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const TKey *keys = nullptr;
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uint32_t num_keys = 0;
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int32_t index = -1;
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};
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_FORCE_INLINE_ Iterator begin() const {
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return num_elements ? Iterator(keys, num_elements, 0) : Iterator();
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}
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_FORCE_INLINE_ Iterator end() const {
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return Iterator();
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}
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_FORCE_INLINE_ Iterator last() const {
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if (num_elements == 0) {
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return Iterator();
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}
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return Iterator(keys, num_elements, num_elements - 1);
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}
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_FORCE_INLINE_ Iterator find(const TKey &p_key) const {
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uint32_t pos = 0;
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bool exists = _lookup_pos(p_key, pos);
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if (!exists) {
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return end();
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}
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return Iterator(keys, num_elements, pos);
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}
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_FORCE_INLINE_ void remove(const Iterator &p_iter) {
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if (p_iter) {
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erase(*p_iter);
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}
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}
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/* Insert */
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Iterator insert(const TKey &p_key) {
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uint32_t pos = _insert(p_key);
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return Iterator(keys, num_elements, pos);
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}
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/* Constructors */
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HashSet(const HashSet &p_other) {
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_init_from(p_other);
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}
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void operator=(const HashSet &p_other) {
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if (this == &p_other) {
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return; // Ignore self assignment.
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}
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clear();
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if (keys != nullptr) {
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Memory::free_static(keys);
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Memory::free_static(key_to_hash);
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Memory::free_static(hash_to_key);
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Memory::free_static(hashes);
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keys = nullptr;
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hashes = nullptr;
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hash_to_key = nullptr;
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key_to_hash = nullptr;
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}
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_init_from(p_other);
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}
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HashSet(uint32_t p_initial_capacity) {
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// Capacity can't be 0.
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capacity_index = 0;
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reserve(p_initial_capacity);
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}
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HashSet() {
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capacity_index = MIN_CAPACITY_INDEX;
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}
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void reset() {
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clear();
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if (keys != nullptr) {
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Memory::free_static(keys);
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Memory::free_static(key_to_hash);
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Memory::free_static(hash_to_key);
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Memory::free_static(hashes);
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keys = nullptr;
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hashes = nullptr;
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hash_to_key = nullptr;
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key_to_hash = nullptr;
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}
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capacity_index = MIN_CAPACITY_INDEX;
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}
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~HashSet() {
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clear();
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if (keys != nullptr) {
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Memory::free_static(keys);
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Memory::free_static(key_to_hash);
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Memory::free_static(hash_to_key);
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Memory::free_static(hashes);
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}
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}
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};
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#endif // HASH_SET_H
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