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godot-cpp/include/godot_cpp/templates/hash_set.hpp

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