godot/core/templates/hash_set.h

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/*  hash_set.h                                                            */
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#ifndef HASH_SET_H
#define HASH_SET_H

#include "core/math/math_funcs.h"
#include "core/os/memory.h"
#include "core/templates/hash_map.h"
#include "core/templates/hashfuncs.h"
#include "core/templates/paged_allocator.h"

/**
 * 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 { … }

	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) { … }

	bool _lookup_pos(const TKey &p_key, uint32_t &r_pos) const { … }

	uint32_t _insert_with_hash(uint32_t p_hash, uint32_t p_index) { … }

	void _resize_and_rehash(uint32_t p_new_capacity_index) { … }

	_FORCE_INLINE_ int32_t _insert(const TKey &p_key) { … }

	void _init_from(const HashSet &p_other) { … }

public:
	_FORCE_INLINE_ uint32_t get_capacity() const { … }
	_FORCE_INLINE_ uint32_t size() const { … }

	/* Standard Godot Container API */

	bool is_empty() const { … }

	void clear() { … }

	_FORCE_INLINE_ bool has(const TKey &p_key) const { … }

	bool erase(const TKey &p_key) { … }

	// 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) { … }

	/** 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 { … }
	_FORCE_INLINE_ Iterator end() const { … }
	_FORCE_INLINE_ Iterator last() const { … }

	_FORCE_INLINE_ Iterator find(const TKey &p_key) const { … }

	_FORCE_INLINE_ void remove(const Iterator &p_iter) { … }

	/* Insert */

	Iterator insert(const TKey &p_key) { … }

	/* Constructors */

	HashSet(const HashSet &p_other) { … }

	void operator=(const HashSet &p_other) { … }

	HashSet(uint32_t p_initial_capacity) { … }
	HashSet() { … }

	void reset() { … }

	~HashSet() { … }
};

#endif // HASH_SET_H