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godot/core/hash_map.h

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/*************************************************************************/
/* hash_map.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md). */
/* */
/* 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 HASH_MAP_H
#define HASH_MAP_H
#include "core/error_macros.h"
#include "core/hashfuncs.h"
#include "core/list.h"
#include "core/math/math_funcs.h"
#include "core/os/memory.h"
#include "core/ustring.h"
/**
* @class HashMap
* @author Juan Linietsky <reduzio@gmail.com>
*
* Implementation of a standard Hashing HashMap, for quick lookups of Data associated with a Key.
* The implementation provides hashers for the default types, if you need a special kind of hasher, provide
* your own.
* @param TKey Key, search is based on it, needs to be hasheable. It is unique in this container.
* @param TData Data, data associated with the key
* @param Hasher Hasher object, needs to provide a valid static hash function for TKey
* @param Comparator comparator object, needs to be able to safely compare two TKey values. It needs to ensure that x == x for any items inserted in the map. Bear in mind that nan != nan when implementing an equality check.
* @param MIN_HASH_TABLE_POWER Miminum size of the hash table, as a power of two. You rarely need to change this parameter.
* @param RELATIONSHIP Relationship at which the hash table is resized. if amount of elements is RELATIONSHIP
* times bigger than the hash table, table is resized to solve this condition. if RELATIONSHIP is zero, table is always MIN_HASH_TABLE_POWER.
*
*/
template <class TKey, class TData, class Hasher = HashMapHasherDefault, class Comparator = HashMapComparatorDefault<TKey>, uint8_t MIN_HASH_TABLE_POWER = 3, uint8_t RELATIONSHIP = 8>
class HashMap {
public:
struct Pair {
TKey key;
TData data;
Pair() {}
Pair(const TKey &p_key, const TData &p_data) :
key(p_key),
data(p_data) {
}
};
struct Element {
private:
friend class HashMap;
uint32_t hash;
Element *next = nullptr;
Element() {}
Pair pair;
public:
const TKey &key() const {
return pair.key;
}
TData &value() {
return pair.data;
}
const TData &value() const {
return pair.value();
}
};
private:
Element **hash_table = nullptr;
uint8_t hash_table_power = 0;
uint32_t elements = 0;
void make_hash_table() {
ERR_FAIL_COND(hash_table);
hash_table = memnew_arr(Element *, (1 << MIN_HASH_TABLE_POWER));
hash_table_power = MIN_HASH_TABLE_POWER;
elements = 0;
for (int i = 0; i < (1 << MIN_HASH_TABLE_POWER); i++) {
hash_table[i] = nullptr;
}
}
void erase_hash_table() {
ERR_FAIL_COND_MSG(elements, "Cannot erase hash table if there are still elements inside.");
memdelete_arr(hash_table);
hash_table = nullptr;
hash_table_power = 0;
elements = 0;
}
void check_hash_table() {
int new_hash_table_power = -1;
if ((int)elements > ((1 << hash_table_power) * RELATIONSHIP)) {
/* rehash up */
new_hash_table_power = hash_table_power + 1;
while ((int)elements > ((1 << new_hash_table_power) * RELATIONSHIP)) {
new_hash_table_power++;
}
} else if ((hash_table_power > (int)MIN_HASH_TABLE_POWER) && ((int)elements < ((1 << (hash_table_power - 1)) * RELATIONSHIP))) {
/* rehash down */
new_hash_table_power = hash_table_power - 1;
while ((int)elements < ((1 << (new_hash_table_power - 1)) * RELATIONSHIP)) {
new_hash_table_power--;
}
if (new_hash_table_power < (int)MIN_HASH_TABLE_POWER) {
new_hash_table_power = MIN_HASH_TABLE_POWER;
}
}
if (new_hash_table_power == -1) {
return;
}
Element **new_hash_table = memnew_arr(Element *, ((uint64_t)1 << new_hash_table_power));
ERR_FAIL_COND_MSG(!new_hash_table, "Out of memory.");
for (int i = 0; i < (1 << new_hash_table_power); i++) {
new_hash_table[i] = nullptr;
}
if (hash_table) {
for (int i = 0; i < (1 << hash_table_power); i++) {
while (hash_table[i]) {
Element *se = hash_table[i];
hash_table[i] = se->next;
int new_pos = se->hash & ((1 << new_hash_table_power) - 1);
se->next = new_hash_table[new_pos];
new_hash_table[new_pos] = se;
}
}
memdelete_arr(hash_table);
}
hash_table = new_hash_table;
hash_table_power = new_hash_table_power;
}
/* I want to have only one function.. */
_FORCE_INLINE_ const Element *get_element(const TKey &p_key) const {
uint32_t hash = Hasher::hash(p_key);
uint32_t index = hash & ((1 << hash_table_power) - 1);
Element *e = hash_table[index];
while (e) {
/* checking hash first avoids comparing key, which may take longer */
if (e->hash == hash && Comparator::compare(e->pair.key, p_key)) {
/* the pair exists in this hashtable, so just update data */
return e;
}
e = e->next;
}
return nullptr;
}
Element *create_element(const TKey &p_key) {
/* if element doesn't exist, create it */
Element *e = memnew(Element);
ERR_FAIL_COND_V_MSG(!e, nullptr, "Out of memory.");
uint32_t hash = Hasher::hash(p_key);
uint32_t index = hash & ((1 << hash_table_power) - 1);
e->next = hash_table[index];
e->hash = hash;
e->pair.key = p_key;
e->pair.data = TData();
hash_table[index] = e;
elements++;
return e;
}
void copy_from(const HashMap &p_t) {
if (&p_t == this) {
return; /* much less bother with that */
}
clear();
if (!p_t.hash_table || p_t.hash_table_power == 0) {
return; /* not copying from empty table */
}
hash_table = memnew_arr(Element *, (uint64_t)1 << p_t.hash_table_power);
hash_table_power = p_t.hash_table_power;
elements = p_t.elements;
for (int i = 0; i < (1 << p_t.hash_table_power); i++) {
hash_table[i] = nullptr;
const Element *e = p_t.hash_table[i];
while (e) {
Element *le = memnew(Element); /* local element */
*le = *e; /* copy data */
/* add to list and reassign pointers */
le->next = hash_table[i];
hash_table[i] = le;
e = e->next;
}
}
}
public:
Element *set(const TKey &p_key, const TData &p_data) {
return set(Pair(p_key, p_data));
}
Element *set(const Pair &p_pair) {
Element *e = nullptr;
if (!hash_table) {
make_hash_table(); // if no table, make one
} else {
e = const_cast<Element *>(get_element(p_pair.key));
}
/* if we made it up to here, the pair doesn't exist, create and assign */
if (!e) {
e = create_element(p_pair.key);
if (!e) {
return nullptr;
}
check_hash_table(); // perform mantenience routine
}
e->pair.data = p_pair.data;
return e;
}
bool has(const TKey &p_key) const {
return getptr(p_key) != nullptr;
}
/**
* Get a key from data, return a const reference.
* WARNING: this doesn't check errors, use either getptr and check nullptr, or check
* first with has(key)
*/
const TData &get(const TKey &p_key) const {
const TData *res = getptr(p_key);
CRASH_COND_MSG(!res, "Map key not found.");
return *res;
}
TData &get(const TKey &p_key) {
TData *res = getptr(p_key);
CRASH_COND_MSG(!res, "Map key not found.");
return *res;
}
/**
* Same as get, except it can return nullptr when item was not found.
* This is mainly used for speed purposes.
*/
_FORCE_INLINE_ TData *getptr(const TKey &p_key) {
if (unlikely(!hash_table)) {
return nullptr;
}
Element *e = const_cast<Element *>(get_element(p_key));
if (e) {
return &e->pair.data;
}
return nullptr;
}
_FORCE_INLINE_ const TData *getptr(const TKey &p_key) const {
if (unlikely(!hash_table)) {
return nullptr;
}
const Element *e = const_cast<Element *>(get_element(p_key));
if (e) {
return &e->pair.data;
}
return nullptr;
}
/**
* Same as get, except it can return nullptr when item was not found.
* This version is custom, will take a hash and a custom key (that should support operator==()
*/
template <class C>
_FORCE_INLINE_ TData *custom_getptr(C p_custom_key, uint32_t p_custom_hash) {
if (unlikely(!hash_table)) {
return nullptr;
}
uint32_t hash = p_custom_hash;
uint32_t index = hash & ((1 << hash_table_power) - 1);
Element *e = hash_table[index];
while (e) {
/* checking hash first avoids comparing key, which may take longer */
if (e->hash == hash && Comparator::compare(e->pair.key, p_custom_key)) {
/* the pair exists in this hashtable, so just update data */
return &e->pair.data;
}
e = e->next;
}
return nullptr;
}
template <class C>
_FORCE_INLINE_ const TData *custom_getptr(C p_custom_key, uint32_t p_custom_hash) const {
if (unlikely(!hash_table)) {
return nullptr;
}
uint32_t hash = p_custom_hash;
uint32_t index = hash & ((1 << hash_table_power) - 1);
const Element *e = hash_table[index];
while (e) {
/* checking hash first avoids comparing key, which may take longer */
if (e->hash == hash && Comparator::compare(e->pair.key, p_custom_key)) {
/* the pair exists in this hashtable, so just update data */
return &e->pair.data;
}
e = e->next;
}
return nullptr;
}
/**
* Erase an item, return true if erasing was successful
*/
bool erase(const TKey &p_key) {
if (unlikely(!hash_table)) {
return false;
}
uint32_t hash = Hasher::hash(p_key);
uint32_t index = hash & ((1 << hash_table_power) - 1);
Element *e = hash_table[index];
Element *p = nullptr;
while (e) {
/* checking hash first avoids comparing key, which may take longer */
if (e->hash == hash && Comparator::compare(e->pair.key, p_key)) {
if (p) {
p->next = e->next;
} else {
//begin of list
hash_table[index] = e->next;
}
memdelete(e);
elements--;
if (elements == 0) {
erase_hash_table();
} else {
check_hash_table();
}
return true;
}
p = e;
e = e->next;
}
return false;
}
inline const TData &operator[](const TKey &p_key) const { //constref
return get(p_key);
}
inline TData &operator[](const TKey &p_key) { //assignment
Element *e = nullptr;
if (!hash_table) {
make_hash_table(); // if no table, make one
} else {
e = const_cast<Element *>(get_element(p_key));
}
/* if we made it up to here, the pair doesn't exist, create */
if (!e) {
e = create_element(p_key);
CRASH_COND(!e);
check_hash_table(); // perform mantenience routine
}
return e->pair.data;
}
/**
* Get the next key to p_key, and the first key if p_key is null.
* Returns a pointer to the next key if found, nullptr otherwise.
* Adding/Removing elements while iterating will, of course, have unexpected results, don't do it.
*
* Example:
*
* const TKey *k=nullptr;
*
* while( (k=table.next(k)) ) {
*
* print( *k );
* }
*
*/
const TKey *next(const TKey *p_key) const {
if (unlikely(!hash_table)) {
return nullptr;
}
if (!p_key) { /* get the first key */
for (int i = 0; i < (1 << hash_table_power); i++) {
if (hash_table[i]) {
return &hash_table[i]->pair.key;
}
}
} else { /* get the next key */
const Element *e = get_element(*p_key);
ERR_FAIL_COND_V_MSG(!e, nullptr, "Invalid key supplied.");
if (e->next) {
/* if there is a "next" in the list, return that */
return &e->next->pair.key;
} else {
/* go to next elements */
uint32_t index = e->hash & ((1 << hash_table_power) - 1);
index++;
for (int i = index; i < (1 << hash_table_power); i++) {
if (hash_table[i]) {
return &hash_table[i]->pair.key;
}
}
}
/* nothing found, was at end */
}
return nullptr; /* nothing found */
}
inline unsigned int size() const {
return elements;
}
inline bool empty() const {
return elements == 0;
}
void clear() {
/* clean up */
if (hash_table) {
for (int i = 0; i < (1 << hash_table_power); i++) {
while (hash_table[i]) {
Element *e = hash_table[i];
hash_table[i] = e->next;
memdelete(e);
}
}
memdelete_arr(hash_table);
}
hash_table = nullptr;
hash_table_power = 0;
elements = 0;
}
void operator=(const HashMap &p_table) {
copy_from(p_table);
}
void get_key_list(List<TKey> *r_keys) const {
if (unlikely(!hash_table)) {
return;
}
for (int i = 0; i < (1 << hash_table_power); i++) {
Element *e = hash_table[i];
while (e) {
r_keys->push_back(e->pair.key);
e = e->next;
}
}
}
HashMap() {}
HashMap(const HashMap &p_table) {
copy_from(p_table);
}
~HashMap() {
clear();
}
};
#endif // HASH_MAP_H
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