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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef __BLI_SET_H__
#define __BLI_SET_H__
/** \file
* \ingroup bli
*
* This file provides a set implementation that uses open addressing with probing.
*/
#include "BLI_hash_cxx.h"
#include "BLI_open_addressing.h"
#include "BLI_vector.h"
namespace BLI {
// clang-format off
#define ITER_SLOTS_BEGIN(VALUE, ARRAY, OPTIONAL_CONST, R_ITEM, R_OFFSET) \
uint32_t hash = DefaultHash<T>{}(VALUE); \
uint32_t perturb = hash; \
while (true) { \
uint32_t item_index = (hash & ARRAY.slot_mask()) >> OFFSET_SHIFT; \
uint8_t R_OFFSET = hash & OFFSET_MASK; \
uint8_t initial_offset = R_OFFSET; \
OPTIONAL_CONST Item &R_ITEM = ARRAY.item(item_index); \
do {
#define ITER_SLOTS_END(R_OFFSET) \
R_OFFSET = (R_OFFSET + 1) & OFFSET_MASK; \
} while (R_OFFSET != initial_offset); \
perturb >>= 5; \
hash = hash * 5 + 1 + perturb; \
} ((void)0)
// clang-format on
template<typename T, typename Allocator = GuardedAllocator> class Set {
private:
static constexpr uint OFFSET_MASK = 3;
static constexpr uint OFFSET_SHIFT = 2;
class Item {
private:
static constexpr uint8_t IS_EMPTY = 0;
static constexpr uint8_t IS_SET = 1;
static constexpr uint8_t IS_DUMMY = 2;
uint8_t m_status[4];
char m_values[4 * sizeof(T)];
public:
static constexpr uint slots_per_item = 4;
Item()
{
for (uint offset = 0; offset < 4; offset++) {
m_status[offset] = IS_EMPTY;
}
}
~Item()
{
for (uint offset = 0; offset < 4; offset++) {
if (m_status[offset] == IS_SET) {
destruct(this->value(offset));
}
}
}
Item(const Item &other)
{
for (uint offset = 0; offset < 4; offset++) {
uint8_t status = other.m_status[offset];
m_status[offset] = status;
if (status == IS_SET) {
T *src = other.value(offset);
T *dst = this->value(offset);
new (dst) T(*src);
}
}
}
Item(Item &&other) noexcept
{
for (uint offset = 0; offset < 4; offset++) {
uint8_t status = other.m_status[offset];
m_status[offset] = status;
if (status == IS_SET) {
T *src = other.value(offset);
T *dst = this->value(offset);
new (dst) T(std::move(*src));
}
}
}
Item &operator=(const Item &other) = delete;
Item &operator=(Item &&other) = delete;
T *value(uint offset) const
{
return (T *)(m_values + offset * sizeof(T));
}
void copy_in(uint offset, const T &value)
{
BLI_assert(m_status[offset] != IS_SET);
m_status[offset] = IS_SET;
T *dst = this->value(offset);
new (dst) T(value);
}
void move_in(uint offset, T &value)
{
BLI_assert(m_status[offset] != IS_SET);
m_status[offset] = IS_SET;
T *dst = this->value(offset);
new (dst) T(std::move(value));
}
void set_dummy(uint offset)
{
BLI_assert(m_status[offset] == IS_SET);
m_status[offset] = IS_DUMMY;
destruct(this->value(offset));
}
bool is_empty(uint offset) const
{
return m_status[offset] == IS_EMPTY;
}
bool is_set(uint offset) const
{
return m_status[offset] == IS_SET;
}
bool is_dummy(uint offset) const
{
return m_status[offset] == IS_DUMMY;
}
bool has_value(uint offset, const T &value) const
{
return m_status[offset] == IS_SET && *this->value(offset) == value;
}
};
using ArrayType = OpenAddressingArray<Item, 1, Allocator>;
ArrayType m_array = OpenAddressingArray<Item>();
public:
Set() = default;
/**
* Create a new set that contains the given elements.
*/
Set(ArrayRef<T> values)
{
this->reserve(values.size());
for (const T &value : values) {
this->add(value);
}
}
/**
* Create a new set from an initializer list.
*/
Set(std::initializer_list<T> values) : Set(ArrayRef<T>(values))
{
}
/**
* Make the set large enough to hold the given amount of elements.
*/
void reserve(uint32_t min_usable_slots)
{
if (m_array.slots_usable() < min_usable_slots) {
this->grow(min_usable_slots);
}
}
/**
* Add a new element to the set.
* Asserts that the element did not exist in the set before.
*/
void add_new(const T &value)
{
BLI_assert(!this->contains(value));
this->ensure_can_add();
ITER_SLOTS_BEGIN (value, m_array, , item, offset) {
if (item.is_empty(offset)) {
item.copy_in(offset, value);
m_array.update__empty_to_set();
return;
}
}
ITER_SLOTS_END(offset);
}
/**
* Add a new value to the set if it does not exist yet.
*/
bool add(const T &value)
{
this->ensure_can_add();
ITER_SLOTS_BEGIN (value, m_array, , item, offset) {
if (item.is_empty(offset)) {
item.copy_in(offset, value);
m_array.update__empty_to_set();
return true;
}
else if (item.has_value(offset, value)) {
return false;
}
}
ITER_SLOTS_END(offset);
}
/**
* Add multiple elements to the set.
*/
void add_multiple(ArrayRef<T> values)
{
for (const T &value : values) {
this->add(value);
}
}
/**
* Add multiple new elements to the set.
* Asserts that none of the elements existed in the set before.
*/
void add_multiple_new(ArrayRef<T> values)
{
for (const T &value : values) {
this->add_new(value);
}
}
/**
* Returns true when the value is in the set, otherwise false.
*/
bool contains(const T &value) const
{
ITER_SLOTS_BEGIN (value, m_array, const, item, offset) {
if (item.is_empty(offset)) {
return false;
}
else if (item.has_value(offset, value)) {
return true;
}
}
ITER_SLOTS_END(offset);
}
/**
* Remove the value from the set.
* Asserts that the value exists in the set currently.
*/
void remove(const T &value)
{
BLI_assert(this->contains(value));
ITER_SLOTS_BEGIN (value, m_array, , item, offset) {
if (item.has_value(offset, value)) {
item.set_dummy(offset);
m_array.update__set_to_dummy();
return;
}
}
ITER_SLOTS_END(offset);
}
Vector<T> to_small_vector() const
{
Vector<T> vector;
vector.reserve(this->size());
for (const T &value : *this) {
vector.append(value);
}
return vector;
}
uint32_t size() const
{
return m_array.slots_set();
}
/**
* Returns true when there is at least one element that is in both sets.
* Otherwise false.
*/
static bool Intersects(const Set &a, const Set &b)
{
/* Make sure we iterate over the shorter set. */
if (a.size() > b.size()) {
return Intersects(b, a);
}
for (const T &value : a) {
if (b.contains(value)) {
return true;
}
}
return false;
}
/**
* Returns true when there is no value that is in both sets.
* Otherwise false.
*/
static bool Disjoint(const Set &a, const Set &b)
{
return !Intersects(a, b);
}
void print_table() const
{
std::cout << "Hash Table:\n";
std::cout << " Size: " << m_array.slots_set() << '\n';
std::cout << " Capacity: " << m_array.slots_total() << '\n';
uint32_t item_index = 0;
for (const Item &item : m_array) {
std::cout << " Item: " << item_index++ << '\n';
for (uint offset = 0; offset < 4; offset++) {
std::cout << " " << offset << " \t";
if (item.is_empty(offset)) {
std::cout << " <empty>\n";
}
else if (item.is_set(offset)) {
const T &value = *item.value(offset);
uint32_t collisions = this->count_collisions(value);
std::cout << " " << value << " \t Collisions: " << collisions << '\n';
}
else if (item.is_dummy(offset)) {
std::cout << " <dummy>\n";
}
}
}
}
class Iterator {
private:
const Set *m_set;
uint32_t m_slot;
public:
Iterator(const Set *set, uint32_t slot) : m_set(set), m_slot(slot)
{
}
Iterator &operator++()
{
m_slot = m_set->next_slot(m_slot + 1);
return *this;
}
const T &operator*() const
{
uint32_t item_index = m_slot >> OFFSET_SHIFT;
uint offset = m_slot & OFFSET_MASK;
const Item &item = m_set->m_array.item(item_index);
BLI_assert(item.is_set(offset));
return *item.value(offset);
}
friend bool operator==(const Iterator &a, const Iterator &b)
{
BLI_assert(a.m_set == b.m_set);
return a.m_slot == b.m_slot;
}
friend bool operator!=(const Iterator &a, const Iterator &b)
{
return !(a == b);
}
};
friend Iterator;
Iterator begin() const
{
return Iterator(this, this->next_slot(0));
}
Iterator end() const
{
return Iterator(this, m_array.slots_total());
}
private:
uint32_t next_slot(uint32_t slot) const
{
for (; slot < m_array.slots_total(); slot++) {
uint32_t item_index = slot >> OFFSET_SHIFT;
uint offset = slot & OFFSET_MASK;
const Item &item = m_array.item(item_index);
if (item.is_set(offset)) {
return slot;
}
}
return slot;
}
void ensure_can_add()
{
if (UNLIKELY(m_array.should_grow())) {
this->grow(this->size() + 1);
}
}
BLI_NOINLINE void grow(uint32_t min_usable_slots)
{
ArrayType new_array = m_array.init_reserved(min_usable_slots);
for (Item &old_item : m_array) {
for (uint8_t offset = 0; offset < 4; offset++) {
if (old_item.is_set(offset)) {
this->add_after_grow(*old_item.value(offset), new_array);
}
}
}
m_array = std::move(new_array);
}
void add_after_grow(T &old_value, ArrayType &new_array)
{
ITER_SLOTS_BEGIN (old_value, new_array, , item, offset) {
if (item.is_empty(offset)) {
item.move_in(offset, old_value);
return;
}
}
ITER_SLOTS_END(offset);
}
uint32_t count_collisions(const T &value) const
{
uint32_t collisions = 0;
ITER_SLOTS_BEGIN (value, m_array, const, item, offset) {
if (item.is_empty(offset) || item.has_value(offset, value)) {
return collisions;
}
collisions++;
}
ITER_SLOTS_END(offset);
}
};
#undef ITER_SLOTS_BEGIN
#undef ITER_SLOTS_END
} // namespace BLI
#endif /* __BLI_SET_H__ */
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