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SqMod/vendor/POCO/Foundation/include/Poco/ordered_hash.h
Sandu Liviu Catalin 4a6bfc086c Major plugin refactor and cleanup. 
Switched to POCO library for unified platform/library interface.
Deprecated the external module API. It was creating more problems than solving.
Removed most built-in libraries in favor of system libraries for easier maintenance.
Cleaned and secured code with help from static analyzers.
2021-01-30 08:51:39 +02:00

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/**
* MIT License
*
* Copyright (c) 2017 Tessil
*
* 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 TSL_ORDERED_HASH_H
#define TSL_ORDERED_HASH_H
#include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <iterator>
#include <limits>
#include <memory>
#include <stdexcept>
#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>
/**
* Macros for compatibility with GCC 4.8
*/
#ifndef TSL_NO_CONTAINER_ERASE_CONST_ITERATOR
#if (defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 9))
#define TSL_NO_CONTAINER_ERASE_CONST_ITERATOR
#endif
#endif
#ifndef TSL_NO_CONTAINER_EMPLACE_CONST_ITERATOR
#if (defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 9))
#define TSL_NO_CONTAINER_EMPLACE_CONST_ITERATOR
#endif
#endif
/*
* Only activate tsl_assert if TSL_DEBUG is defined.
* This way we avoid the performance hit when NDEBUG is not defined with assert as tsl_assert is used a lot
* (people usually compile with "-O3" and not "-O3 -DNDEBUG").
*/
#ifndef tsl_assert
#ifdef TSL_DEBUG
#define tsl_assert(expr) assert(expr)
#else
#define tsl_assert(expr) (static_cast<void>(0))
#endif
#endif
namespace tsl {
namespace detail_ordered_hash {
template<typename T>
struct make_void {
using type = void;
};
template<typename T, typename = void>
struct has_is_transparent: std::false_type {
};
template<typename T>
struct has_is_transparent<T, typename make_void<typename T::is_transparent>::type>: std::true_type {
};
template<typename T, typename = void>
struct is_vector: std::false_type {
};
template<typename T>
struct is_vector<T, typename std::enable_if<
std::is_same<T, std::vector<typename T::value_type, typename T::allocator_type>>::value
>::type>: std::true_type {
};
/**
* Each bucket entry stores a 32-bits index which is the index in m_values corresponding to the bucket's value
* and a 32 bits hash (truncated if the original was 64-bits) corresponding to the hash of the value.
*
* The 32-bit index limits the size of the map to 2^32 - 1 elements (-1 due to a reserved value used to mark a
* bucket as empty).
*/
class bucket_entry {
public:
using index_type = std::uint_least32_t;
using truncated_hash_type = std::uint_least32_t;
bucket_entry() noexcept: m_index(EMPTY_MARKER_INDEX), m_hash(0) {
}
bool empty() const noexcept {
return m_index == EMPTY_MARKER_INDEX;
}
void clear() noexcept {
m_index = EMPTY_MARKER_INDEX;
}
index_type index() const noexcept {
tsl_assert(!empty());
return m_index;
}
index_type& index_ref() noexcept {
tsl_assert(!empty());
return m_index;
}
void set_index(index_type index) noexcept {
tsl_assert(index <= max_size());
m_index = index;
}
truncated_hash_type truncated_hash() const noexcept {
tsl_assert(!empty());
return m_hash;
}
truncated_hash_type& truncated_hash_ref() noexcept {
tsl_assert(!empty());
return m_hash;
}
void set_hash(std::size_t hash) noexcept {
m_hash = truncate_hash(hash);
}
static truncated_hash_type truncate_hash(std::size_t hash) noexcept {
return truncated_hash_type(hash);
}
static std::size_t max_size() noexcept {
return std::numeric_limits<index_type>::max() - NB_RESERVED_INDEXES;
}
private:
static const index_type EMPTY_MARKER_INDEX = std::numeric_limits<index_type>::max();
static const std::size_t NB_RESERVED_INDEXES = 1;
index_type m_index;
truncated_hash_type m_hash;
};
/**
* Internal common class used by ordered_map and ordered_set.
*
* ValueType is what will be stored by ordered_hash (usually std::pair<Key, T> for map and Key for set).
*
* KeySelect should be a FunctionObject which takes a ValueType in parameter and return a reference to the key.
*
* ValueSelect should be a FunctionObject which takes a ValueType in parameter and return a reference to the value.
* ValueSelect should be void if there is no value (in set for example).
*
* ValueTypeContainer is the container which will be used to store ValueType values.
* Usually a std::deque<ValueType, Allocator> or std::vector<ValueType, Allocator>.
*
*
*
* The orderd_hash structure is a hash table which preserves the order of insertion of the elements.
* To do so, it stores the values in the ValueTypeContainer (m_values) using emplace_back at each
* insertion of a new element. Another structure (m_buckets of type std::vector<bucket_entry>) will
* serve as buckets array for the hash table part. Each bucket stores an index which corresponds to
* the index in m_values where the bucket's value is and the (truncated) hash of this value. An index
* is used instead of a pointer to the value to reduce the size of each bucket entry.
*
* To resolve collisions in the buckets array, the structures use robin hood linear probing with
* backward shift deletion.
*/
template<class ValueType,
class KeySelect,
class ValueSelect,
class Hash,
class KeyEqual,
class Allocator,
class ValueTypeContainer>
class ordered_hash: private Hash, private KeyEqual {
private:
template<typename U>
using has_mapped_type = typename std::integral_constant<bool, !std::is_same<U, void>::value>;
static_assert(std::is_same<typename ValueTypeContainer::value_type, ValueType>::value,
"ValueTypeContainer::value_type != ValueType.");
static_assert(std::is_same<typename ValueTypeContainer::allocator_type, Allocator>::value,
"ValueTypeContainer::allocator_type != Allocator.");
public:
template<bool IsConst>
class ordered_iterator;
using key_type = typename KeySelect::key_type;
using value_type = ValueType;
using size_type = std::size_t;
using difference_type = std::ptrdiff_t;
using hasher = Hash;
using key_equal = KeyEqual;
using allocator_type = Allocator;
using reference = value_type&;
using const_reference = const value_type&;
using pointer = value_type*;
using const_pointer = const value_type*;
using iterator = ordered_iterator<false>;
using const_iterator = ordered_iterator<true>;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using values_container_type = ValueTypeContainer;
public:
template<bool IsConst>
class ordered_iterator {
friend class ordered_hash;
private:
using iterator = typename std::conditional<IsConst,
typename values_container_type::const_iterator,
typename values_container_type::iterator>::type;
ordered_iterator(iterator it) noexcept: m_iterator(it) {
}
public:
using iterator_category = std::random_access_iterator_tag;
using value_type = const typename ordered_hash::value_type;
using difference_type = typename iterator::difference_type;
using reference = value_type&;
using pointer = value_type*;
ordered_iterator() noexcept {
}
ordered_iterator(const ordered_iterator<false>& other) noexcept: m_iterator(other.m_iterator) {
}
const typename ordered_hash::key_type& key() const {
return KeySelect()(*m_iterator);
}
template<class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value && IsConst>::type* = nullptr>
const typename U::value_type& value() const {
return U()(*m_iterator);
}
template<class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value && !IsConst>::type* = nullptr>
typename U::value_type& value() {
return U()(*m_iterator);
}
reference operator*() const { return *m_iterator; }
pointer operator->() const { return m_iterator.operator->(); }
ordered_iterator& operator++() { ++m_iterator; return *this; }
ordered_iterator& operator--() { --m_iterator; return *this; }
ordered_iterator operator++(int) { ordered_iterator tmp(*this); ++(*this); return tmp; }
ordered_iterator operator--(int) { ordered_iterator tmp(*this); --(*this); return tmp; }
reference operator[](difference_type n) const { return m_iterator[n]; }
ordered_iterator& operator+=(difference_type n) { m_iterator += n; return *this; }
ordered_iterator& operator-=(difference_type n) { m_iterator -= n; return *this; }
ordered_iterator operator+(difference_type n) { ordered_iterator tmp(*this); tmp += n; return tmp; }
ordered_iterator operator-(difference_type n) { ordered_iterator tmp(*this); tmp -= n; return tmp; }
friend bool operator==(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator == rhs.m_iterator;
}
friend bool operator!=(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator != rhs.m_iterator;
}
friend bool operator<(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator < rhs.m_iterator;
}
friend bool operator>(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator > rhs.m_iterator;
}
friend bool operator<=(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator <= rhs.m_iterator;
}
friend bool operator>=(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator >= rhs.m_iterator;
}
friend ordered_iterator operator+(difference_type n, const ordered_iterator& it) {
return n + it.m_iterator;
}
friend difference_type operator-(const ordered_iterator& lhs, const ordered_iterator& rhs) {
return lhs.m_iterator - rhs.m_iterator;
}
private:
iterator m_iterator;
};
private:
using buckets_container_allocator = typename
std::allocator_traits<allocator_type>::template rebind_alloc<bucket_entry>;
using buckets_container_type = std::vector<bucket_entry, buckets_container_allocator>;
using truncated_hash_type = typename bucket_entry::truncated_hash_type;
using index_type = typename bucket_entry::index_type;
public:
ordered_hash(size_type bucket_count,
const Hash& hash,
const KeyEqual& equal,
const Allocator& alloc,
float max_load_factor): Hash(hash), KeyEqual(equal), m_buckets(alloc),
m_values(alloc), m_grow_on_next_insert(false)
{
bucket_count = round_up_to_power_of_two(bucket_count);
if(bucket_count > max_bucket_count()) {
throw std::length_error("The map exceeds its maxmimum size.");
}
tsl_assert(bucket_count > 0);
m_buckets.resize(bucket_count);
m_mask = bucket_count - 1;
this->max_load_factor(max_load_factor);
}
allocator_type get_allocator() const {
return m_values.get_allocator();
}
/*
* Iterators
*/
iterator begin() noexcept {
return iterator(m_values.begin());
}
const_iterator begin() const noexcept {
return cbegin();
}
const_iterator cbegin() const noexcept {
return const_iterator(m_values.cbegin());
}
iterator end() noexcept {
return iterator(m_values.end());
}
const_iterator end() const noexcept {
return cend();
}
const_iterator cend() const noexcept {
return const_iterator(m_values.cend());
}
reverse_iterator rbegin() noexcept {
return reverse_iterator(m_values.end());
}
const_reverse_iterator rbegin() const noexcept {
return rcbegin();
}
const_reverse_iterator rcbegin() const noexcept {
return const_reverse_iterator(m_values.cend());
}
reverse_iterator rend() noexcept {
return reverse_iterator(m_values.begin());
}
const_reverse_iterator rend() const noexcept {
return rcend();
}
const_reverse_iterator rcend() const noexcept {
return const_reverse_iterator(m_values.cbegin());
}
/*
* Capacity
*/
bool empty() const noexcept {
return m_values.empty();
}
size_type size() const noexcept {
return m_values.size();
}
size_type max_size() const noexcept {
return std::min(bucket_entry::max_size(), m_values.max_size());
}
/*
* Modifiers
*/
void clear() noexcept {
for(auto& bucket: m_buckets) {
bucket.clear();
}
m_values.clear();
m_grow_on_next_insert = false;
}
template<typename P>
std::pair<iterator, bool> insert(P&& value) {
return insert_impl(KeySelect()(value), std::forward<P>(value));
}
template<typename P>
iterator insert(const_iterator hint, P&& value) {
if(hint != cend() && compare_keys(KeySelect()(*hint), KeySelect()(value))) {
return mutable_iterator(hint);
}
return insert(std::forward<P>(value)).first;
}
template<class InputIt>
void insert(InputIt first, InputIt last) {
if(std::is_base_of<std::forward_iterator_tag,
typename std::iterator_traits<InputIt>::iterator_category>::value)
{
const auto nb_elements_insert = std::distance(first, last);
const size_type nb_free_buckets = m_load_threshold - size();
tsl_assert(m_load_threshold >= size());
if(nb_elements_insert > 0 && nb_free_buckets < size_type(nb_elements_insert)) {
reserve(size() + size_type(nb_elements_insert));
}
}
for(; first != last; ++first) {
insert(*first);
}
}
template<class K, class M>
std::pair<iterator, bool> insert_or_assign(K&& key, M&& value) {
auto it = try_emplace(std::forward<K>(key), std::forward<M>(value));
if(!it.second) {
it.first.value() = std::forward<M>(value);
}
return it;
}
template<class K, class M>
iterator insert_or_assign(const_iterator hint, K&& key, M&& obj) {
if(hint != cend() && compare_keys(KeySelect()(*hint), key)) {
auto it = mutable_iterator(hint);
it.value() = std::forward<M>(obj);
return it;
}
return insert_or_assign(std::forward<K>(key), std::forward<M>(obj)).first;
}
template<class... Args>
std::pair<iterator, bool> emplace(Args&&... args) {
return insert(value_type(std::forward<Args>(args)...));
}
template<class... Args>
iterator emplace_hint(const_iterator hint, Args&&... args) {
return insert(hint, value_type(std::forward<Args>(args)...));
}
template<class K, class... Args>
std::pair<iterator, bool> try_emplace(K&& key, Args&&... value_args) {
return insert_impl(key, std::piecewise_construct,
std::forward_as_tuple(std::forward<K>(key)),
std::forward_as_tuple(std::forward<Args>(value_args)...));
}
template<class K, class... Args>
iterator try_emplace(const_iterator hint, K&& key, Args&&... args) {
if(hint != cend() && compare_keys(KeySelect()(*hint), key)) {
return mutable_iterator(hint);
}
return try_emplace(std::forward<K>(key), std::forward<Args>(args)...).first;
}
/**
* Here to avoid `template<class K> size_type erase(const K& key)` being used when
* we use a iterator instead of a const_iterator.
*/
iterator erase(iterator pos) {
return erase(const_iterator(pos));
}
iterator erase(const_iterator pos) {
tsl_assert(pos != cend());
const std::size_t index_erase = iterator_to_index(pos);
auto it_bucket = find_key(pos.key(), hash_key(pos.key()));
tsl_assert(it_bucket != m_buckets.end());
erase_value_from_bucket(it_bucket);
/*
* One element was removed from m_values, due to the left shift the next element
* is now at the position of the previous element (or end if none).
*/
return begin() + index_erase;
}
iterator erase(const_iterator first, const_iterator last) {
if(first == last) {
return mutable_iterator(first);
}
tsl_assert(std::distance(first, last) > 0);
const std::size_t start_index = iterator_to_index(first);
const std::size_t nb_values = std::size_t(std::distance(first, last));
const std::size_t end_index = start_index + nb_values;
// Delete all values
#ifdef TSL_NO_CONTAINER_ERASE_CONST_ITERATOR
auto next_it = m_values.erase(mutable_iterator(first).m_iterator, mutable_iterator(last).m_iterator);
#else
auto next_it = m_values.erase(first.m_iterator, last.m_iterator);
#endif
/*
* Mark the buckets corresponding to the values as empty and do a backward shift.
*
* Also, the erase operation on m_values has shifted all the values on the right of last.m_iterator.
* Adapt the indexes for these values.
*/
std::size_t ibucket = 0;
while(ibucket < m_buckets.size()) {
if(m_buckets[ibucket].empty()) {
ibucket++;
}
else if(m_buckets[ibucket].index() >= start_index && m_buckets[ibucket].index() < end_index) {
m_buckets[ibucket].clear();
backward_shift(ibucket);
// Don't increment ibucket, backward_shift may have replaced current bucket.
}
else if(m_buckets[ibucket].index() >= end_index) {
m_buckets[ibucket].set_index(index_type(m_buckets[ibucket].index() - nb_values));
ibucket++;
}
else {
ibucket++;
}
}
return iterator(next_it);
}
template<class K>
size_type erase(const K& key) {
return erase(key, hash_key(key));
}
template<class K>
size_type erase(const K& key, std::size_t hash) {
return erase_impl(key, hash);
}
void swap(ordered_hash& other) {
using std::swap;
swap(static_cast<Hash&>(*this), static_cast<Hash&>(other));
swap(static_cast<KeyEqual&>(*this), static_cast<KeyEqual&>(other));
swap(m_buckets, other.m_buckets);
swap(m_mask, other.m_mask);
swap(m_values, other.m_values);
swap(m_grow_on_next_insert, other.m_grow_on_next_insert);
swap(m_max_load_factor, other.m_max_load_factor);
swap(m_load_threshold, other.m_load_threshold);
}
/*
* Lookup
*/
template<class K, class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value>::type* = nullptr>
typename U::value_type& at(const K& key) {
return at(key, hash_key(key));
}
template<class K, class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value>::type* = nullptr>
typename U::value_type& at(const K& key, std::size_t hash) {
return const_cast<typename U::value_type&>(static_cast<const ordered_hash*>(this)->at(key, hash));
}
template<class K, class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value>::type* = nullptr>
const typename U::value_type& at(const K& key) const {
return at(key, hash_key(key));
}
template<class K, class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value>::type* = nullptr>
const typename U::value_type& at(const K& key, std::size_t hash) const {
auto it = find(key, hash);
if(it != end()) {
return it.value();
}
else {
throw std::out_of_range("Couldn't find the key.");
}
}
template<class K, class U = ValueSelect, typename std::enable_if<has_mapped_type<U>::value>::type* = nullptr>
typename U::value_type& operator[](K&& key) {
return try_emplace(std::forward<K>(key)).first.value();
}
template<class K>
size_type count(const K& key) const {
return count(key, hash_key(key));
}
template<class K>
size_type count(const K& key, std::size_t hash) const {
if(find(key, hash) == cend()) {
return 0;
}
else {
return 1;
}
}
template<class K>
iterator find(const K& key) {
return find(key, hash_key(key));
}
template<class K>
iterator find(const K& key, std::size_t hash) {
auto it_bucket = find_key(key, hash);
return (it_bucket != m_buckets.end())?iterator(m_values.begin() + it_bucket->index()):end();
}
template<class K>
const_iterator find(const K& key) const {
return find(key, hash_key(key));
}
template<class K>
const_iterator find(const K& key, std::size_t hash) const {
auto it_bucket = find_key(key, hash);
return (it_bucket != m_buckets.cend())?const_iterator(m_values.begin() + it_bucket->index()):end();
}
template<class K>
std::pair<iterator, iterator> equal_range(const K& key) {
return equal_range(key, hash_key(key));
}
template<class K>
std::pair<iterator, iterator> equal_range(const K& key, std::size_t hash) {
iterator it = find(key, hash);
return std::make_pair(it, (it == end())?it:std::next(it));
}
template<class K>
std::pair<const_iterator, const_iterator> equal_range(const K& key) const {
return equal_range(key, hash_key(key));
}
template<class K>
std::pair<const_iterator, const_iterator> equal_range(const K& key, std::size_t hash) const {
const_iterator it = find(key, hash);
return std::make_pair(it, (it == cend())?it:std::next(it));
}
/*
* Bucket interface
*/
size_type bucket_count() const {
return m_buckets.size();
}
size_type max_bucket_count() const {
return m_buckets.max_size();
}
/*
* Hash policy
*/
float load_factor() const {
return float(size())/float(bucket_count());
}
float max_load_factor() const {
return m_max_load_factor;
}
void max_load_factor(float ml) {
m_max_load_factor = std::max(0.1f, std::min(ml, 0.95f));
m_load_threshold = size_type(float(bucket_count())*m_max_load_factor);
}
void rehash(size_type count) {
count = std::max(count, size_type(std::ceil(float(size())/max_load_factor())));
rehash_impl(count);
}
void reserve(size_type count) {
reserve_space_for_values(count);
count = size_type(std::ceil(float(count)/max_load_factor()));
rehash(count);
}
/*
* Observers
*/
hasher hash_function() const {
return static_cast<const Hash&>(*this);
}
key_equal key_eq() const {
return static_cast<const KeyEqual&>(*this);
}
/*
* Other
*/
iterator mutable_iterator(const_iterator pos) {
return iterator(m_values.begin() + iterator_to_index(pos));
}
iterator nth(size_type index) {
return iterator(m_values.begin() + index);
}
const_iterator nth(size_type index) const {
return const_iterator(m_values.cbegin() + index);
}
const_reference front() const {
return m_values.front();
}
const_reference back() const {
return m_values.back();
}
const values_container_type& values_container() const noexcept {
return m_values;
}
template<class U = values_container_type, typename std::enable_if<is_vector<U>::value>::type* = nullptr>
const typename values_container_type::value_type* data() const noexcept {
return m_values.data();
}
template<class U = values_container_type, typename std::enable_if<is_vector<U>::value>::type* = nullptr>
size_type capacity() const noexcept {
return m_values.capacity();
}
void shrink_to_fit() {
m_values.shrink_to_fit();
}
template<typename P>
std::pair<iterator, bool> insert_at_position(const_iterator pos, P&& value) {
return insert_at_position_impl(pos.m_iterator, KeySelect()(value), std::forward<P>(value));
}
template<class... Args>
std::pair<iterator, bool> emplace_at_position(const_iterator pos, Args&&... args) {
return insert_at_position(pos, value_type(std::forward<Args>(args)...));
}
template<class K, class... Args>
std::pair<iterator, bool> try_emplace_at_position(const_iterator pos, K&& key, Args&&... value_args) {
return insert_at_position_impl(pos.m_iterator, key,
std::piecewise_construct,
std::forward_as_tuple(std::forward<K>(key)),
std::forward_as_tuple(std::forward<Args>(value_args)...));
}
void pop_back() {
tsl_assert(!empty());
erase(std::prev(end()));
}
/**
* Here to avoid `template<class K> size_type unordered_erase(const K& key)` being used when
* we use a iterator instead of a const_iterator.
*/
iterator unordered_erase(iterator pos) {
return unordered_erase(const_iterator(pos));
}
iterator unordered_erase(const_iterator pos) {
const std::size_t index_erase = iterator_to_index(pos);
unordered_erase(pos.key());
/*
* One element was deleted, index_erase now points to the next element as the elements after
* the deleted value were shifted to the left in m_values (will be end() if we deleted the last element).
*/
return begin() + index_erase;
}
template<class K>
size_type unordered_erase(const K& key) {
return unordered_erase(key, hash_key(key));
}
template<class K>
size_type unordered_erase(const K& key, std::size_t hash) {
auto it_bucket_key = find_key(key, hash);
if(it_bucket_key == m_buckets.end()) {
return 0;
}
/**
* If we are not erasing the last element in m_values, we swap
* the element we are erasing with the last element. We then would
* just have to do a pop_back() in m_values.
*/
if(!compare_keys(key, KeySelect()(back()))) {
auto it_bucket_last_elem = find_key(KeySelect()(back()), hash_key(KeySelect()(back())));
tsl_assert(it_bucket_last_elem != m_buckets.end());
tsl_assert(it_bucket_last_elem->index() == m_values.size() - 1);
using std::swap;
swap(m_values[it_bucket_key->index()], m_values[it_bucket_last_elem->index()]);
swap(it_bucket_key->index_ref(), it_bucket_last_elem->index_ref());
}
erase_value_from_bucket(it_bucket_key);
return 1;
}
friend bool operator==(const ordered_hash& lhs, const ordered_hash& rhs) {
return lhs.m_values == rhs.m_values;
}
friend bool operator!=(const ordered_hash& lhs, const ordered_hash& rhs) {
return lhs.m_values != rhs.m_values;
}
friend bool operator<(const ordered_hash& lhs, const ordered_hash& rhs) {
return lhs.m_values < rhs.m_values;
}
friend bool operator<=(const ordered_hash& lhs, const ordered_hash& rhs) {
return lhs.m_values <= rhs.m_values;
}
friend bool operator>(const ordered_hash& lhs, const ordered_hash& rhs) {
return lhs.m_values > rhs.m_values;
}
friend bool operator>=(const ordered_hash& lhs, const ordered_hash& rhs) {
return lhs.m_values >= rhs.m_values;
}
private:
template<class K>
std::size_t hash_key(const K& key) const {
return Hash::operator()(key);
}
template<class K1, class K2>
bool compare_keys(const K1& key1, const K2& key2) const {
return KeyEqual::operator()(key1, key2);
}
template<class K>
typename buckets_container_type::iterator find_key(const K& key, std::size_t hash) {
auto it = static_cast<const ordered_hash*>(this)->find_key(key, hash);
return m_buckets.begin() + std::distance(m_buckets.cbegin(), it);
}
/**
* Return bucket which has the key 'key' or m_buckets.end() if none.
*
* From the bucket_for_hash, search for the value until we either find an empty bucket
* or a bucket which has a value with a distance from its ideal bucket longer
* than the probe length for the value we are looking for.
*/
template<class K>
typename buckets_container_type::const_iterator find_key(const K& key, std::size_t hash) const {
for(std::size_t ibucket = bucket_for_hash(hash), dist_from_ideal_bucket = 0; ;
ibucket = next_bucket(ibucket), dist_from_ideal_bucket++)
{
if(m_buckets[ibucket].empty()) {
return m_buckets.end();
}
else if(m_buckets[ibucket].truncated_hash() == bucket_entry::truncate_hash(hash) &&
compare_keys(key, KeySelect()(m_values[m_buckets[ibucket].index()])))
{
return m_buckets.begin() + ibucket;
}
else if(dist_from_ideal_bucket > distance_from_ideal_bucket(ibucket)) {
return m_buckets.end();
}
}
}
void rehash_impl(size_type bucket_count) {
bucket_count = round_up_to_power_of_two(bucket_count);
tsl_assert(bucket_count > 0);
if(bucket_count == this->bucket_count()) {
return;
}
if(bucket_count > max_bucket_count()) {
throw std::length_error("The map exceeds its maxmimum size.");
}
buckets_container_type old_buckets(bucket_count);
m_buckets.swap(old_buckets);
// Everything should be noexcept from here.
m_mask = bucket_count - 1;
this->max_load_factor(m_max_load_factor);
m_grow_on_next_insert = false;
for(const bucket_entry& old_bucket: old_buckets) {
if(old_bucket.empty()) {
continue;
}
truncated_hash_type insert_hash = old_bucket.truncated_hash();
index_type insert_index = old_bucket.index();
for(std::size_t ibucket = bucket_for_hash(insert_hash), dist_from_ideal_bucket = 0; ;
ibucket = next_bucket(ibucket), dist_from_ideal_bucket++)
{
if(m_buckets[ibucket].empty()) {
m_buckets[ibucket].set_index(insert_index);
m_buckets[ibucket].set_hash(insert_hash);
break;
}
const std::size_t distance = distance_from_ideal_bucket(ibucket);
if(dist_from_ideal_bucket > distance) {
std::swap(insert_index, m_buckets[ibucket].index_ref());
std::swap(insert_hash, m_buckets[ibucket].truncated_hash_ref());
dist_from_ideal_bucket = distance;
}
}
}
}
template<class T = values_container_type, typename std::enable_if<is_vector<T>::value>::type* = nullptr>
void reserve_space_for_values(size_type count) {
m_values.reserve(count);
}
template<class T = values_container_type, typename std::enable_if<!is_vector<T>::value>::type* = nullptr>
void reserve_space_for_values(size_type /*count*/) {
}
/**
* Swap the empty bucket with the values on its right until we cross another empty bucket
* or if the other bucket has a distance_from_ideal_bucket == 0.
*/
void backward_shift(std::size_t empty_ibucket) noexcept {
tsl_assert(m_buckets[empty_ibucket].empty());
std::size_t previous_ibucket = empty_ibucket;
for(std::size_t current_ibucket = next_bucket(previous_ibucket);
!m_buckets[current_ibucket].empty() && distance_from_ideal_bucket(current_ibucket) > 0;
previous_ibucket = current_ibucket, current_ibucket = next_bucket(current_ibucket))
{
std::swap(m_buckets[current_ibucket], m_buckets[previous_ibucket]);
}
}
void erase_value_from_bucket(typename buckets_container_type::iterator it_bucket) {
tsl_assert(it_bucket != m_buckets.end() && !it_bucket->empty());
m_values.erase(m_values.begin() + it_bucket->index());
/*
* m_values.erase shifted all the values on the right of the erased value,
* shift the indexes by 1 in the buckets array for these values.
*/
if(it_bucket->index() != m_values.size()) {
shift_indexes_in_buckets(it_bucket->index(), short(1));
}
// Mark the bucket as empty and do a backward shift of the values on the right
it_bucket->clear();
backward_shift(std::size_t(std::distance(m_buckets.begin(), it_bucket)));
}
/**
* Go through each value from [from_ivalue, m_values.size()) in m_values and for each
* bucket corresponding to the value, shift the indexes to the left by delta.
*/
void shift_indexes_in_buckets(index_type from_ivalue, short delta) noexcept {
static_assert(std::is_unsigned<index_type>::value && sizeof(index_type) >= sizeof(short),
"index_type should be unsigned and sizeof(index_type) >= sizeof(short)");
for(std::size_t ivalue = from_ivalue; ivalue < m_values.size(); ivalue++) {
std::size_t ibucket = bucket_for_hash(hash_key(KeySelect()(m_values[ivalue])));
// Modulo arithmetic, we should be alright for index_type(ivalue + delta). TODO further checks
while(m_buckets[ibucket].index() != index_type(ivalue + delta)) {
ibucket = next_bucket(ibucket);
}
m_buckets[ibucket].set_index(index_type(m_buckets[ibucket].index() - delta));
}
}
template<class K>
size_type erase_impl(const K& key, std::size_t hash) {
auto it_bucket = find_key(key, hash);
if(it_bucket != m_buckets.end()) {
erase_value_from_bucket(it_bucket);
return 1;
}
else {
return 0;
}
}
template<class K, class... Args>
std::pair<iterator, bool> insert_impl(const K& key, Args&&... value_type_args) {
return insert_at_position_impl(m_values.cend(), key, std::forward<Args>(value_type_args)...);
}
/**
* Insert the element before insert_position.
*/
template<class K, class... Args>
std::pair<iterator, bool> insert_at_position_impl(typename values_container_type::const_iterator insert_position,
const K& key, Args&&... value_type_args)
{
const std::size_t hash = hash_key(key);
std::size_t ibucket = bucket_for_hash(hash);
std::size_t dist_from_ideal_bucket = 0;
while(!m_buckets[ibucket].empty() && dist_from_ideal_bucket <= distance_from_ideal_bucket(ibucket)) {
if(m_buckets[ibucket].truncated_hash() == bucket_entry::truncate_hash(hash) &&
compare_keys(key, KeySelect()(m_values[m_buckets[ibucket].index()])))
{
return std::make_pair(begin() + m_buckets[ibucket].index(), false);
}
ibucket = next_bucket(ibucket);
dist_from_ideal_bucket++;
}
if(size() >= max_size()) {
throw std::length_error("We reached the maximum size for the hash table.");
}
if(grow_on_high_load()) {
ibucket = bucket_for_hash(hash);
dist_from_ideal_bucket = 0;
}
const index_type index_insert_position = index_type(std::distance(m_values.cbegin(), insert_position));
#ifdef TSL_NO_CONTAINER_EMPLACE_CONST_ITERATOR
m_values.emplace(m_values.begin() + std::distance(m_values.cbegin(), insert_position), std::forward<Args>(value_type_args)...);
#else
m_values.emplace(insert_position, std::forward<Args>(value_type_args)...);
#endif
insert_index(ibucket, dist_from_ideal_bucket,
index_insert_position, bucket_entry::truncate_hash(hash));
/*
* The insertion didn't happend at the end of the m_values container,
* we need to shift the indexes in m_buckets.
*/
if(index_insert_position != m_values.size() - 1) {
shift_indexes_in_buckets(index_insert_position + 1, short(-1));
}
return std::make_pair(iterator(m_values.begin() + index_insert_position), true);
}
void insert_index(std::size_t ibucket, std::size_t dist_from_ideal_bucket,
index_type index_insert, truncated_hash_type hash_insert) noexcept
{
while(!m_buckets[ibucket].empty()) {
const std::size_t distance = distance_from_ideal_bucket(ibucket);
if(dist_from_ideal_bucket > distance) {
std::swap(index_insert, m_buckets[ibucket].index_ref());
std::swap(hash_insert, m_buckets[ibucket].truncated_hash_ref());
dist_from_ideal_bucket = distance;
}
ibucket = next_bucket(ibucket);
dist_from_ideal_bucket++;
if(dist_from_ideal_bucket > REHASH_ON_HIGH_NB_PROBES__NPROBES && !m_grow_on_next_insert &&
load_factor() >= REHASH_ON_HIGH_NB_PROBES__MIN_LOAD_FACTOR)
{
// We don't want to grow the map now as we need this method to be noexcept.
// Do it on next insert.
m_grow_on_next_insert = true;
}
}
m_buckets[ibucket].set_index(index_insert);
m_buckets[ibucket].set_hash(hash_insert);
}
std::size_t distance_from_ideal_bucket(std::size_t ibucket) const noexcept {
const std::size_t ideal_bucket = bucket_for_hash(m_buckets[ibucket].truncated_hash());
if(ibucket >= ideal_bucket) {
return ibucket - ideal_bucket;
}
// If the bucket is smaller than the ideal bucket for the value, there was a wrapping at the end of the
// bucket array due to the modulo.
else {
return (bucket_count() + ibucket) - ideal_bucket;
}
}
std::size_t next_bucket(std::size_t index) const noexcept {
tsl_assert(index < m_buckets.size());
index++;
return (index < m_buckets.size())?index:0;
}
std::size_t bucket_for_hash(std::size_t hash) const noexcept {
return hash & m_mask;
}
std::size_t iterator_to_index(const_iterator it) const noexcept {
const auto dist = std::distance(cbegin(), it);
tsl_assert(dist >= 0);
return std::size_t(dist);
}
/**
* Return true if the map has been rehashed.
*/
bool grow_on_high_load() {
if(m_grow_on_next_insert || size() >= m_load_threshold) {
rehash_impl(bucket_count() * 2);
m_grow_on_next_insert = false;
return true;
}
else {
return false;
}
}
static std::size_t round_up_to_power_of_two(std::size_t value) {
if(is_power_of_two(value)) {
return value;
}
if(value == 0) {
return 1;
}
--value;
for(std::size_t i = 1; i < sizeof(std::size_t) * CHAR_BIT; i *= 2) {
value |= value >> i;
}
return value + 1;
}
static constexpr bool is_power_of_two(std::size_t value) {
return value != 0 && (value & (value - 1)) == 0;
}
public:
static const size_type DEFAULT_INIT_BUCKETS_SIZE = 16;
static constexpr float DEFAULT_MAX_LOAD_FACTOR = 0.75f;
private:
static const size_type REHASH_ON_HIGH_NB_PROBES__NPROBES = 128;
static constexpr float REHASH_ON_HIGH_NB_PROBES__MIN_LOAD_FACTOR = 0.15f;
private:
buckets_container_type m_buckets;
size_type m_mask;
values_container_type m_values;
bool m_grow_on_next_insert;
float m_max_load_factor;
size_type m_load_threshold;
};
} // end namespace detail_ordered_hash
} // end namespace tsl
#endif
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