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hopscotch_set.h
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hopscotch_set.h
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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_HOPSCOTCH_SET_H
#define TSL_HOPSCOTCH_SET_H
#include <algorithm>
#include <cstddef>
#include <functional>
#include <initializer_list>
#include <list>
#include <memory>
#include <type_traits>
#include <utility>
#include "hopscotch_hash.h"
namespace tsl {
/**
* Implementation of a hash set using the hopscotch hashing algorithm.
*
* The Key must be either nothrow move-constructible, copy-constuctible or both.
*
* The size of the neighborhood (NeighborhoodSize) must be > 0 and <= 62 if StoreHash is false.
* When StoreHash is true, 32-bits of the hash will be stored alongside the neighborhood limiting
* the NeighborhoodSize to <= 30. There is no memory usage difference between
* 'NeighborhoodSize 62; StoreHash false' and 'NeighborhoodSize 30; StoreHash true'.
*
* Storing the hash may improve performance on insert during the rehash process if the hash takes time
* to compute. It may also improve read performance if the KeyEqual function takes time (or incurs a cache-miss).
* If used with simple Hash and KeyEqual it may slow things down.
*
* StoreHash can only be set if the GrowthPolicy is set to tsl::power_of_two_growth_policy.
*
* GrowthPolicy defines how the set grows and consequently how a hash value is mapped to a bucket.
* By default the set uses tsl::power_of_two_growth_policy. This policy keeps the number of buckets
* to a power of two and uses a mask to set the hash to a bucket instead of the slow modulo.
* You may define your own growth policy, check tsl::power_of_two_growth_policy for the interface.
*
* If the destructor of Key throws an exception, behaviour of the class is undefined.
*
* Iterators invalidation:
* - clear, operator=, reserve, rehash: always invalidate the iterators.
* - insert, emplace, emplace_hint, operator[]: if there is an effective insert, invalidate the iterators
* if a displacement is needed to resolve a collision (which mean that most of the time,
* insert will invalidate the iterators). Or if there is a rehash.
* - erase: iterator on the erased element is the only one which become invalid.
*/
template<class Key,
class Hash = std::hash<Key>,
class KeyEqual = std::equal_to<Key>,
class Allocator = std::allocator<Key>,
unsigned int NeighborhoodSize = 62,
bool StoreHash = false,
class GrowthPolicy = tsl::power_of_two_growth_policy>
class hopscotch_set {
private:
template<typename U>
using has_is_transparent = tsl::detail_hopscotch_hash::has_is_transparent<U>;
class KeySelect {
public:
using key_type = Key;
const key_type& operator()(const Key& key) const {
return key;
}
key_type& operator()(Key& key) {
return key;
}
};
using overflow_container_type = std::list<Key, Allocator>;
using ht = detail_hopscotch_hash::hopscotch_hash<Key, KeySelect, void,
Hash, KeyEqual,
Allocator, NeighborhoodSize,
StoreHash, GrowthPolicy,
overflow_container_type>;
public:
using key_type = typename ht::key_type;
using value_type = typename ht::value_type;
using size_type = typename ht::size_type;
using difference_type = typename ht::difference_type;
using hasher = typename ht::hasher;
using key_equal = typename ht::key_equal;
using allocator_type = typename ht::allocator_type;
using reference = typename ht::reference;
using const_reference = typename ht::const_reference;
using pointer = typename ht::pointer;
using const_pointer = typename ht::const_pointer;
using iterator = typename ht::iterator;
using const_iterator = typename ht::const_iterator;
/*
* Constructors
*/
hopscotch_set() : hopscotch_set(ht::DEFAULT_INIT_BUCKETS_SIZE) {
}
explicit hopscotch_set(size_type bucket_count,
const Hash& hash = Hash(),
const KeyEqual& equal = KeyEqual(),
const Allocator& alloc = Allocator()) :
m_ht(bucket_count, hash, equal, alloc, ht::DEFAULT_MAX_LOAD_FACTOR)
{
}
hopscotch_set(size_type bucket_count,
const Allocator& alloc) : hopscotch_set(bucket_count, Hash(), KeyEqual(), alloc)
{
}
hopscotch_set(size_type bucket_count,
const Hash& hash,
const Allocator& alloc) : hopscotch_set(bucket_count, hash, KeyEqual(), alloc)
{
}
explicit hopscotch_set(const Allocator& alloc) : hopscotch_set(ht::DEFAULT_INIT_BUCKETS_SIZE, alloc) {
}
template<class InputIt>
hopscotch_set(InputIt first, InputIt last,
size_type bucket_count = ht::DEFAULT_INIT_BUCKETS_SIZE,
const Hash& hash = Hash(),
const KeyEqual& equal = KeyEqual(),
const Allocator& alloc = Allocator()) : hopscotch_set(bucket_count, hash, equal, alloc)
{
insert(first, last);
}
template<class InputIt>
hopscotch_set(InputIt first, InputIt last,
size_type bucket_count,
const Allocator& alloc) : hopscotch_set(first, last, bucket_count, Hash(), KeyEqual(), alloc)
{
}
template<class InputIt>
hopscotch_set(InputIt first, InputIt last,
size_type bucket_count,
const Hash& hash,
const Allocator& alloc) : hopscotch_set(first, last, bucket_count, hash, KeyEqual(), alloc)
{
}
hopscotch_set(std::initializer_list<value_type> init,
size_type bucket_count = ht::DEFAULT_INIT_BUCKETS_SIZE,
const Hash& hash = Hash(),
const KeyEqual& equal = KeyEqual(),
const Allocator& alloc = Allocator()) :
hopscotch_set(init.begin(), init.end(), bucket_count, hash, equal, alloc)
{
}
hopscotch_set(std::initializer_list<value_type> init,
size_type bucket_count,
const Allocator& alloc) :
hopscotch_set(init.begin(), init.end(), bucket_count, Hash(), KeyEqual(), alloc)
{
}
hopscotch_set(std::initializer_list<value_type> init,
size_type bucket_count,
const Hash& hash,
const Allocator& alloc) :
hopscotch_set(init.begin(), init.end(), bucket_count, hash, KeyEqual(), alloc)
{
}
hopscotch_set& operator=(std::initializer_list<value_type> ilist) {
m_ht.clear();
m_ht.reserve(ilist.size());
m_ht.insert(ilist.begin(), ilist.end());
return *this;
}
allocator_type get_allocator() const { return m_ht.get_allocator(); }
/*
* Iterators
*/
iterator begin() noexcept { return m_ht.begin(); }
const_iterator begin() const noexcept { return m_ht.begin(); }
const_iterator cbegin() const noexcept { return m_ht.cbegin(); }
iterator end() noexcept { return m_ht.end(); }
const_iterator end() const noexcept { return m_ht.end(); }
const_iterator cend() const noexcept { return m_ht.cend(); }
/*
* Capacity
*/
bool empty() const noexcept { return m_ht.empty(); }
size_type size() const noexcept { return m_ht.size(); }
size_type max_size() const noexcept { return m_ht.max_size(); }
/*
* Modifiers
*/
void clear() noexcept { m_ht.clear(); }
std::pair<iterator, bool> insert(const value_type& value) { return m_ht.insert(value); }
std::pair<iterator, bool> insert(value_type&& value) { return m_ht.insert(std::move(value)); }
iterator insert(const_iterator hint, const value_type& value) { return m_ht.insert(hint, value); }
iterator insert(const_iterator hint, value_type&& value) { return m_ht.insert(hint, std::move(value)); }
template<class InputIt>
void insert(InputIt first, InputIt last) { m_ht.insert(first, last); }
void insert(std::initializer_list<value_type> ilist) { m_ht.insert(ilist.begin(), ilist.end()); }
/**
* Due to the way elements are stored, emplace will need to move or copy the key-value once.
* The method is equivalent to insert(value_type(std::forward<Args>(args)...));
*
* Mainly here for compatibility with the std::unordered_map interface.
*/
template<class... Args>
std::pair<iterator, bool> emplace(Args&&... args) { return m_ht.emplace(std::forward<Args>(args)...); }
/**
* Due to the way elements are stored, emplace_hint will need to move or copy the key-value once.
* The method is equivalent to insert(hint, value_type(std::forward<Args>(args)...));
*
* Mainly here for compatibility with the std::unordered_map interface.
*/
template<class... Args>
iterator emplace_hint(const_iterator hint, Args&&... args) {
return m_ht.emplace_hint(hint, std::forward<Args>(args)...);
}
iterator erase(iterator pos) { return m_ht.erase(pos); }
iterator erase(const_iterator pos) { return m_ht.erase(pos); }
iterator erase(const_iterator first, const_iterator last) { return m_ht.erase(first, last); }
size_type erase(const key_type& key) { return m_ht.erase(key); }
/**
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup to the value if you already have the hash.
*/
size_type erase(const key_type& key, std::size_t precalculated_hash) {
return m_ht.erase(key, precalculated_hash);
}
/**
* This overload only participates in the overload resolution if the typedef KeyEqual::is_transparent exists.
* If so, K must be hashable and comparable to Key.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
size_type erase(const K& key) { return m_ht.erase(key); }
/**
* @copydoc erase(const K& key)
*
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup to the value if you already have the hash.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
size_type erase(const K& key, std::size_t precalculated_hash) {
return m_ht.erase(key, precalculated_hash);
}
void swap(hopscotch_set& other) { other.m_ht.swap(m_ht); }
/*
* Lookup
*/
size_type count(const Key& key) const { return m_ht.count(key); }
/**
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
size_type count(const Key& key, std::size_t precalculated_hash) const { return m_ht.count(key, precalculated_hash); }
/**
* This overload only participates in the overload resolution if the typedef KeyEqual::is_transparent exists.
* If so, K must be hashable and comparable to Key.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
size_type count(const K& key) const { return m_ht.count(key); }
/**
* @copydoc count(const K& key) const
*
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
size_type count(const K& key, std::size_t precalculated_hash) const { return m_ht.count(key, precalculated_hash); }
iterator find(const Key& key) { return m_ht.find(key); }
/**
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
iterator find(const Key& key, std::size_t precalculated_hash) { return m_ht.find(key, precalculated_hash); }
const_iterator find(const Key& key) const { return m_ht.find(key); }
/**
* @copydoc find(const Key& key, std::size_t precalculated_hash)
*/
const_iterator find(const Key& key, std::size_t precalculated_hash) const { return m_ht.find(key, precalculated_hash); }
/**
* This overload only participates in the overload resolution if the typedef KeyEqual::is_transparent exists.
* If so, K must be hashable and comparable to Key.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
iterator find(const K& key) { return m_ht.find(key); }
/**
* @copydoc find(const K& key)
*
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
iterator find(const K& key, std::size_t precalculated_hash) { return m_ht.find(key, precalculated_hash); }
/**
* @copydoc find(const K& key)
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
const_iterator find(const K& key) const { return m_ht.find(key); }
/**
* @copydoc find(const K& key)
*
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
const_iterator find(const K& key, std::size_t precalculated_hash) const { return m_ht.find(key, precalculated_hash); }
std::pair<iterator, iterator> equal_range(const Key& key) { return m_ht.equal_range(key); }
/**
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
std::pair<iterator, iterator> equal_range(const Key& key, std::size_t precalculated_hash) {
return m_ht.equal_range(key, precalculated_hash);
}
std::pair<const_iterator, const_iterator> equal_range(const Key& key) const { return m_ht.equal_range(key); }
/**
* @copydoc equal_range(const Key& key, std::size_t precalculated_hash)
*/
std::pair<const_iterator, const_iterator> equal_range(const Key& key, std::size_t precalculated_hash) const {
return m_ht.equal_range(key, precalculated_hash);
}
/**
* This overload only participates in the overload resolution if the typedef KeyEqual::is_transparent exists.
* If so, K must be hashable and comparable to Key.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
std::pair<iterator, iterator> equal_range(const K& key) { return m_ht.equal_range(key); }
/**
* @copydoc equal_range(const K& key)
*
* Use the hash value 'precalculated_hash' instead of hashing the key. The hash value should be the same
* as hash_function()(key). Usefull to speed-up the lookup if you already have the hash.
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
std::pair<iterator, iterator> equal_range(const K& key, std::size_t precalculated_hash) {
return m_ht.equal_range(key, precalculated_hash);
}
/**
* @copydoc equal_range(const K& key)
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
std::pair<const_iterator, const_iterator> equal_range(const K& key) const { return m_ht.equal_range(key); }
/**
* @copydoc equal_range(const K& key, std::size_t precalculated_hash)
*/
template<class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
std::pair<const_iterator, const_iterator> equal_range(const K& key, std::size_t precalculated_hash) const {
return m_ht.equal_range(key, precalculated_hash);
}
/*
* Bucket interface
*/
size_type bucket_count() const { return m_ht.bucket_count(); }
size_type max_bucket_count() const { return m_ht.max_bucket_count(); }
/*
* Hash policy
*/
float load_factor() const { return m_ht.load_factor(); }
float max_load_factor() const { return m_ht.max_load_factor(); }
void max_load_factor(float ml) { m_ht.max_load_factor(ml); }
void rehash(size_type count_) { m_ht.rehash(count_); }
void reserve(size_type count_) { m_ht.reserve(count_); }
/*
* Observers
*/
hasher hash_function() const { return m_ht.hash_function(); }
key_equal key_eq() const { return m_ht.key_eq(); }
/*
* Other
*/
/**
* Convert a const_iterator to an iterator.
*/
iterator mutable_iterator(const_iterator pos) {
return m_ht.mutable_iterator(pos);
}
size_type overflow_size() const noexcept { return m_ht.overflow_size(); }
friend bool operator==(const hopscotch_set& lhs, const hopscotch_set& rhs) {
if(lhs.size() != rhs.size()) {
return false;
}
for(const auto& element_lhs : lhs) {
const auto it_element_rhs = rhs.find(element_lhs);
if(it_element_rhs == rhs.cend()) {
return false;
}
}
return true;
}
friend bool operator!=(const hopscotch_set& lhs, const hopscotch_set& rhs) {
return !operator==(lhs, rhs);
}
friend void swap(hopscotch_set& lhs, hopscotch_set& rhs) {
lhs.swap(rhs);
}
private:
ht m_ht;
};
} // end namespace tsl
#endif