/**
 * MIT License
 *
 * Copyright (c) 2017 Thibaut Goetghebuer-Planchon <tessil@gmx.com>
 *
 * 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_SPARSE_MAP_H
#define TSL_SPARSE_MAP_H

#include <cstddef>
#include <functional>
#include <initializer_list>
#include <memory>
#include <type_traits>
#include <utility>

#include "sparse_hash.h"

namespace tsl {

/**
 * Implementation of a sparse hash map using open-addressing with quadratic
 * probing. The goal on the hash map is to be the most memory efficient
 * possible, even at low load factor, while keeping reasonable performances.
 *
 * `GrowthPolicy` defines how the map grows and consequently how a hash value is
 * mapped to a bucket. By default the map uses
 * `tsl::sh::power_of_two_growth_policy`. This policy keeps the number of
 * buckets to a power of two and uses a mask to map the hash to a bucket instead
 * of the slow modulo. Other growth policies are available and you may define
 * your own growth policy, check `tsl::sh::power_of_two_growth_policy` for the
 * interface.
 *
 * `ExceptionSafety` defines the exception guarantee provided by the class. By
 * default only the basic exception safety is guaranteed which mean that all
 * resources used by the hash map will be freed (no memory leaks) but the hash
 * map may end-up in an undefined state if an exception is thrown (undefined
 * here means that some elements may be missing). This can ONLY happen on rehash
 * (either on insert or if `rehash` is called explicitly) and will occur if the
 * Allocator can't allocate memory (`std::bad_alloc`) or if the copy constructor
 * (when a nothrow move constructor is not available) throws an exception. This
 * can be avoided by calling `reserve` beforehand. This basic guarantee is
 * similar to the one of `google::sparse_hash_map` and `spp::sparse_hash_map`.
 * It is possible to ask for the strong exception guarantee with
 * `tsl::sh::exception_safety::strong`, the drawback is that the map will be
 * slower on rehashes and will also need more memory on rehashes.
 *
 * `Sparsity` defines how much the hash set will compromise between insertion
 * speed and memory usage. A high sparsity means less memory usage but longer
 * insertion times, and vice-versa for low sparsity. The default
 * `tsl::sh::sparsity::medium` sparsity offers a good compromise. It doesn't
 * change the lookup speed.
 *
 * `Key` and `T` must be nothrow move constructible and/or copy constructible.
 *
 * If the destructor of `Key` or `T` throws an exception, the 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.
 *  - erase: always invalidate the iterators.
 */
template <class Key, class T, class Hash = std::hash<Key>, class KeyEqual = std::equal_to<Key>,
		  class Allocator = std::allocator<std::pair<Key, T>>, class GrowthPolicy = tsl::sh::power_of_two_growth_policy<2>,
		  tsl::sh::exception_safety ExceptionSafety = tsl::sh::exception_safety::basic,
		  tsl::sh::sparsity Sparsity = tsl::sh::sparsity::medium>
class sparse_map {
private:
	template <typename U>
	using has_is_transparent = tsl::detail_sparse_hash::has_is_transparent<U>;

	class KeySelect {
	public:
		using key_type = Key;

		const key_type &operator()(const std::pair<Key, T> &key_value) const noexcept { return key_value.first; }

		key_type &operator()(std::pair<Key, T> &key_value) noexcept { return key_value.first; }
	};

	class ValueSelect {
	public:
		using value_type = T;

		const value_type &operator()(const std::pair<Key, T> &key_value) const noexcept { return key_value.second; }

		value_type &operator()(std::pair<Key, T> &key_value) noexcept { return key_value.second; }
	};

	using ht = detail_sparse_hash::sparse_hash<std::pair<Key, T>, KeySelect, ValueSelect, Hash, KeyEqual, Allocator, GrowthPolicy,
											   ExceptionSafety, Sparsity, tsl::sh::probing::quadratic>;

public:
	using key_type = typename ht::key_type;
	using mapped_type = T;
	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;

public:
	/*
	 * Constructors
	 */
	sparse_map() : sparse_map(ht::DEFAULT_INIT_BUCKET_COUNT) {}

	explicit sparse_map(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) {}

	sparse_map(size_type bucket_count, const Allocator &alloc) : sparse_map(bucket_count, Hash(), KeyEqual(), alloc) {}

	sparse_map(size_type bucket_count, const Hash &hash, const Allocator &alloc) : sparse_map(bucket_count, hash, KeyEqual(), alloc) {}

	explicit sparse_map(const Allocator &alloc) : sparse_map(ht::DEFAULT_INIT_BUCKET_COUNT, alloc) {}

	template <class InputIt>
	sparse_map(InputIt first, InputIt last, size_type bucket_count = ht::DEFAULT_INIT_BUCKET_COUNT, const Hash &hash = Hash(),
			   const KeyEqual &equal = KeyEqual(), const Allocator &alloc = Allocator())
		: sparse_map(bucket_count, hash, equal, alloc) {
		insert(first, last);
	}

	template <class InputIt>
	sparse_map(InputIt first, InputIt last, size_type bucket_count, const Allocator &alloc)
		: sparse_map(first, last, bucket_count, Hash(), KeyEqual(), alloc) {}

	template <class InputIt>
	sparse_map(InputIt first, InputIt last, size_type bucket_count, const Hash &hash, const Allocator &alloc)
		: sparse_map(first, last, bucket_count, hash, KeyEqual(), alloc) {}

	sparse_map(std::initializer_list<value_type> init, size_type bucket_count = ht::DEFAULT_INIT_BUCKET_COUNT, const Hash &hash = Hash(),
			   const KeyEqual &equal = KeyEqual(), const Allocator &alloc = Allocator())
		: sparse_map(init.begin(), init.end(), bucket_count, hash, equal, alloc) {}

	sparse_map(std::initializer_list<value_type> init, size_type bucket_count, const Allocator &alloc)
		: sparse_map(init.begin(), init.end(), bucket_count, Hash(), KeyEqual(), alloc) {}

	sparse_map(std::initializer_list<value_type> init, size_type bucket_count, const Hash &hash, const Allocator &alloc)
		: sparse_map(init.begin(), init.end(), bucket_count, hash, KeyEqual(), alloc) {}

	sparse_map &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(); }
	void add_destroy_task(detail_sparse_hash::ThreadTaskQueue *q) { m_ht.add_destroy_task(q); }

	std::pair<iterator, bool> insert(const value_type &value) { return m_ht.insert(value); }

	template <class P, typename std::enable_if<std::is_constructible<value_type, P &&>::value>::type * = nullptr>
	std::pair<iterator, bool> insert(P &&value) {
		return m_ht.emplace(std::forward<P>(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(hint, value); }

	template <class P, typename std::enable_if<std::is_constructible<value_type, P &&>::value>::type * = nullptr>
	iterator insert(const_iterator hint, P &&value) {
		return m_ht.emplace_hint(hint, std::forward<P>(value));
	}

	iterator insert(const_iterator hint, value_type &&value) { return m_ht.insert_hint(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()); }

	template <class M>
	std::pair<iterator, bool> insert_or_assign(const key_type &k, M &&obj) {
		return m_ht.insert_or_assign(k, std::forward<M>(obj));
	}

	template <class M>
	std::pair<iterator, bool> insert_or_assign(key_type &&k, M &&obj) {
		return m_ht.insert_or_assign(std::move(k), std::forward<M>(obj));
	}

	template <class M>
	iterator insert_or_assign(const_iterator hint, const key_type &k, M &&obj) {
		return m_ht.insert_or_assign(hint, k, std::forward<M>(obj));
	}

	template <class M>
	iterator insert_or_assign(const_iterator hint, key_type &&k, M &&obj) {
		return m_ht.insert_or_assign(hint, std::move(k), std::forward<M>(obj));
	}

	/**
	 * 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)...);
	}

	template <class... Args>
	std::pair<iterator, bool> try_emplace(const key_type &k, Args &&...args) {
		return m_ht.try_emplace(k, std::forward<Args>(args)...);
	}

	template <class... Args>
	std::pair<iterator, bool> try_emplace(key_type &&k, Args &&...args) {
		return m_ht.try_emplace(std::move(k), std::forward<Args>(args)...);
	}

	template <class... Args>
	iterator try_emplace(const_iterator hint, const key_type &k, Args &&...args) {
		return m_ht.try_emplace_hint(hint, k, std::forward<Args>(args)...);
	}

	template <class... Args>
	iterator try_emplace(const_iterator hint, key_type &&k, Args &&...args) {
		return m_ht.try_emplace_hint(hint, std::move(k), 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)`, otherwise the
	 * behaviour is undefined. Useful to speed-up the lookup 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)`, otherwise the
	 * behaviour is undefined. Useful 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 erase(const K &key, std::size_t precalculated_hash) {
		return m_ht.erase(key, precalculated_hash);
	}

	void swap(sparse_map &other) { other.m_ht.swap(m_ht); }

	/*
	 * Lookup
	 */
	T &at(const Key &key) { return m_ht.at(key); }

	/**
	 * Use the hash value `precalculated_hash` instead of hashing the key. The
	 * hash value should be the same as `hash_function()(key)`, otherwise the
	 * behaviour is undefined. Useful to speed-up the lookup if you already have
	 * the hash.
	 */
	T &at(const Key &key, std::size_t precalculated_hash) { return m_ht.at(key, precalculated_hash); }

	const T &at(const Key &key) const { return m_ht.at(key); }

	/**
	 * @copydoc at(const Key& key, std::size_t precalculated_hash)
	 */
	const T &at(const Key &key, std::size_t precalculated_hash) const { return m_ht.at(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>
	T &at(const K &key) {
		return m_ht.at(key);
	}

	/**
	 * @copydoc at(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)`, otherwise the
	 * behaviour is undefined. Useful 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>
	T &at(const K &key, std::size_t precalculated_hash) {
		return m_ht.at(key, precalculated_hash);
	}

	/**
	 * @copydoc at(const K& key)
	 */
	template <class K, class KE = KeyEqual, typename std::enable_if<has_is_transparent<KE>::value>::type * = nullptr>
	const T &at(const K &key) const {
		return m_ht.at(key);
	}

	/**
	 * @copydoc at(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>
	const T &at(const K &key, std::size_t precalculated_hash) const {
		return m_ht.at(key, precalculated_hash);
	}

	T &operator[](const Key &key) { return m_ht[key]; }
	T &operator[](Key &&key) { return m_ht[std::move(key)]; }

	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)`, otherwise the
	 * behaviour is undefined. Useful 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)`, otherwise the
	 * behaviour is undefined. Useful 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)`, otherwise the
	 * behaviour is undefined. Useful 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)`, otherwise the
	 * behaviour is undefined. Useful 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)`, otherwise the
	 * behaviour is undefined. Useful 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);
	}

	bool contains(const Key &key) const { return m_ht.contains(key); }

	/**
	 * Use the hash value 'precalculated_hash' instead of hashing the key. The
	 * hash value should be the same as hash_function()(key). Useful to speed-up
	 * the lookup if you already have the hash.
	 */
	bool contains(const Key &key, std::size_t precalculated_hash) const { return m_ht.contains(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>
	bool contains(const K &key) const {
		return m_ht.contains(key);
	}

	/**
	 * @copydoc contains(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). Useful 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>
	bool contains(const K &key, std::size_t precalculated_hash) const {
		return m_ht.contains(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)`, otherwise the
	 * behaviour is undefined. Useful 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)`, otherwise the
	 * behaviour is undefined. Useful 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); }

	/**
	 * Serialize the map through the `serializer` parameter.
	 *
	 * The `serializer` parameter must be a function object that supports the
	 * following call:
	 *  - `template<typename U> void operator()(const U& value);` where the types
	 * `std::uint64_t`, `float` and `std::pair<Key, T>` must be supported for U.
	 *
	 * The implementation leaves binary compatibility (endianness, IEEE 754 for
	 * floats, ...) of the types it serializes in the hands of the `Serializer`
	 * function object if compatibility is required.
	 */
	template <class Serializer>
	void serialize(Serializer &serializer) const {
		m_ht.serialize(serializer);
	}

	/**
	 * Deserialize a previously serialized map through the `deserializer`
	 * parameter.
	 *
	 * The `deserializer` parameter must be a function object that supports the
	 * following calls:
	 *  - `template<typename U> U operator()();` where the types `std::uint64_t`,
	 * `float` and `std::pair<Key, T>` must be supported for U.
	 *
	 * If the deserialized hash map type is hash compatible with the serialized
	 * map, the deserialization process can be sped up by setting
	 * `hash_compatible` to true. To be hash compatible, the Hash, KeyEqual and
	 * GrowthPolicy must behave the same way than the ones used on the serialized
	 * map. The `std::size_t` must also be of the same size as the one on the
	 * platform used to serialize the map. If these criteria are not met, the
	 * behaviour is undefined with `hash_compatible` sets to true.
	 *
	 * The behaviour is undefined if the type `Key` and `T` of the `sparse_map`
	 * are not the same as the types used during serialization.
	 *
	 * The implementation leaves binary compatibility (endianness, IEEE 754 for
	 * floats, size of int, ...) of the types it deserializes in the hands of the
	 * `Deserializer` function object if compatibility is required.
	 */
	template <class Deserializer>
	static sparse_map deserialize(Deserializer &deserializer, bool hash_compatible = false) {
		sparse_map map(0);
		map.m_ht.deserialize(deserializer, hash_compatible);

		return map;
	}

	friend bool operator==(const sparse_map &lhs, const sparse_map &rhs) {
		if (lhs.size() != rhs.size()) {
			return false;
		}

		for (const auto &element_lhs : lhs) {
			const auto it_element_rhs = rhs.find(element_lhs.first);
			if (it_element_rhs == rhs.cend() || element_lhs.second != it_element_rhs->second) {
				return false;
			}
		}

		return true;
	}

	friend bool operator!=(const sparse_map &lhs, const sparse_map &rhs) { return !operator==(lhs, rhs); }

	friend void swap(sparse_map &lhs, sparse_map &rhs) { lhs.swap(rhs); }

private:
	ht m_ht;
};

/**
 * Same as `tsl::sparse_map<Key, T, Hash, KeyEqual, Allocator,
 * tsl::sh::prime_growth_policy>`.
 */
template <class Key, class T, class Hash = std::hash<Key>, class KeyEqual = std::equal_to<Key>,
		  class Allocator = std::allocator<std::pair<Key, T>>>
using sparse_pg_map = sparse_map<Key, T, Hash, KeyEqual, Allocator, tsl::sh::prime_growth_policy>;

}  // end namespace tsl

#endif
