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Edit File : hashtable_policy.h \| Size : 66.38 KB
// Internal policy header for unordered_set and unordered_map -- C++ -- // Copyright (C) 2010-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library 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 3, or (at your option) // any later version. // This library 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. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file bits/hashtable_policy.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. * @headername{unordered_map,unordered_set} / #ifndef _HASHTABLE_POLICY_H #define _HASHTABLE_POLICY_H 1 #include <tuple> // for std::tuple, std::forward_as_tuple #include <cstdint> // for std::uint_fast64_t #include <bits/stl_algobase.h> // for std::min. namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> class _Hashtable; namespace __detail { /* * @defgroup hashtable-detail Base and Implementation Classes * @ingroup unordered_associative_containers * @{ / template<typename _Key, typename _Value, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _Traits> struct _Hashtable_base; // Helper function: return distance(first, last) for forward // iterators, or 0/1 for input iterators. template<class _Iterator> inline typename std::iterator_traits<_Iterator>::difference_type __distance_fw(_Iterator __first, _Iterator __last, std::input_iterator_tag) { return __first != __last ? 1 : 0; } template<class _Iterator> inline typename std::iterator_traits<_Iterator>::difference_type __distance_fw(_Iterator __first, _Iterator __last, std::forward_iterator_tag) { return std::distance(__first, __last); } template<class _Iterator> inline typename std::iterator_traits<_Iterator>::difference_type __distance_fw(_Iterator __first, _Iterator __last) { return __distance_fw(__first, __last, std::__iterator_category(__first)); } struct _Identity { template<typename _Tp> _Tp&& operator()(_Tp&& __x) const { return std::forward<_Tp>(__x); } }; struct _Select1st { template<typename _Tp> auto operator()(_Tp&& __x) const -> decltype(std::get<0>(std::forward<_Tp>(__x))) { return std::get<0>(std::forward<_Tp>(__x)); } }; template<typename _NodeAlloc> struct _Hashtable_alloc; // Functor recycling a pool of nodes and using allocation once the pool is // empty. template<typename _NodeAlloc> struct _ReuseOrAllocNode { private: using __node_alloc_type = _NodeAlloc; using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>; using __node_alloc_traits = typename __hashtable_alloc::__node_alloc_traits; using __node_type = typename __hashtable_alloc::__node_type; public: _ReuseOrAllocNode(__node_type __nodes, __hashtable_alloc& __h) : _M_nodes(__nodes), _M_h(__h) { } _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete; ~_ReuseOrAllocNode() { _M_h._M_deallocate_nodes(_M_nodes); } template<typename _Arg> __node_type* operator()(_Arg&& __arg) const { if (_M_nodes) { __node_type* __node = _M_nodes; _M_nodes = _M_nodes->_M_next(); __node->_M_nxt = nullptr; auto& __a = _M_h._M_node_allocator(); __node_alloc_traits::destroy(__a, __node->_M_valptr()); __try { __node_alloc_traits::construct(__a, __node->_M_valptr(), std::forward<_Arg>(__arg)); } __catch(...) { __node->~__node_type(); __node_alloc_traits::deallocate(__a, __node, 1); __throw_exception_again; } return __node; } return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); } private: mutable __node_type* _M_nodes; __hashtable_alloc& _M_h; }; // Functor similar to the previous one but without any pool of nodes to // recycle. template<typename _NodeAlloc> struct _AllocNode { private: using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>; using __node_type = typename __hashtable_alloc::__node_type; public: _AllocNode(__hashtable_alloc& __h) : _M_h(__h) { } template<typename _Arg> __node_type* operator()(_Arg&& __arg) const { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); } private: __hashtable_alloc& _M_h; }; // Auxiliary types used for all instantiations of _Hashtable nodes // and iterators. /** * struct _Hashtable_traits * * Important traits for hash tables. * * @tparam _Cache_hash_code Boolean value. True if the value of * the hash function is stored along with the value. This is a * time-space tradeoff. Storing it may improve lookup speed by * reducing the number of times we need to call the _Equal * function. * * @tparam _Constant_iterators Boolean value. True if iterator and * const_iterator are both constant iterator types. This is true * for unordered_set and unordered_multiset, false for * unordered_map and unordered_multimap. * * @tparam _Unique_keys Boolean value. True if the return value * of _Hashtable::count(k) is always at most one, false if it may * be an arbitrary number. This is true for unordered_set and * unordered_map, false for unordered_multiset and * unordered_multimap. / template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys> struct _Hashtable_traits { using __hash_cached = __bool_constant<_Cache_hash_code>; using __constant_iterators = __bool_constant<_Constant_iterators>; using __unique_keys = __bool_constant<_Unique_keys>; }; /* * struct _Hash_node_base * * Nodes, used to wrap elements stored in the hash table. A policy * template parameter of class template _Hashtable controls whether * nodes also store a hash code. In some cases (e.g. strings) this * may be a performance win. / struct _Hash_node_base { _Hash_node_base _M_nxt; _Hash_node_base() noexcept : _M_nxt() { } _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { } }; /** * struct _Hash_node_value_base * * Node type with the value to store. / template<typename _Value> struct _Hash_node_value_base : _Hash_node_base { typedef _Value value_type; __gnu_cxx::__aligned_buffer<_Value> _M_storage; _Value _M_valptr() noexcept { return _M_storage._M_ptr(); } const _Value* _M_valptr() const noexcept { return _M_storage._M_ptr(); } _Value& _M_v() noexcept { return _M_valptr(); } const _Value& _M_v() const noexcept { return _M_valptr(); } }; /** * Primary template struct _Hash_node. / template<typename _Value, bool _Cache_hash_code> struct _Hash_node; /* * Specialization for nodes with caches, struct _Hash_node. * * Base class is __detail::_Hash_node_value_base. / template<typename _Value> struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value> { std::size_t _M_hash_code; _Hash_node _M_next() const noexcept { return static_cast<_Hash_node>(this->_M_nxt); } }; /* * Specialization for nodes without caches, struct _Hash_node. * * Base class is __detail::_Hash_node_value_base. / template<typename _Value> struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value> { _Hash_node _M_next() const noexcept { return static_cast<_Hash_node>(this->_M_nxt); } }; /// Base class for node iterators. template<typename _Value, bool _Cache_hash_code> struct _Node_iterator_base { using __node_type = _Hash_node<_Value, _Cache_hash_code>; __node_type _M_cur; _Node_iterator_base(__node_type* __p) noexcept : _M_cur(__p) { } void _M_incr() noexcept { _M_cur = _M_cur->_M_next(); } }; template<typename _Value, bool _Cache_hash_code> inline bool operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x, const _Node_iterator_base<_Value, _Cache_hash_code >& __y) noexcept { return __x._M_cur == __y._M_cur; } template<typename _Value, bool _Cache_hash_code> inline bool operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x, const _Node_iterator_base<_Value, _Cache_hash_code>& __y) noexcept { return __x._M_cur != __y._M_cur; } /// Node iterators, used to iterate through all the hashtable. template<typename _Value, bool __constant_iterators, bool __cache> struct _Node_iterator : public _Node_iterator_base<_Value, __cache> { private: using __base_type = _Node_iterator_base<_Value, __cache>; using __node_type = typename __base_type::__node_type; public: typedef _Value value_type; typedef std::ptrdiff_t difference_type; typedef std::forward_iterator_tag iterator_category; using pointer = typename std::conditional<__constant_iterators, const _Value, _Value>::type; using reference = typename std::conditional<__constant_iterators, const _Value&, _Value&>::type; _Node_iterator() noexcept : __base_type(0) { } explicit _Node_iterator(__node_type* __p) noexcept : __base_type(__p) { } reference operator() const noexcept { return this->_M_cur->_M_v(); } pointer operator->() const noexcept { return this->_M_cur->_M_valptr(); } _Node_iterator& operator++() noexcept { this->_M_incr(); return this; } _Node_iterator operator++(int) noexcept { _Node_iterator __tmp(this); this->_M_incr(); return __tmp; } }; /// Node const_iterators, used to iterate through all the hashtable. template<typename _Value, bool __constant_iterators, bool __cache> struct _Node_const_iterator : public _Node_iterator_base<_Value, __cache> { private: using __base_type = _Node_iterator_base<_Value, __cache>; using __node_type = typename __base_type::__node_type; public: typedef _Value value_type; typedef std::ptrdiff_t difference_type; typedef std::forward_iterator_tag iterator_category; typedef const _Value pointer; typedef const _Value& reference; _Node_const_iterator() noexcept : __base_type(0) { } explicit _Node_const_iterator(__node_type* __p) noexcept : __base_type(__p) { } _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators, __cache>& __x) noexcept : __base_type(__x._M_cur) { } reference operator() const noexcept { return this->_M_cur->_M_v(); } pointer operator->() const noexcept { return this->_M_cur->_M_valptr(); } _Node_const_iterator& operator++() noexcept { this->_M_incr(); return this; } _Node_const_iterator operator++(int) noexcept { _Node_const_iterator __tmp(this); this->_M_incr(); return __tmp; } }; // Many of class template _Hashtable's template parameters are policy // classes. These are defaults for the policies. /// Default range hashing function: use division to fold a large number /// into the range [0, N). struct _Mod_range_hashing { typedef std::size_t first_argument_type; typedef std::size_t second_argument_type; typedef std::size_t result_type; result_type operator()(first_argument_type __num, second_argument_type __den) const noexcept { return __num % __den; } }; /// Default ranged hash function H. In principle it should be a /// function object composed from objects of type H1 and H2 such that /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of /// h1 and h2. So instead we'll just use a tag to tell class template /// hashtable to do that composition. struct _Default_ranged_hash { }; /// Default value for rehash policy. Bucket size is (usually) the /// smallest prime that keeps the load factor small enough. struct _Prime_rehash_policy { using __has_load_factor = std::true_type; _Prime_rehash_policy(float __z = 1.0) noexcept : _M_max_load_factor(__z), _M_next_resize(0) { } float max_load_factor() const noexcept { return _M_max_load_factor; } // Return a bucket size no smaller than n. std::size_t _M_next_bkt(std::size_t __n) const; // Return a bucket count appropriate for n elements std::size_t _M_bkt_for_elements(std::size_t __n) const { return __builtin_ceil(__n / (long double)_M_max_load_factor); } // __n_bkt is current bucket count, __n_elt is current element count, // and __n_ins is number of elements to be inserted. Do we need to // increase bucket count? If so, return make_pair(true, n), where n // is the new bucket count. If not, return make_pair(false, 0). std::pair<bool, std::size_t> _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt, std::size_t __n_ins) const; typedef std::size_t _State; _State _M_state() const { return _M_next_resize; } void _M_reset() noexcept { _M_next_resize = 0; } void _M_reset(_State __state) { _M_next_resize = __state; } static const std::size_t _S_growth_factor = 2; float _M_max_load_factor; mutable std::size_t _M_next_resize; }; /// Range hashing function assuming that second arg is a power of 2. struct _Mask_range_hashing { typedef std::size_t first_argument_type; typedef std::size_t second_argument_type; typedef std::size_t result_type; result_type operator()(first_argument_type __num, second_argument_type __den) const noexcept { return __num & (__den - 1); } }; /// Compute closest power of 2. _GLIBCXX14_CONSTEXPR inline std::size_t __clp2(std::size_t __n) noexcept { #if __SIZEOF_SIZE_T__ >= 8 std::uint_fast64_t __x = __n; #else std::uint_fast32_t __x = __n; #endif // Algorithm from Hacker's Delight, Figure 3-3. __x = __x - 1; __x = __x \| (__x >> 1); __x = __x \| (__x >> 2); __x = __x \| (__x >> 4); __x = __x \| (__x >> 8); __x = __x \| (__x >>16); #if __SIZEOF_SIZE_T__ >= 8 __x = __x \| (__x >>32); #endif return __x + 1; } /// Rehash policy providing power of 2 bucket numbers. Avoids modulo /// operations. struct _Power2_rehash_policy { using __has_load_factor = std::true_type; _Power2_rehash_policy(float __z = 1.0) noexcept : _M_max_load_factor(__z), _M_next_resize(0) { } float max_load_factor() const noexcept { return _M_max_load_factor; } // Return a bucket size no smaller than n (as long as n is not above the // highest power of 2). std::size_t _M_next_bkt(std::size_t __n) noexcept { const auto __max_width = std::min<size_t>(sizeof(size_t), 8); const auto __max_bkt = size_t(1) << (__max_width __CHAR_BIT__ - 1); std::size_t __res = __clp2(__n); if (__res == __n) __res <<= 1; if (__res == 0) __res = __max_bkt; if (__res == __max_bkt) // Set next resize to the max value so that we never try to rehash again // as we already reach the biggest possible bucket number. // Note that it might result in max_load_factor not being respected. _M_next_resize = std::size_t(-1); else _M_next_resize = __builtin_ceil(__res * (long double)_M_max_load_factor); return __res; } // Return a bucket count appropriate for n elements std::size_t _M_bkt_for_elements(std::size_t __n) const noexcept { return __builtin_ceil(__n / (long double)_M_max_load_factor); } // __n_bkt is current bucket count, __n_elt is current element count, // and __n_ins is number of elements to be inserted. Do we need to // increase bucket count? If so, return make_pair(true, n), where n // is the new bucket count. If not, return make_pair(false, 0). std::pair<bool, std::size_t> _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt, std::size_t __n_ins) noexcept { if (__n_elt + __n_ins >= _M_next_resize) { long double __min_bkts = (__n_elt + __n_ins) / (long double)_M_max_load_factor; if (__min_bkts >= __n_bkt) return std::make_pair(true, _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1, __n_bkt * _S_growth_factor))); _M_next_resize = __builtin_floor(__n_bkt * (long double)_M_max_load_factor); return std::make_pair(false, 0); } else return std::make_pair(false, 0); } typedef std::size_t _State; _State _M_state() const noexcept { return _M_next_resize; } void _M_reset() noexcept { _M_next_resize = 0; } void _M_reset(_State __state) noexcept { _M_next_resize = __state; } static const std::size_t _S_growth_factor = 2; float _M_max_load_factor; std::size_t _M_next_resize; }; // Base classes for std::_Hashtable. We define these base classes // because in some cases we want to do different things depending on // the value of a policy class. In some cases the policy class // affects which member functions and nested typedefs are defined; // we handle that by specializing base class templates. Several of // the base class templates need to access other members of class // template _Hashtable, so we use a variant of the "Curiously // Recurring Template Pattern" (CRTP) technique. /** * Primary class template _Map_base. * * If the hashtable has a value type of the form pair<T1, T2> and a * key extraction policy (_ExtractKey) that returns the first part * of the pair, the hashtable gets a mapped_type typedef. If it * satisfies those criteria and also has unique keys, then it also * gets an operator[]. / template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits, bool _Unique_keys = _Traits::__unique_keys::value> struct _Map_base { }; /// Partial specialization, __unique_keys set to false. template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, false> { using mapped_type = typename std::tuple_element<1, _Pair>::type; }; /// Partial specialization, __unique_keys set to true. template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true> { private: using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair, _Select1st, _Equal, _H1, _H2, _Hash, _Traits>; using __hashtable = _Hashtable<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; using __hash_code = typename __hashtable_base::__hash_code; using __node_type = typename __hashtable_base::__node_type; public: using key_type = typename __hashtable_base::key_type; using iterator = typename __hashtable_base::iterator; using mapped_type = typename std::tuple_element<1, _Pair>::type; mapped_type& operator[](const key_type& __k); mapped_type& operator[](key_type&& __k); // _GLIBCXX_RESOLVE_LIB_DEFECTS // DR 761. unordered_map needs an at() member function. mapped_type& at(const key_type& __k); const mapped_type& at(const key_type& __k) const; }; template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> auto _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true>:: operator[](const key_type& __k) -> mapped_type& { __hashtable __h = static_cast<__hashtable>(this); __hash_code __code = __h->_M_hash_code(__k); std::size_t __n = __h->_M_bucket_index(__k, __code); __node_type __p = __h->_M_find_node(__n, __k, __code); if (!__p) { __p = __h->_M_allocate_node(std::piecewise_construct, std::tuple<const key_type&>(__k), std::tuple<>()); return __h->_M_insert_unique_node(__n, __code, __p)->second; } return __p->_M_v().second; } template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> auto _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true>:: operator[](key_type&& __k) -> mapped_type& { __hashtable* __h = static_cast<__hashtable>(this); __hash_code __code = __h->_M_hash_code(__k); std::size_t __n = __h->_M_bucket_index(__k, __code); __node_type __p = __h->_M_find_node(__n, __k, __code); if (!__p) { __p = __h->_M_allocate_node(std::piecewise_construct, std::forward_as_tuple(std::move(__k)), std::tuple<>()); return __h->_M_insert_unique_node(__n, __code, __p)->second; } return __p->_M_v().second; } template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> auto _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true>:: at(const key_type& __k) -> mapped_type& { __hashtable* __h = static_cast<__hashtable>(this); __hash_code __code = __h->_M_hash_code(__k); std::size_t __n = __h->_M_bucket_index(__k, __code); __node_type __p = __h->_M_find_node(__n, __k, __code); if (!__p) __throw_out_of_range(__N("_Map_base::at")); return __p->_M_v().second; } template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> auto _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true>:: at(const key_type& __k) const -> const mapped_type& { const __hashtable* __h = static_cast<const __hashtable>(this); __hash_code __code = __h->_M_hash_code(__k); std::size_t __n = __h->_M_bucket_index(__k, __code); __node_type __p = __h->_M_find_node(__n, __k, __code); if (!__p) __throw_out_of_range(__N("_Map_base::at")); return __p->_M_v().second; } /** * Primary class template _Insert_base. * * Defines @c insert member functions appropriate to all _Hashtables. / template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Insert_base { protected: using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>; using value_type = typename __hashtable_base::value_type; using iterator = typename __hashtable_base::iterator; using const_iterator = typename __hashtable_base::const_iterator; using size_type = typename __hashtable_base::size_type; using __unique_keys = typename __hashtable_base::__unique_keys; using __ireturn_type = typename __hashtable_base::__ireturn_type; using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>; using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>; using __node_gen_type = _AllocNode<__node_alloc_type>; __hashtable& _M_conjure_hashtable() { return (static_cast<__hashtable>(this)); } template<typename _InputIterator, typename _NodeGetter> void _M_insert_range(_InputIterator __first, _InputIterator __last, const _NodeGetter&, true_type); template<typename _InputIterator, typename _NodeGetter> void _M_insert_range(_InputIterator __first, _InputIterator __last, const _NodeGetter&, false_type); public: __ireturn_type insert(const value_type& __v) { __hashtable& __h = _M_conjure_hashtable(); __node_gen_type __node_gen(__h); return __h._M_insert(__v, __node_gen, __unique_keys()); } iterator insert(const_iterator __hint, const value_type& __v) { __hashtable& __h = _M_conjure_hashtable(); __node_gen_type __node_gen(__h); return __h._M_insert(__hint, __v, __node_gen, __unique_keys()); } void insert(initializer_list<value_type> __l) { this->insert(__l.begin(), __l.end()); } template<typename _InputIterator> void insert(_InputIterator __first, _InputIterator __last) { __hashtable& __h = _M_conjure_hashtable(); __node_gen_type __node_gen(__h); return _M_insert_range(__first, __last, __node_gen, __unique_keys()); } }; template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> template<typename _InputIterator, typename _NodeGetter> void _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>:: _M_insert_range(_InputIterator __first, _InputIterator __last, const _NodeGetter& __node_gen, true_type) { size_type __n_elt = __detail::__distance_fw(__first, __last); if (__n_elt == 0) return; __hashtable& __h = _M_conjure_hashtable(); for (; __first != __last; ++__first) { if (__h._M_insert(__first, __node_gen, __unique_keys(), __n_elt).second) __n_elt = 1; else if (__n_elt != 1) --__n_elt; } } template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> template<typename _InputIterator, typename _NodeGetter> void _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>:: _M_insert_range(_InputIterator __first, _InputIterator __last, const _NodeGetter& __node_gen, false_type) { using __rehash_type = typename __hashtable::__rehash_type; using __rehash_state = typename __hashtable::__rehash_state; using pair_type = std::pair<bool, std::size_t>; size_type __n_elt = __detail::__distance_fw(__first, __last); if (__n_elt == 0) return; __hashtable& __h = _M_conjure_hashtable(); __rehash_type& __rehash = __h._M_rehash_policy; const __rehash_state& __saved_state = __rehash._M_state(); pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count, __h._M_element_count, __n_elt); if (__do_rehash.first) __h._M_rehash(__do_rehash.second, __saved_state); for (; __first != __last; ++__first) __h._M_insert(__first, __node_gen, __unique_keys()); } /* * Primary class template _Insert. * * Defines @c insert member functions that depend on _Hashtable policies, * via partial specializations. / template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits, bool _Constant_iterators = _Traits::__constant_iterators::value> struct _Insert; /// Specialization. template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true> : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits> { using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>; using value_type = typename __base_type::value_type; using iterator = typename __base_type::iterator; using const_iterator = typename __base_type::const_iterator; using __unique_keys = typename __base_type::__unique_keys; using __ireturn_type = typename __hashtable_base::__ireturn_type; using __hashtable = typename __base_type::__hashtable; using __node_gen_type = typename __base_type::__node_gen_type; using __base_type::insert; __ireturn_type insert(value_type&& __v) { __hashtable& __h = this->_M_conjure_hashtable(); __node_gen_type __node_gen(__h); return __h._M_insert(std::move(__v), __node_gen, __unique_keys()); } iterator insert(const_iterator __hint, value_type&& __v) { __hashtable& __h = this->_M_conjure_hashtable(); __node_gen_type __node_gen(__h); return __h._M_insert(__hint, std::move(__v), __node_gen, __unique_keys()); } }; /// Specialization. template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, false> : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits> { using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; using value_type = typename __base_type::value_type; using iterator = typename __base_type::iterator; using const_iterator = typename __base_type::const_iterator; using __unique_keys = typename __base_type::__unique_keys; using __hashtable = typename __base_type::__hashtable; using __ireturn_type = typename __base_type::__ireturn_type; using __base_type::insert; template<typename _Pair> using __is_cons = std::is_constructible<value_type, _Pair&&>; template<typename _Pair> using _IFcons = std::enable_if<__is_cons<_Pair>::value>; template<typename _Pair> using _IFconsp = typename _IFcons<_Pair>::type; template<typename _Pair, typename = _IFconsp<_Pair>> __ireturn_type insert(_Pair&& __v) { __hashtable& __h = this->_M_conjure_hashtable(); return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v)); } template<typename _Pair, typename = _IFconsp<_Pair>> iterator insert(const_iterator __hint, _Pair&& __v) { __hashtable& __h = this->_M_conjure_hashtable(); return __h._M_emplace(__hint, __unique_keys(), std::forward<_Pair>(__v)); } }; template<typename _Policy> using __has_load_factor = typename _Policy::__has_load_factor; /* * Primary class template _Rehash_base. * * Give hashtable the max_load_factor functions and reserve iff the * rehash policy supports it. / template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits, typename = __detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>> struct _Rehash_base; /// Specialization when rehash policy doesn't provide load factor management. template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, std::false_type> { }; /// Specialization when rehash policy provide load factor management. template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, std::true_type> { using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; float max_load_factor() const noexcept { const __hashtable __this = static_cast<const __hashtable>(this); return __this->__rehash_policy().max_load_factor(); } void max_load_factor(float __z) { __hashtable __this = static_cast<__hashtable>(this); __this->__rehash_policy(_RehashPolicy(__z)); } void reserve(std::size_t __n) { __hashtable __this = static_cast<__hashtable>(this); __this->rehash(__builtin_ceil(__n / max_load_factor())); } }; /* * Primary class template _Hashtable_ebo_helper. * * Helper class using EBO when it is not forbidden (the type is not * final) and when it is worth it (the type is empty.) / template<int _Nm, typename _Tp, bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)> struct _Hashtable_ebo_helper; /// Specialization using EBO. template<int _Nm, typename _Tp> struct _Hashtable_ebo_helper<_Nm, _Tp, true> : private _Tp { _Hashtable_ebo_helper() = default; template<typename _OtherTp> _Hashtable_ebo_helper(_OtherTp&& __tp) : _Tp(std::forward<_OtherTp>(__tp)) { } static const _Tp& _S_cget(const _Hashtable_ebo_helper& __eboh) { return static_cast<const _Tp&>(__eboh); } static _Tp& _S_get(_Hashtable_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); } }; /// Specialization not using EBO. template<int _Nm, typename _Tp> struct _Hashtable_ebo_helper<_Nm, _Tp, false> { _Hashtable_ebo_helper() = default; template<typename _OtherTp> _Hashtable_ebo_helper(_OtherTp&& __tp) : _M_tp(std::forward<_OtherTp>(__tp)) { } static const _Tp& _S_cget(const _Hashtable_ebo_helper& __eboh) { return __eboh._M_tp; } static _Tp& _S_get(_Hashtable_ebo_helper& __eboh) { return __eboh._M_tp; } private: _Tp _M_tp; }; /* * Primary class template _Local_iterator_base. * * Base class for local iterators, used to iterate within a bucket * but not between buckets. / template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash, bool __cache_hash_code> struct _Local_iterator_base; /* * Primary class template _Hash_code_base. * * Encapsulates two policy issues that aren't quite orthogonal. * (1) the difference between using a ranged hash function and using * the combination of a hash function and a range-hashing function. * In the former case we don't have such things as hash codes, so * we have a dummy type as placeholder. * (2) Whether or not we cache hash codes. Caching hash codes is * meaningless if we have a ranged hash function. * * We also put the key extraction objects here, for convenience. * Each specialization derives from one or more of the template * parameters to benefit from Ebo. This is important as this type * is inherited in some cases by the _Local_iterator_base type used * to implement local_iterator and const_local_iterator. As with * any iterator type we prefer to make it as small as possible. * * Primary template is unused except as a hook for specializations. / template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash, bool __cache_hash_code> struct _Hash_code_base; /// Specialization: ranged hash function, no caching hash codes. H1 /// and H2 are provided but ignored. We define a dummy hash code type. template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash> struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false> : private _Hashtable_ebo_helper<0, _ExtractKey>, private _Hashtable_ebo_helper<1, _Hash> { private: using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>; using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>; protected: typedef void __hash_code; typedef _Hash_node<_Value, false> __node_type; // We need the default constructor for the local iterators and _Hashtable // default constructor. _Hash_code_base() = default; _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&, const _Hash& __h) : __ebo_extract_key(__ex), __ebo_hash(__h) { } __hash_code _M_hash_code(const _Key& __key) const { return 0; } std::size_t _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const { return _M_ranged_hash()(__k, __n); } std::size_t _M_bucket_index(const __node_type* __p, std::size_t __n) const noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(), (std::size_t)0)) ) { return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); } void _M_store_code(__node_type, __hash_code) const { } void _M_copy_code(__node_type, const __node_type) const { } void _M_swap(_Hash_code_base& __x) { std::swap(_M_extract(), __x._M_extract()); std::swap(_M_ranged_hash(), __x._M_ranged_hash()); } const _ExtractKey& _M_extract() const { return __ebo_extract_key::_S_cget(this); } _ExtractKey& _M_extract() { return __ebo_extract_key::_S_get(this); } const _Hash& _M_ranged_hash() const { return __ebo_hash::_S_cget(this); } _Hash& _M_ranged_hash() { return __ebo_hash::_S_get(this); } }; // No specialization for ranged hash function while caching hash codes. // That combination is meaningless, and trying to do it is an error. /// Specialization: ranged hash function, cache hash codes. This /// combination is meaningless, so we provide only a declaration /// and no definition. template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash> struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>; /// Specialization: hash function and range-hashing function, no /// caching of hash codes. /// Provides typedef and accessor required by C++ 11. template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2> struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Default_ranged_hash, false> : private _Hashtable_ebo_helper<0, _ExtractKey>, private _Hashtable_ebo_helper<1, _H1>, private _Hashtable_ebo_helper<2, _H2> { private: using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>; using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>; using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>; // Gives the local iterator implementation access to _M_bucket_index(). friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Default_ranged_hash, false>; public: typedef _H1 hasher; hasher hash_function() const { return _M_h1(); } protected: typedef std::size_t __hash_code; typedef _Hash_node<_Value, false> __node_type; // We need the default constructor for the local iterators and _Hashtable // default constructor. _Hash_code_base() = default; _Hash_code_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2, const _Default_ranged_hash&) : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { } __hash_code _M_hash_code(const _Key& __k) const { static_assert(__is_invocable<const _H1&, const _Key&>{}, "hash function must be invocable with an argument of key type"); return _M_h1()(__k); } std::size_t _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const { return _M_h2()(__c, __n); } std::size_t _M_bucket_index(const __node_type __p, std::size_t __n) const noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>())) && noexcept(declval<const _H2&>()((__hash_code)0, (std::size_t)0)) ) { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); } void _M_store_code(__node_type, __hash_code) const { } void _M_copy_code(__node_type, const __node_type) const { } void _M_swap(_Hash_code_base& __x) { std::swap(_M_extract(), __x._M_extract()); std::swap(_M_h1(), __x._M_h1()); std::swap(_M_h2(), __x._M_h2()); } const _ExtractKey& _M_extract() const { return __ebo_extract_key::_S_cget(this); } _ExtractKey& _M_extract() { return __ebo_extract_key::_S_get(this); } const _H1& _M_h1() const { return __ebo_h1::_S_cget(this); } _H1& _M_h1() { return __ebo_h1::_S_get(this); } const _H2& _M_h2() const { return __ebo_h2::_S_cget(this); } _H2& _M_h2() { return __ebo_h2::_S_get(this); } }; /// Specialization: hash function and range-hashing function, /// caching hash codes. H is provided but ignored. Provides /// typedef and accessor required by C++ 11. template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2> struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Default_ranged_hash, true> : private _Hashtable_ebo_helper<0, _ExtractKey>, private _Hashtable_ebo_helper<1, _H1>, private _Hashtable_ebo_helper<2, _H2> { private: // Gives the local iterator implementation access to _M_h2(). friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Default_ranged_hash, true>; using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>; using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>; using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>; public: typedef _H1 hasher; hasher hash_function() const { return _M_h1(); } protected: typedef std::size_t __hash_code; typedef _Hash_node<_Value, true> __node_type; // We need the default constructor for _Hashtable default constructor. _Hash_code_base() = default; _Hash_code_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2, const _Default_ranged_hash&) : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { } __hash_code _M_hash_code(const _Key& __k) const { static_assert(__is_invocable<const _H1&, const _Key&>{}, "hash function must be invocable with an argument of key type"); return _M_h1()(__k); } std::size_t _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const { return _M_h2()(__c, __n); } std::size_t _M_bucket_index(const __node_type __p, std::size_t __n) const noexcept( noexcept(declval<const _H2&>()((__hash_code)0, (std::size_t)0)) ) { return _M_h2()(__p->_M_hash_code, __n); } void _M_store_code(__node_type* __n, __hash_code __c) const { __n->_M_hash_code = __c; } void _M_copy_code(__node_type* __to, const __node_type* __from) const { __to->_M_hash_code = __from->_M_hash_code; } void _M_swap(_Hash_code_base& __x) { std::swap(_M_extract(), __x._M_extract()); std::swap(_M_h1(), __x._M_h1()); std::swap(_M_h2(), __x._M_h2()); } const _ExtractKey& _M_extract() const { return __ebo_extract_key::_S_cget(this); } _ExtractKey& _M_extract() { return __ebo_extract_key::_S_get(this); } const _H1& _M_h1() const { return __ebo_h1::_S_cget(this); } _H1& _M_h1() { return __ebo_h1::_S_get(this); } const _H2& _M_h2() const { return __ebo_h2::_S_cget(this); } _H2& _M_h2() { return __ebo_h2::_S_get(this); } }; /** * Primary class template _Equal_helper. * / template <typename _Key, typename _Value, typename _ExtractKey, typename _Equal, typename _HashCodeType, bool __cache_hash_code> struct _Equal_helper; /// Specialization. template<typename _Key, typename _Value, typename _ExtractKey, typename _Equal, typename _HashCodeType> struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true> { static bool _S_equals(const _Equal& __eq, const _ExtractKey& __extract, const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true> __n) { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); } }; /// Specialization. template<typename _Key, typename _Value, typename _ExtractKey, typename _Equal, typename _HashCodeType> struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false> { static bool _S_equals(const _Equal& __eq, const _ExtractKey& __extract, const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n) { return __eq(__k, __extract(__n->_M_v())); } }; /// Partial specialization used when nodes contain a cached hash code. template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash> struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true> : private _Hashtable_ebo_helper<0, _H2> { protected: using __base_type = _Hashtable_ebo_helper<0, _H2>; using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>; _Local_iterator_base() = default; _Local_iterator_base(const __hash_code_base& __base, _Hash_node<_Value, true>* __p, std::size_t __bkt, std::size_t __bkt_count) : __base_type(__base._M_h2()), _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { } void _M_incr() { _M_cur = _M_cur->_M_next(); if (_M_cur) { std::size_t __bkt = __base_type::_S_get(this)(_M_cur->_M_hash_code, _M_bucket_count); if (__bkt != _M_bucket) _M_cur = nullptr; } } _Hash_node<_Value, true> _M_cur; std::size_t _M_bucket; std::size_t _M_bucket_count; public: const void* _M_curr() const { return _M_cur; } // for equality ops std::size_t _M_get_bucket() const { return _M_bucket; } // for debug mode }; // Uninitialized storage for a _Hash_code_base. // This type is DefaultConstructible and Assignable even if the // _Hash_code_base type isn't, so that _Local_iterator_base<..., false> // can be DefaultConstructible and Assignable. template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value> struct _Hash_code_storage { __gnu_cxx::__aligned_buffer<_Tp> _M_storage; _Tp* _M_h() { return _M_storage._M_ptr(); } const _Tp* _M_h() const { return _M_storage._M_ptr(); } }; // Empty partial specialization for empty _Hash_code_base types. template<typename _Tp> struct _Hash_code_storage<_Tp, true> { static_assert( std::is_empty<_Tp>::value, "Type must be empty" ); // As _Tp is an empty type there will be no bytes written/read through // the cast pointer, so no strict-aliasing violation. _Tp* _M_h() { return reinterpret_cast<_Tp>(this); } const _Tp _M_h() const { return reinterpret_cast<const _Tp>(this); } }; template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash> using __hash_code_for_local_iter = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>>; // Partial specialization used when hash codes are not cached template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash> struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false> : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash> { protected: using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>; _Local_iterator_base() : _M_bucket_count(-1) { } _Local_iterator_base(const __hash_code_base& __base, _Hash_node<_Value, false> __p, std::size_t __bkt, std::size_t __bkt_count) : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { _M_init(__base); } ~_Local_iterator_base() { if (_M_bucket_count != -1) _M_destroy(); } _Local_iterator_base(const _Local_iterator_base& __iter) : _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket), _M_bucket_count(__iter._M_bucket_count) { if (_M_bucket_count != -1) _M_init(__iter._M_h()); } _Local_iterator_base& operator=(const _Local_iterator_base& __iter) { if (_M_bucket_count != -1) _M_destroy(); _M_cur = __iter._M_cur; _M_bucket = __iter._M_bucket; _M_bucket_count = __iter._M_bucket_count; if (_M_bucket_count != -1) _M_init(__iter._M_h()); return this; } void _M_incr() { _M_cur = _M_cur->_M_next(); if (_M_cur) { std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur, _M_bucket_count); if (__bkt != _M_bucket) _M_cur = nullptr; } } _Hash_node<_Value, false> _M_cur; std::size_t _M_bucket; std::size_t _M_bucket_count; void _M_init(const __hash_code_base& __base) { ::new(this->_M_h()) __hash_code_base(__base); } void _M_destroy() { this->_M_h()->~__hash_code_base(); } public: const void* _M_curr() const { return _M_cur; } // for equality ops and debug mode std::size_t _M_get_bucket() const { return _M_bucket; } // for debug mode }; template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash, bool __cache> inline bool operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache>& __x, const _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache>& __y) { return __x._M_curr() == __y._M_curr(); } template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash, bool __cache> inline bool operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache>& __x, const _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache>& __y) { return __x._M_curr() != __y._M_curr(); } /// local iterators template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash, bool __constant_iterators, bool __cache> struct _Local_iterator : public _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache> { private: using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache>; using __hash_code_base = typename __base_type::__hash_code_base; public: typedef _Value value_type; typedef typename std::conditional<__constant_iterators, const _Value, _Value>::type pointer; typedef typename std::conditional<__constant_iterators, const _Value&, _Value&>::type reference; typedef std::ptrdiff_t difference_type; typedef std::forward_iterator_tag iterator_category; _Local_iterator() = default; _Local_iterator(const __hash_code_base& __base, _Hash_node<_Value, __cache>* __p, std::size_t __bkt, std::size_t __bkt_count) : __base_type(__base, __p, __bkt, __bkt_count) { } reference operator() const { return this->_M_cur->_M_v(); } pointer operator->() const { return this->_M_cur->_M_valptr(); } _Local_iterator& operator++() { this->_M_incr(); return this; } _Local_iterator operator++(int) { _Local_iterator __tmp(this); this->_M_incr(); return __tmp; } }; /// local const_iterators template<typename _Key, typename _Value, typename _ExtractKey, typename _H1, typename _H2, typename _Hash, bool __constant_iterators, bool __cache> struct _Local_const_iterator : public _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache> { private: using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __cache>; using __hash_code_base = typename __base_type::__hash_code_base; public: typedef _Value value_type; typedef const _Value pointer; typedef const _Value& reference; typedef std::ptrdiff_t difference_type; typedef std::forward_iterator_tag iterator_category; _Local_const_iterator() = default; _Local_const_iterator(const __hash_code_base& __base, _Hash_node<_Value, __cache>* __p, std::size_t __bkt, std::size_t __bkt_count) : __base_type(__base, __p, __bkt, __bkt_count) { } _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __constant_iterators, __cache>& __x) : __base_type(__x) { } reference operator() const { return this->_M_cur->_M_v(); } pointer operator->() const { return this->_M_cur->_M_valptr(); } _Local_const_iterator& operator++() { this->_M_incr(); return this; } _Local_const_iterator operator++(int) { _Local_const_iterator __tmp(this); this->_M_incr(); return __tmp; } }; /* * Primary class template _Hashtable_base. * * Helper class adding management of _Equal functor to * _Hash_code_base type. * * Base class templates are: * - __detail::_Hash_code_base * - __detail::_Hashtable_ebo_helper / template<typename _Key, typename _Value, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _Traits> struct _Hashtable_base : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, _Traits::__hash_cached::value>, private _Hashtable_ebo_helper<0, _Equal> { public: typedef _Key key_type; typedef _Value value_type; typedef _Equal key_equal; typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; using __traits_type = _Traits; using __hash_cached = typename __traits_type::__hash_cached; using __constant_iterators = typename __traits_type::__constant_iterators; using __unique_keys = typename __traits_type::__unique_keys; using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, __hash_cached::value>; using __hash_code = typename __hash_code_base::__hash_code; using __node_type = typename __hash_code_base::__node_type; using iterator = __detail::_Node_iterator<value_type, __constant_iterators::value, __hash_cached::value>; using const_iterator = __detail::_Node_const_iterator<value_type, __constant_iterators::value, __hash_cached::value>; using local_iterator = __detail::_Local_iterator<key_type, value_type, _ExtractKey, _H1, _H2, _Hash, __constant_iterators::value, __hash_cached::value>; using const_local_iterator = __detail::_Local_const_iterator<key_type, value_type, _ExtractKey, _H1, _H2, _Hash, __constant_iterators::value, __hash_cached::value>; using __ireturn_type = typename std::conditional<__unique_keys::value, std::pair<iterator, bool>, iterator>::type; private: using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>; using _EqualHelper = _Equal_helper<_Key, _Value, _ExtractKey, _Equal, __hash_code, __hash_cached::value>; protected: _Hashtable_base() = default; _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2, const _Hash& __hash, const _Equal& __eq) : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq) { } bool _M_equals(const _Key& __k, __hash_code __c, __node_type __n) const { static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{}, "key equality predicate must be invocable with two arguments of " "key type"); return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(), __k, __c, __n); } void _M_swap(_Hashtable_base& __x) { __hash_code_base::_M_swap(__x); std::swap(_M_eq(), __x._M_eq()); } const _Equal& _M_eq() const { return _EqualEBO::_S_cget(this); } _Equal& _M_eq() { return _EqualEBO::_S_get(this); } }; /** * struct _Equality_base. * * Common types and functions for class _Equality. / struct _Equality_base { protected: template<typename _Uiterator> static bool _S_is_permutation(_Uiterator, _Uiterator, _Uiterator); }; // See std::is_permutation in N3068. template<typename _Uiterator> bool _Equality_base:: _S_is_permutation(_Uiterator __first1, _Uiterator __last1, _Uiterator __first2) { for (; __first1 != __last1; ++__first1, ++__first2) if (!(__first1 == __first2)) break; if (__first1 == __last1) return true; _Uiterator __last2 = __first2; std::advance(__last2, std::distance(__first1, __last1)); for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1) { _Uiterator __tmp = __first1; while (__tmp != __it1 && !bool(__tmp == __it1)) ++__tmp; // We've seen this one before. if (__tmp != __it1) continue; std::ptrdiff_t __n2 = 0; for (__tmp = __first2; __tmp != __last2; ++__tmp) if (__tmp == __it1) ++__n2; if (!__n2) return false; std::ptrdiff_t __n1 = 0; for (__tmp = __it1; __tmp != __last1; ++__tmp) if (__tmp == __it1) ++__n1; if (__n1 != __n2) return false; } return true; } /* * Primary class template _Equality. * * This is for implementing equality comparison for unordered * containers, per N3068, by John Lakos and Pablo Halpern. * Algorithmically, we follow closely the reference implementations * therein. / template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits, bool _Unique_keys = _Traits::__unique_keys::value> struct _Equality; /// Specialization. template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true> { using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; bool _M_equal(const __hashtable&) const; }; template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> bool _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, true>:: _M_equal(const __hashtable& __other) const { const __hashtable __this = static_cast<const __hashtable>(this); if (__this->size() != __other.size()) return false; for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx) { const auto __ity = __other.find(_ExtractKey()(__itx)); if (__ity == __other.end() \|\| !bool(__ity == __itx)) return false; } return true; } /// Specialization. template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, false> : public _Equality_base { using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>; bool _M_equal(const __hashtable&) const; }; template<typename _Key, typename _Value, typename _Alloc, typename _ExtractKey, typename _Equal, typename _H1, typename _H2, typename _Hash, typename _RehashPolicy, typename _Traits> bool _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits, false>:: _M_equal(const __hashtable& __other) const { const __hashtable* __this = static_cast<const __hashtable>(this); if (__this->size() != __other.size()) return false; for (auto __itx = __this->begin(); __itx != __this->end();) { const auto __xrange = __this->equal_range(_ExtractKey()(__itx)); const auto __yrange = __other.equal_range(_ExtractKey()(__itx)); if (std::distance(__xrange.first, __xrange.second) != std::distance(__yrange.first, __yrange.second)) return false; if (!_S_is_permutation(__xrange.first, __xrange.second, __yrange.first)) return false; __itx = __xrange.second; } return true; } /* * This type deals with all allocation and keeps an allocator instance through * inheritance to benefit from EBO when possible. / template<typename _NodeAlloc> struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc> { private: using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>; public: using __node_type = typename _NodeAlloc::value_type; using __node_alloc_type = _NodeAlloc; // Use __gnu_cxx to benefit from _S_always_equal and al. using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>; using __value_alloc_traits = typename __node_alloc_traits::template rebind_traits<typename __node_type::value_type>; using __node_base = __detail::_Hash_node_base; using __bucket_type = __node_base; using __bucket_alloc_type = __alloc_rebind<__node_alloc_type, __bucket_type>; using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>; _Hashtable_alloc() = default; _Hashtable_alloc(const _Hashtable_alloc&) = default; _Hashtable_alloc(_Hashtable_alloc&&) = default; template<typename _Alloc> _Hashtable_alloc(_Alloc&& __a) : __ebo_node_alloc(std::forward<_Alloc>(__a)) { } __node_alloc_type& _M_node_allocator() { return __ebo_node_alloc::_S_get(this); } const __node_alloc_type& _M_node_allocator() const { return __ebo_node_alloc::_S_cget(this); } template<typename... _Args> __node_type* _M_allocate_node(_Args&&... __args); void _M_deallocate_node(__node_type* __n); // Deallocate the linked list of nodes pointed to by __n void _M_deallocate_nodes(__node_type* __n); __bucket_type* _M_allocate_buckets(std::size_t __n); void _M_deallocate_buckets(__bucket_type, std::size_t __n); }; // Definitions of class template _Hashtable_alloc's out-of-line member // functions. template<typename _NodeAlloc> template<typename... _Args> typename _Hashtable_alloc<_NodeAlloc>::__node_type _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args) { auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1); __node_type* __n = std::__to_address(__nptr); __try { ::new ((void)__n) __node_type; __node_alloc_traits::construct(_M_node_allocator(), __n->_M_valptr(), std::forward<_Args>(__args)...); return __n; } __catch(...) { __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1); __throw_exception_again; } } template<typename _NodeAlloc> void _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type __n) { typedef typename __node_alloc_traits::pointer _Ptr; auto __ptr = std::pointer_traits<_Ptr>::pointer_to(__n); __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr()); __n->~__node_type(); __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1); } template<typename _NodeAlloc> void _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type __n) { while (__n) { __node_type* __tmp = __n; __n = __n->_M_next(); _M_deallocate_node(__tmp); } } template<typename _NodeAlloc> typename _Hashtable_alloc<_NodeAlloc>::__bucket_type* _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n) { __bucket_alloc_type __alloc(_M_node_allocator()); auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n); __bucket_type* __p = std::__to_address(__ptr); __builtin_memset(__p, 0, __n * sizeof(__bucket_type)); return __p; } template<typename _NodeAlloc> void _Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts, std::size_t __n) { typedef typename __bucket_alloc_traits::pointer _Ptr; auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts); __bucket_alloc_type __alloc(_M_node_allocator()); __bucket_alloc_traits::deallocate(__alloc, __ptr, __n); } //@} hashtable-detail } // namespace __detail _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // _HASHTABLE_POLICY_H Back

Edit File : hashtable_policy.h | Size : 66.38 KB

// Internal policy header for unordered_set and unordered_map -*- C++ -*-

// Copyright (C) 2010-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library 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 3, or (at your option)
// any later version.

// This library 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/hashtable_policy.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly.
 *  @headername{unordered_map,unordered_set}
 */

#ifndef _HASHTABLE_POLICY_H
#define _HASHTABLE_POLICY_H 1

#include <tuple>		// for std::tuple, std::forward_as_tuple
#include <cstdint>		// for std::uint_fast64_t
#include <bits/stl_algobase.h>	// for std::min.

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace __detail
{
  /**
   *  @defgroup hashtable-detail Base and Implementation Classes
   *  @ingroup unordered_associative_containers
   *  @{
   */
  template<typename _Key, typename _Value,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash, typename _Traits>
    struct _Hashtable_base;

// Helper function: return distance(first, last) for forward
  // iterators, or 0/1 for input iterators.
  template<class _Iterator>
    inline typename std::iterator_traits<_Iterator>::difference_type
    __distance_fw(_Iterator __first, _Iterator __last,
		  std::input_iterator_tag)
    { return __first != __last ? 1 : 0; }

template<class _Iterator>
    inline typename std::iterator_traits<_Iterator>::difference_type
    __distance_fw(_Iterator __first, _Iterator __last,
		  std::forward_iterator_tag)
    { return std::distance(__first, __last); }

template<class _Iterator>
    inline typename std::iterator_traits<_Iterator>::difference_type
    __distance_fw(_Iterator __first, _Iterator __last)
    { return __distance_fw(__first, __last,
			   std::__iterator_category(__first)); }

struct _Identity
  {
    template<typename _Tp>
      _Tp&&
      operator()(_Tp&& __x) const
      { return std::forward<_Tp>(__x); }
  };

struct _Select1st
  {
    template<typename _Tp>
      auto
      operator()(_Tp&& __x) const
      -> decltype(std::get<0>(std::forward<_Tp>(__x)))
      { return std::get<0>(std::forward<_Tp>(__x)); }
  };

template<typename _NodeAlloc>
    struct _Hashtable_alloc;

// Functor recycling a pool of nodes and using allocation once the pool is
  // empty.
  template<typename _NodeAlloc>
    struct _ReuseOrAllocNode
    {
    private:
      using __node_alloc_type = _NodeAlloc;
      using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
      using __node_alloc_traits =
	typename __hashtable_alloc::__node_alloc_traits;
      using __node_type = typename __hashtable_alloc::__node_type;

public:
      _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
	: _M_nodes(__nodes), _M_h(__h) { }
      _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;

~_ReuseOrAllocNode()
      { _M_h._M_deallocate_nodes(_M_nodes); }

template<typename _Arg>
	__node_type*
	operator()(_Arg&& __arg) const
	{
	  if (_M_nodes)
	    {
	      __node_type* __node = _M_nodes;
	      _M_nodes = _M_nodes->_M_next();
	      __node->_M_nxt = nullptr;
	      auto& __a = _M_h._M_node_allocator();
	      __node_alloc_traits::destroy(__a, __node->_M_valptr());
	      __try
		{
		  __node_alloc_traits::construct(__a, __node->_M_valptr(),
						 std::forward<_Arg>(__arg));
		}
	      __catch(...)
		{
		  __node->~__node_type();
		  __node_alloc_traits::deallocate(__a, __node, 1);
		  __throw_exception_again;
		}
	      return __node;
	    }
	  return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
	}

private:
      mutable __node_type* _M_nodes;
      __hashtable_alloc& _M_h;
    };

// Functor similar to the previous one but without any pool of nodes to
  // recycle.
  template<typename _NodeAlloc>
    struct _AllocNode
    {
    private:
      using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
      using __node_type = typename __hashtable_alloc::__node_type;

public:
      _AllocNode(__hashtable_alloc& __h)
	: _M_h(__h) { }

template<typename _Arg>
	__node_type*
	operator()(_Arg&& __arg) const
	{ return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }

private:
      __hashtable_alloc& _M_h;
    };

// Auxiliary types used for all instantiations of _Hashtable nodes
  // and iterators.

/**
   *  struct _Hashtable_traits
   *
   *  Important traits for hash tables.
   *
   *  @tparam _Cache_hash_code  Boolean value. True if the value of
   *  the hash function is stored along with the value. This is a
   *  time-space tradeoff.  Storing it may improve lookup speed by
   *  reducing the number of times we need to call the _Equal
   *  function.
   *
   *  @tparam _Constant_iterators  Boolean value. True if iterator and
   *  const_iterator are both constant iterator types. This is true
   *  for unordered_set and unordered_multiset, false for
   *  unordered_map and unordered_multimap.
   *
   *  @tparam _Unique_keys  Boolean value. True if the return value
   *  of _Hashtable::count(k) is always at most one, false if it may
   *  be an arbitrary number. This is true for unordered_set and
   *  unordered_map, false for unordered_multiset and
   *  unordered_multimap.
   */
  template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
    struct _Hashtable_traits
    {
      using __hash_cached = __bool_constant<_Cache_hash_code>;
      using __constant_iterators = __bool_constant<_Constant_iterators>;
      using __unique_keys = __bool_constant<_Unique_keys>;
    };

/**
   *  struct _Hash_node_base
   *
   *  Nodes, used to wrap elements stored in the hash table.  A policy
   *  template parameter of class template _Hashtable controls whether
   *  nodes also store a hash code. In some cases (e.g. strings) this
   *  may be a performance win.
   */
  struct _Hash_node_base
  {
    _Hash_node_base* _M_nxt;

_Hash_node_base() noexcept : _M_nxt() { }

_Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
  };

/**
   *  struct _Hash_node_value_base
   *
   *  Node type with the value to store.
   */
  template<typename _Value>
    struct _Hash_node_value_base : _Hash_node_base
    {
      typedef _Value value_type;

__gnu_cxx::__aligned_buffer<_Value> _M_storage;

_Value*
      _M_valptr() noexcept
      { return _M_storage._M_ptr(); }

const _Value*
      _M_valptr() const noexcept
      { return _M_storage._M_ptr(); }

_Value&
      _M_v() noexcept
      { return *_M_valptr(); }

const _Value&
      _M_v() const noexcept
      { return *_M_valptr(); }
    };

/**
   *  Primary template struct _Hash_node.
   */
  template<typename _Value, bool _Cache_hash_code>
    struct _Hash_node;

/**
   *  Specialization for nodes with caches, struct _Hash_node.
   *
   *  Base class is __detail::_Hash_node_value_base.
   */
  template<typename _Value>
    struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value>
    {
      std::size_t  _M_hash_code;

_Hash_node*
      _M_next() const noexcept
      { return static_cast<_Hash_node*>(this->_M_nxt); }
    };

/**
   *  Specialization for nodes without caches, struct _Hash_node.
   *
   *  Base class is __detail::_Hash_node_value_base.
   */
  template<typename _Value>
    struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value>
    {
      _Hash_node*
      _M_next() const noexcept
      { return static_cast<_Hash_node*>(this->_M_nxt); }
    };

/// Base class for node iterators.
  template<typename _Value, bool _Cache_hash_code>
    struct _Node_iterator_base
    {
      using __node_type = _Hash_node<_Value, _Cache_hash_code>;

__node_type*  _M_cur;

_Node_iterator_base(__node_type* __p) noexcept
      : _M_cur(__p) { }

void
      _M_incr() noexcept
      { _M_cur = _M_cur->_M_next(); }
    };

template<typename _Value, bool _Cache_hash_code>
    inline bool
    operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
	       const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
    noexcept
    { return __x._M_cur == __y._M_cur; }

template<typename _Value, bool _Cache_hash_code>
    inline bool
    operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
	       const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
    noexcept
    { return __x._M_cur != __y._M_cur; }

/// Node iterators, used to iterate through all the hashtable.
  template<typename _Value, bool __constant_iterators, bool __cache>
    struct _Node_iterator
    : public _Node_iterator_base<_Value, __cache>
    {
    private:
      using __base_type = _Node_iterator_base<_Value, __cache>;
      using __node_type = typename __base_type::__node_type;

public:
      typedef _Value					value_type;
      typedef std::ptrdiff_t				difference_type;
      typedef std::forward_iterator_tag			iterator_category;

using pointer = typename std::conditional<__constant_iterators,
						const _Value*, _Value*>::type;

using reference = typename std::conditional<__constant_iterators,
						  const _Value&, _Value&>::type;

_Node_iterator() noexcept
      : __base_type(0) { }

explicit
      _Node_iterator(__node_type* __p) noexcept
      : __base_type(__p) { }

reference
      operator*() const noexcept
      { return this->_M_cur->_M_v(); }

pointer
      operator->() const noexcept
      { return this->_M_cur->_M_valptr(); }

_Node_iterator&
      operator++() noexcept
      {
	this->_M_incr();
	return *this;
      }

_Node_iterator
      operator++(int) noexcept
      {
	_Node_iterator __tmp(*this);
	this->_M_incr();
	return __tmp;
      }
    };

/// Node const_iterators, used to iterate through all the hashtable.
  template<typename _Value, bool __constant_iterators, bool __cache>
    struct _Node_const_iterator
    : public _Node_iterator_base<_Value, __cache>
    {
    private:
      using __base_type = _Node_iterator_base<_Value, __cache>;
      using __node_type = typename __base_type::__node_type;

public:
      typedef _Value					value_type;
      typedef std::ptrdiff_t				difference_type;
      typedef std::forward_iterator_tag			iterator_category;

typedef const _Value*				pointer;
      typedef const _Value&				reference;

_Node_const_iterator() noexcept
      : __base_type(0) { }

explicit
      _Node_const_iterator(__node_type* __p) noexcept
      : __base_type(__p) { }

_Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
			   __cache>& __x) noexcept
      : __base_type(__x._M_cur) { }

reference
      operator*() const noexcept
      { return this->_M_cur->_M_v(); }

pointer
      operator->() const noexcept
      { return this->_M_cur->_M_valptr(); }

_Node_const_iterator&
      operator++() noexcept
      {
	this->_M_incr();
	return *this;
      }

_Node_const_iterator
      operator++(int) noexcept
      {
	_Node_const_iterator __tmp(*this);
	this->_M_incr();
	return __tmp;
      }
    };

// Many of class template _Hashtable's template parameters are policy
  // classes.  These are defaults for the policies.

/// Default range hashing function: use division to fold a large number
  /// into the range [0, N).
  struct _Mod_range_hashing
  {
    typedef std::size_t first_argument_type;
    typedef std::size_t second_argument_type;
    typedef std::size_t result_type;

result_type
    operator()(first_argument_type __num,
	       second_argument_type __den) const noexcept
    { return __num % __den; }
  };

/// Default ranged hash function H.  In principle it should be a
  /// function object composed from objects of type H1 and H2 such that
  /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
  /// h1 and h2.  So instead we'll just use a tag to tell class template
  /// hashtable to do that composition.
  struct _Default_ranged_hash { };

/// Default value for rehash policy.  Bucket size is (usually) the
  /// smallest prime that keeps the load factor small enough.
  struct _Prime_rehash_policy
  {
    using __has_load_factor = std::true_type;

_Prime_rehash_policy(float __z = 1.0) noexcept
    : _M_max_load_factor(__z), _M_next_resize(0) { }

float
    max_load_factor() const noexcept
    { return _M_max_load_factor; }

// Return a bucket size no smaller than n.
    std::size_t
    _M_next_bkt(std::size_t __n) const;

// Return a bucket count appropriate for n elements
    std::size_t
    _M_bkt_for_elements(std::size_t __n) const
    { return __builtin_ceil(__n / (long double)_M_max_load_factor); }

typedef std::size_t _State;

_State
    _M_state() const
    { return _M_next_resize; }

void
    _M_reset() noexcept
    { _M_next_resize = 0; }

void
    _M_reset(_State __state)
    { _M_next_resize = __state; }

static const std::size_t _S_growth_factor = 2;

float		_M_max_load_factor;
    mutable std::size_t	_M_next_resize;
  };

/// Range hashing function assuming that second arg is a power of 2.
  struct _Mask_range_hashing
  {
    typedef std::size_t first_argument_type;
    typedef std::size_t second_argument_type;
    typedef std::size_t result_type;

result_type
    operator()(first_argument_type __num,
	       second_argument_type __den) const noexcept
    { return __num & (__den - 1); }
  };

/// Compute closest power of 2.
  _GLIBCXX14_CONSTEXPR
  inline std::size_t
  __clp2(std::size_t __n) noexcept
  {
#if __SIZEOF_SIZE_T__ >= 8
    std::uint_fast64_t __x = __n;
#else
    std::uint_fast32_t __x = __n;
#endif
    // Algorithm from Hacker's Delight, Figure 3-3.
    __x = __x - 1;
    __x = __x | (__x >> 1);
    __x = __x | (__x >> 2);
    __x = __x | (__x >> 4);
    __x = __x | (__x >> 8);
    __x = __x | (__x >>16);
#if __SIZEOF_SIZE_T__ >= 8
    __x = __x | (__x >>32);
#endif
    return __x + 1;
  }

/// Rehash policy providing power of 2 bucket numbers. Avoids modulo
  /// operations.
  struct _Power2_rehash_policy
  {
    using __has_load_factor = std::true_type;

_Power2_rehash_policy(float __z = 1.0) noexcept
    : _M_max_load_factor(__z), _M_next_resize(0) { }

float
    max_load_factor() const noexcept
    { return _M_max_load_factor; }

// Return a bucket size no smaller than n (as long as n is not above the
    // highest power of 2).
    std::size_t
    _M_next_bkt(std::size_t __n) noexcept
    {
      const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
      const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
      std::size_t __res = __clp2(__n);

if (__res == __n)
	__res <<= 1;

if (__res == 0)
	__res = __max_bkt;

if (__res == __max_bkt)
	// Set next resize to the max value so that we never try to rehash again
	// as we already reach the biggest possible bucket number.
	// Note that it might result in max_load_factor not being respected.
	_M_next_resize = std::size_t(-1);
      else
	_M_next_resize
	  = __builtin_ceil(__res * (long double)_M_max_load_factor);

return __res;
    }

// Return a bucket count appropriate for n elements
    std::size_t
    _M_bkt_for_elements(std::size_t __n) const noexcept
    { return __builtin_ceil(__n / (long double)_M_max_load_factor); }

// __n_bkt is current bucket count, __n_elt is current element count,
    // and __n_ins is number of elements to be inserted.  Do we need to
    // increase bucket count?  If so, return make_pair(true, n), where n
    // is the new bucket count.  If not, return make_pair(false, 0).
    std::pair<bool, std::size_t>
    _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
		   std::size_t __n_ins) noexcept
    {
      if (__n_elt + __n_ins >= _M_next_resize)
	{
	  long double __min_bkts = (__n_elt + __n_ins)
					/ (long double)_M_max_load_factor;
	  if (__min_bkts >= __n_bkt)
	    return std::make_pair(true,
	      _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
						__n_bkt * _S_growth_factor)));

_M_next_resize
	    = __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
	  return std::make_pair(false, 0);
	}
      else
	return std::make_pair(false, 0);
    }

typedef std::size_t _State;

_State
    _M_state() const noexcept
    { return _M_next_resize; }

void
    _M_reset() noexcept
    { _M_next_resize = 0; }

void
    _M_reset(_State __state) noexcept
    { _M_next_resize = __state; }

static const std::size_t _S_growth_factor = 2;

float	_M_max_load_factor;
    std::size_t	_M_next_resize;
  };

// Base classes for std::_Hashtable.  We define these base classes
  // because in some cases we want to do different things depending on
  // the value of a policy class.  In some cases the policy class
  // affects which member functions and nested typedefs are defined;
  // we handle that by specializing base class templates.  Several of
  // the base class templates need to access other members of class
  // template _Hashtable, so we use a variant of the "Curiously
  // Recurring Template Pattern" (CRTP) technique.

/**
   *  Primary class template _Map_base.
   *
   *  If the hashtable has a value type of the form pair<T1, T2> and a
   *  key extraction policy (_ExtractKey) that returns the first part
   *  of the pair, the hashtable gets a mapped_type typedef.  If it
   *  satisfies those criteria and also has unique keys, then it also
   *  gets an operator[].
   */
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits,
	   bool _Unique_keys = _Traits::__unique_keys::value>
    struct _Map_base { };

/// Partial specialization, __unique_keys set to false.
  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
		     _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
    {
      using mapped_type = typename std::tuple_element<1, _Pair>::type;
    };

/// Partial specialization, __unique_keys set to true.
  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
		     _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
    {
    private:
      using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
							 _Select1st,
							_Equal, _H1, _H2, _Hash,
							  _Traits>;

using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
				     _Select1st, _Equal,
				     _H1, _H2, _Hash, _RehashPolicy, _Traits>;

using __hash_code = typename __hashtable_base::__hash_code;
      using __node_type = typename __hashtable_base::__node_type;

public:
      using key_type = typename __hashtable_base::key_type;
      using iterator = typename __hashtable_base::iterator;
      using mapped_type = typename std::tuple_element<1, _Pair>::type;

mapped_type&
      operator[](const key_type& __k);

mapped_type&
      operator[](key_type&& __k);

// _GLIBCXX_RESOLVE_LIB_DEFECTS
      // DR 761. unordered_map needs an at() member function.
      mapped_type&
      at(const key_type& __k);

const mapped_type&
      at(const key_type& __k) const;
    };

template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    auto
    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    operator[](const key_type& __k)
    -> mapped_type&
    {
      __hashtable* __h = static_cast<__hashtable*>(this);
      __hash_code __code = __h->_M_hash_code(__k);
      std::size_t __n = __h->_M_bucket_index(__k, __code);
      __node_type* __p = __h->_M_find_node(__n, __k, __code);

if (!__p)
	{
	  __p = __h->_M_allocate_node(std::piecewise_construct,
				      std::tuple<const key_type&>(__k),
				      std::tuple<>());
	  return __h->_M_insert_unique_node(__n, __code, __p)->second;
	}

return __p->_M_v().second;
    }

template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    auto
    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    operator[](key_type&& __k)
    -> mapped_type&
    {
      __hashtable* __h = static_cast<__hashtable*>(this);
      __hash_code __code = __h->_M_hash_code(__k);
      std::size_t __n = __h->_M_bucket_index(__k, __code);
      __node_type* __p = __h->_M_find_node(__n, __k, __code);

if (!__p)
	{
	  __p = __h->_M_allocate_node(std::piecewise_construct,
				      std::forward_as_tuple(std::move(__k)),
				      std::tuple<>());
	  return __h->_M_insert_unique_node(__n, __code, __p)->second;
	}

return __p->_M_v().second;
    }

template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    auto
    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    at(const key_type& __k)
    -> mapped_type&
    {
      __hashtable* __h = static_cast<__hashtable*>(this);
      __hash_code __code = __h->_M_hash_code(__k);
      std::size_t __n = __h->_M_bucket_index(__k, __code);
      __node_type* __p = __h->_M_find_node(__n, __k, __code);

if (!__p)
	__throw_out_of_range(__N("_Map_base::at"));
      return __p->_M_v().second;
    }

template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    auto
    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    at(const key_type& __k) const
    -> const mapped_type&
    {
      const __hashtable* __h = static_cast<const __hashtable*>(this);
      __hash_code __code = __h->_M_hash_code(__k);
      std::size_t __n = __h->_M_bucket_index(__k, __code);
      __node_type* __p = __h->_M_find_node(__n, __k, __code);

if (!__p)
	__throw_out_of_range(__N("_Map_base::at"));
      return __p->_M_v().second;
    }

/**
   *  Primary class template _Insert_base.
   *
   *  Defines @c insert member functions appropriate to all _Hashtables.
   */
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Insert_base
    {
    protected:
      using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
				     _Equal, _H1, _H2, _Hash,
				     _RehashPolicy, _Traits>;

using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
					       _Equal, _H1, _H2, _Hash,
					       _Traits>;

using value_type = typename __hashtable_base::value_type;
      using iterator = typename __hashtable_base::iterator;
      using const_iterator =  typename __hashtable_base::const_iterator;
      using size_type = typename __hashtable_base::size_type;

using __unique_keys = typename __hashtable_base::__unique_keys;
      using __ireturn_type = typename __hashtable_base::__ireturn_type;
      using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>;
      using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
      using __node_gen_type = _AllocNode<__node_alloc_type>;

__hashtable&
      _M_conjure_hashtable()
      { return *(static_cast<__hashtable*>(this)); }

template<typename _InputIterator, typename _NodeGetter>
	void
	_M_insert_range(_InputIterator __first, _InputIterator __last,
			const _NodeGetter&, true_type);

template<typename _InputIterator, typename _NodeGetter>
	void
	_M_insert_range(_InputIterator __first, _InputIterator __last,
			const _NodeGetter&, false_type);

public:
      __ireturn_type
      insert(const value_type& __v)
      {
	__hashtable& __h = _M_conjure_hashtable();
	__node_gen_type __node_gen(__h);
	return __h._M_insert(__v, __node_gen, __unique_keys());
      }

iterator
      insert(const_iterator __hint, const value_type& __v)
      {
	__hashtable& __h = _M_conjure_hashtable();
	__node_gen_type __node_gen(__h);	
	return __h._M_insert(__hint, __v, __node_gen, __unique_keys());
      }

void
      insert(initializer_list<value_type> __l)
      { this->insert(__l.begin(), __l.end()); }

template<typename _InputIterator>
	void
	insert(_InputIterator __first, _InputIterator __last)
	{
	  __hashtable& __h = _M_conjure_hashtable();
	  __node_gen_type __node_gen(__h);
	  return _M_insert_range(__first, __last, __node_gen, __unique_keys());
	}
    };

template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    template<typename _InputIterator, typename _NodeGetter>
      void
      _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
		    _RehashPolicy, _Traits>::
      _M_insert_range(_InputIterator __first, _InputIterator __last,
		      const _NodeGetter& __node_gen, true_type)
      {
	size_type __n_elt = __detail::__distance_fw(__first, __last);
	if (__n_elt == 0)
	  return;

__hashtable& __h = _M_conjure_hashtable();
	for (; __first != __last; ++__first)
	  {
	    if (__h._M_insert(*__first, __node_gen, __unique_keys(),
			      __n_elt).second)
	      __n_elt = 1;
	    else if (__n_elt != 1)
	      --__n_elt;
	  }
      }

template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    template<typename _InputIterator, typename _NodeGetter>
      void
      _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
		    _RehashPolicy, _Traits>::
      _M_insert_range(_InputIterator __first, _InputIterator __last,
		      const _NodeGetter& __node_gen, false_type)
      {
	using __rehash_type = typename __hashtable::__rehash_type;
	using __rehash_state = typename __hashtable::__rehash_state;
	using pair_type = std::pair<bool, std::size_t>;

size_type __n_elt = __detail::__distance_fw(__first, __last);
	if (__n_elt == 0)
	  return;

__hashtable& __h = _M_conjure_hashtable();
	__rehash_type& __rehash = __h._M_rehash_policy;
	const __rehash_state& __saved_state = __rehash._M_state();
	pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
							__h._M_element_count,
							__n_elt);

if (__do_rehash.first)
	  __h._M_rehash(__do_rehash.second, __saved_state);

for (; __first != __last; ++__first)
	  __h._M_insert(*__first, __node_gen, __unique_keys());
      }

/**
   *  Primary class template _Insert.
   *
   *  Defines @c insert member functions that depend on _Hashtable policies,
   *  via partial specializations.
   */
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits,
	   bool _Constant_iterators = _Traits::__constant_iterators::value>
    struct _Insert;

/// Specialization.
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
		   _RehashPolicy, _Traits, true>
    : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
			   _H1, _H2, _Hash, _RehashPolicy, _Traits>
    {
      using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
					_Equal, _H1, _H2, _Hash,
					_RehashPolicy, _Traits>;

using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
					       _Equal, _H1, _H2, _Hash,
					       _Traits>;

using value_type = typename __base_type::value_type;
      using iterator = typename __base_type::iterator;
      using const_iterator =  typename __base_type::const_iterator;

using __unique_keys = typename __base_type::__unique_keys;
      using __ireturn_type = typename __hashtable_base::__ireturn_type;
      using __hashtable = typename __base_type::__hashtable;
      using __node_gen_type = typename __base_type::__node_gen_type;

using __base_type::insert;

__ireturn_type
      insert(value_type&& __v)
      {
	__hashtable& __h = this->_M_conjure_hashtable();
	__node_gen_type __node_gen(__h);
	return __h._M_insert(std::move(__v), __node_gen, __unique_keys());
      }

iterator
      insert(const_iterator __hint, value_type&& __v)
      {
	__hashtable& __h = this->_M_conjure_hashtable();
	__node_gen_type __node_gen(__h);
	return __h._M_insert(__hint, std::move(__v), __node_gen,
			     __unique_keys());
      }
    };

/// Specialization.
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
		   _RehashPolicy, _Traits, false>
    : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
			   _H1, _H2, _Hash, _RehashPolicy, _Traits>
    {
      using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
				       _Equal, _H1, _H2, _Hash,
				       _RehashPolicy, _Traits>;
      using value_type = typename __base_type::value_type;
      using iterator = typename __base_type::iterator;
      using const_iterator =  typename __base_type::const_iterator;

using __unique_keys = typename __base_type::__unique_keys;
      using __hashtable = typename __base_type::__hashtable;
      using __ireturn_type = typename __base_type::__ireturn_type;

using __base_type::insert;

template<typename _Pair>
	using __is_cons = std::is_constructible<value_type, _Pair&&>;

template<typename _Pair>
	using _IFcons = std::enable_if<__is_cons<_Pair>::value>;

template<typename _Pair>
	using _IFconsp = typename _IFcons<_Pair>::type;

template<typename _Pair, typename = _IFconsp<_Pair>>
	__ireturn_type
	insert(_Pair&& __v)
	{
	  __hashtable& __h = this->_M_conjure_hashtable();
	  return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
	}

template<typename _Pair, typename = _IFconsp<_Pair>>
	iterator
	insert(const_iterator __hint, _Pair&& __v)
	{
	  __hashtable& __h = this->_M_conjure_hashtable();
	  return __h._M_emplace(__hint, __unique_keys(),
				std::forward<_Pair>(__v));
	}
   };

template<typename _Policy>
    using __has_load_factor = typename _Policy::__has_load_factor;

/**
   *  Primary class template  _Rehash_base.
   *
   *  Give hashtable the max_load_factor functions and reserve iff the
   *  rehash policy supports it.
  */
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits,
	   typename =
	     __detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>>
    struct _Rehash_base;

/// Specialization when rehash policy doesn't provide load factor management.
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits,
		      std::false_type>
    {
    };

/// Specialization when rehash policy provide load factor management.
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
			_H1, _H2, _Hash, _RehashPolicy, _Traits,
			std::true_type>
    {
      using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
				     _Equal, _H1, _H2, _Hash,
				     _RehashPolicy, _Traits>;

float
      max_load_factor() const noexcept
      {
	const __hashtable* __this = static_cast<const __hashtable*>(this);
	return __this->__rehash_policy().max_load_factor();
      }

void
      max_load_factor(float __z)
      {
	__hashtable* __this = static_cast<__hashtable*>(this);
	__this->__rehash_policy(_RehashPolicy(__z));
      }

void
      reserve(std::size_t __n)
      {
	__hashtable* __this = static_cast<__hashtable*>(this);
	__this->rehash(__builtin_ceil(__n / max_load_factor()));
      }
    };

/**
   *  Primary class template _Hashtable_ebo_helper.
   *
   *  Helper class using EBO when it is not forbidden (the type is not
   *  final) and when it is worth it (the type is empty.)
   */
  template<int _Nm, typename _Tp,
	   bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
    struct _Hashtable_ebo_helper;

/// Specialization using EBO.
  template<int _Nm, typename _Tp>
    struct _Hashtable_ebo_helper<_Nm, _Tp, true>
    : private _Tp
    {
      _Hashtable_ebo_helper() = default;

template<typename _OtherTp>
	_Hashtable_ebo_helper(_OtherTp&& __tp)
	  : _Tp(std::forward<_OtherTp>(__tp))
	{ }

static const _Tp&
      _S_cget(const _Hashtable_ebo_helper& __eboh)
      { return static_cast<const _Tp&>(__eboh); }

static _Tp&
      _S_get(_Hashtable_ebo_helper& __eboh)
      { return static_cast<_Tp&>(__eboh); }
    };

/// Specialization not using EBO.
  template<int _Nm, typename _Tp>
    struct _Hashtable_ebo_helper<_Nm, _Tp, false>
    {
      _Hashtable_ebo_helper() = default;

template<typename _OtherTp>
	_Hashtable_ebo_helper(_OtherTp&& __tp)
	  : _M_tp(std::forward<_OtherTp>(__tp))
	{ }

static const _Tp&
      _S_cget(const _Hashtable_ebo_helper& __eboh)
      { return __eboh._M_tp; }

static _Tp&
      _S_get(_Hashtable_ebo_helper& __eboh)
      { return __eboh._M_tp; }

private:
      _Tp _M_tp;
    };

/**
   *  Primary class template _Local_iterator_base.
   *
   *  Base class for local iterators, used to iterate within a bucket
   *  but not between buckets.
   */
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash,
	   bool __cache_hash_code>
    struct _Local_iterator_base;

/**
   *  Primary class template _Hash_code_base.
   *
   *  Encapsulates two policy issues that aren't quite orthogonal.
   *   (1) the difference between using a ranged hash function and using
   *       the combination of a hash function and a range-hashing function.
   *       In the former case we don't have such things as hash codes, so
   *       we have a dummy type as placeholder.
   *   (2) Whether or not we cache hash codes.  Caching hash codes is
   *       meaningless if we have a ranged hash function.
   *
   *  We also put the key extraction objects here, for convenience.
   *  Each specialization derives from one or more of the template
   *  parameters to benefit from Ebo. This is important as this type
   *  is inherited in some cases by the _Local_iterator_base type used
   *  to implement local_iterator and const_local_iterator. As with
   *  any iterator type we prefer to make it as small as possible.
   *
   *  Primary template is unused except as a hook for specializations.
   */
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash,
	   bool __cache_hash_code>
    struct _Hash_code_base;

/// Specialization: ranged hash function, no caching hash codes.  H1
  /// and H2 are provided but ignored.  We define a dummy hash code type.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash>
    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
    : private _Hashtable_ebo_helper<0, _ExtractKey>,
      private _Hashtable_ebo_helper<1, _Hash>
    {
    private:
      using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
      using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;

protected:
      typedef void* 					__hash_code;
      typedef _Hash_node<_Value, false>			__node_type;

// We need the default constructor for the local iterators and _Hashtable
      // default constructor.
      _Hash_code_base() = default;

_Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
		      const _Hash& __h)
      : __ebo_extract_key(__ex), __ebo_hash(__h) { }

__hash_code
      _M_hash_code(const _Key& __key) const
      { return 0; }

std::size_t
      _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
      { return _M_ranged_hash()(__k, __n); }

std::size_t
      _M_bucket_index(const __node_type* __p, std::size_t __n) const
	noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(),
						   (std::size_t)0)) )
      { return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); }

void
      _M_store_code(__node_type*, __hash_code) const
      { }

void
      _M_copy_code(__node_type*, const __node_type*) const
      { }

void
      _M_swap(_Hash_code_base& __x)
      {
	std::swap(_M_extract(), __x._M_extract());
	std::swap(_M_ranged_hash(), __x._M_ranged_hash());
      }

const _ExtractKey&
      _M_extract() const { return __ebo_extract_key::_S_cget(*this); }

_ExtractKey&
      _M_extract() { return __ebo_extract_key::_S_get(*this); }

const _Hash&
      _M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }

_Hash&
      _M_ranged_hash() { return __ebo_hash::_S_get(*this); }
    };

// No specialization for ranged hash function while caching hash codes.
  // That combination is meaningless, and trying to do it is an error.

/// Specialization: ranged hash function, cache hash codes.  This
  /// combination is meaningless, so we provide only a declaration
  /// and no definition.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash>
    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;

/// Specialization: hash function and range-hashing function, no
  /// caching of hash codes.
  /// Provides typedef and accessor required by C++ 11.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2>
    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
			   _Default_ranged_hash, false>
    : private _Hashtable_ebo_helper<0, _ExtractKey>,
      private _Hashtable_ebo_helper<1, _H1>,
      private _Hashtable_ebo_helper<2, _H2>
    {
    private:
      using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
      using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
      using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;

// Gives the local iterator implementation access to _M_bucket_index().
      friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
					 _Default_ranged_hash, false>;

public:
      typedef _H1 					hasher;

hasher
      hash_function() const
      { return _M_h1(); }

protected:
      typedef std::size_t 				__hash_code;
      typedef _Hash_node<_Value, false>			__node_type;

// We need the default constructor for the local iterators and _Hashtable
      // default constructor.
      _Hash_code_base() = default;

_Hash_code_base(const _ExtractKey& __ex,
		      const _H1& __h1, const _H2& __h2,
		      const _Default_ranged_hash&)
      : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }

__hash_code
      _M_hash_code(const _Key& __k) const
      {
	static_assert(__is_invocable<const _H1&, const _Key&>{},
	    "hash function must be invocable with an argument of key type");
	return _M_h1()(__k);
      }

std::size_t
      _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
      { return _M_h2()(__c, __n); }

std::size_t
      _M_bucket_index(const __node_type* __p, std::size_t __n) const
	noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>()))
		  && noexcept(declval<const _H2&>()((__hash_code)0,
						    (std::size_t)0)) )
      { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); }

void
      _M_store_code(__node_type*, __hash_code) const
      { }

void
      _M_copy_code(__node_type*, const __node_type*) const
      { }

void
      _M_swap(_Hash_code_base& __x)
      {
	std::swap(_M_extract(), __x._M_extract());
	std::swap(_M_h1(), __x._M_h1());
	std::swap(_M_h2(), __x._M_h2());
      }

const _ExtractKey&
      _M_extract() const { return __ebo_extract_key::_S_cget(*this); }

_ExtractKey&
      _M_extract() { return __ebo_extract_key::_S_get(*this); }

const _H1&
      _M_h1() const { return __ebo_h1::_S_cget(*this); }

_H1&
      _M_h1() { return __ebo_h1::_S_get(*this); }

const _H2&
      _M_h2() const { return __ebo_h2::_S_cget(*this); }

_H2&
      _M_h2() { return __ebo_h2::_S_get(*this); }
    };

/// Specialization: hash function and range-hashing function,
  /// caching hash codes.  H is provided but ignored.  Provides
  /// typedef and accessor required by C++ 11.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2>
    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
			   _Default_ranged_hash, true>
    : private _Hashtable_ebo_helper<0, _ExtractKey>,
      private _Hashtable_ebo_helper<1, _H1>,
      private _Hashtable_ebo_helper<2, _H2>
    {
    private:
      // Gives the local iterator implementation access to _M_h2().
      friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
					 _Default_ranged_hash, true>;

using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
      using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
      using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;

public:
      typedef _H1 					hasher;

hasher
      hash_function() const
      { return _M_h1(); }

protected:
      typedef std::size_t 				__hash_code;
      typedef _Hash_node<_Value, true>			__node_type;

// We need the default constructor for _Hashtable default constructor.
      _Hash_code_base() = default;
      _Hash_code_base(const _ExtractKey& __ex,
		      const _H1& __h1, const _H2& __h2,
		      const _Default_ranged_hash&)
      : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }

std::size_t
      _M_bucket_index(const _Key&, __hash_code __c,
		      std::size_t __n) const
      { return _M_h2()(__c, __n); }

std::size_t
      _M_bucket_index(const __node_type* __p, std::size_t __n) const
	noexcept( noexcept(declval<const _H2&>()((__hash_code)0,
						 (std::size_t)0)) )
      { return _M_h2()(__p->_M_hash_code, __n); }

void
      _M_store_code(__node_type* __n, __hash_code __c) const
      { __n->_M_hash_code = __c; }

void
      _M_copy_code(__node_type* __to, const __node_type* __from) const
      { __to->_M_hash_code = __from->_M_hash_code; }

void
      _M_swap(_Hash_code_base& __x)
      {
	std::swap(_M_extract(), __x._M_extract());
	std::swap(_M_h1(), __x._M_h1());
	std::swap(_M_h2(), __x._M_h2());
      }

const _ExtractKey&
      _M_extract() const { return __ebo_extract_key::_S_cget(*this); }

_ExtractKey&
      _M_extract() { return __ebo_extract_key::_S_get(*this); }

const _H1&
      _M_h1() const { return __ebo_h1::_S_cget(*this); }

_H1&
      _M_h1() { return __ebo_h1::_S_get(*this); }

const _H2&
      _M_h2() const { return __ebo_h2::_S_cget(*this); }

_H2&
      _M_h2() { return __ebo_h2::_S_get(*this); }
    };

/**
   *  Primary class template _Equal_helper.
   *
   */
  template <typename _Key, typename _Value, typename _ExtractKey,
	    typename _Equal, typename _HashCodeType,
	    bool __cache_hash_code>
  struct _Equal_helper;

/// Specialization.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _Equal, typename _HashCodeType>
  struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
  {
    static bool
    _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
	      const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
    { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); }
  };

/// Specialization.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _Equal, typename _HashCodeType>
  struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
  {
    static bool
    _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
	      const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
    { return __eq(__k, __extract(__n->_M_v())); }
  };

/// Partial specialization used when nodes contain a cached hash code.
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash>
    struct _Local_iterator_base<_Key, _Value, _ExtractKey,
				_H1, _H2, _Hash, true>
    : private _Hashtable_ebo_helper<0, _H2>
    {
    protected:
      using __base_type = _Hashtable_ebo_helper<0, _H2>;
      using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
					       _H1, _H2, _Hash, true>;

_Local_iterator_base() = default;
      _Local_iterator_base(const __hash_code_base& __base,
			   _Hash_node<_Value, true>* __p,
			   std::size_t __bkt, std::size_t __bkt_count)
      : __base_type(__base._M_h2()),
	_M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }

void
      _M_incr()
      {
	_M_cur = _M_cur->_M_next();
	if (_M_cur)
	  {
	    std::size_t __bkt
	      = __base_type::_S_get(*this)(_M_cur->_M_hash_code,
					   _M_bucket_count);
	    if (__bkt != _M_bucket)
	      _M_cur = nullptr;
	  }
      }

_Hash_node<_Value, true>*  _M_cur;
      std::size_t _M_bucket;
      std::size_t _M_bucket_count;

public:
      const void*
      _M_curr() const { return _M_cur; }  // for equality ops

std::size_t
      _M_get_bucket() const { return _M_bucket; }  // for debug mode
    };

// Uninitialized storage for a _Hash_code_base.
  // This type is DefaultConstructible and Assignable even if the
  // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
  // can be DefaultConstructible and Assignable.
  template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
    struct _Hash_code_storage
    {
      __gnu_cxx::__aligned_buffer<_Tp> _M_storage;

_Tp*
      _M_h() { return _M_storage._M_ptr(); }

const _Tp*
      _M_h() const { return _M_storage._M_ptr(); }
    };

// Empty partial specialization for empty _Hash_code_base types.
  template<typename _Tp>
    struct _Hash_code_storage<_Tp, true>
    {
      static_assert( std::is_empty<_Tp>::value, "Type must be empty" );

// As _Tp is an empty type there will be no bytes written/read through
      // the cast pointer, so no strict-aliasing violation.
      _Tp*
      _M_h() { return reinterpret_cast<_Tp*>(this); }

const _Tp*
      _M_h() const { return reinterpret_cast<const _Tp*>(this); }
    };

template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash>
    using __hash_code_for_local_iter
      = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
					   _H1, _H2, _Hash, false>>;

// Partial specialization used when hash codes are not cached
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash>
    struct _Local_iterator_base<_Key, _Value, _ExtractKey,
				_H1, _H2, _Hash, false>
    : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash>
    {
    protected:
      using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
					       _H1, _H2, _Hash, false>;

_Local_iterator_base() : _M_bucket_count(-1) { }

_Local_iterator_base(const __hash_code_base& __base,
			   _Hash_node<_Value, false>* __p,
			   std::size_t __bkt, std::size_t __bkt_count)
      : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
      { _M_init(__base); }

~_Local_iterator_base()
      {
	if (_M_bucket_count != -1)
	  _M_destroy();
      }

_Local_iterator_base(const _Local_iterator_base& __iter)
      : _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket),
        _M_bucket_count(__iter._M_bucket_count)
      {
	if (_M_bucket_count != -1)
	  _M_init(*__iter._M_h());
      }

_Local_iterator_base&
      operator=(const _Local_iterator_base& __iter)
      {
	if (_M_bucket_count != -1)
	  _M_destroy();
	_M_cur = __iter._M_cur;
	_M_bucket = __iter._M_bucket;
	_M_bucket_count = __iter._M_bucket_count;
	if (_M_bucket_count != -1)
	  _M_init(*__iter._M_h());
	return *this;
      }

void
      _M_incr()
      {
	_M_cur = _M_cur->_M_next();
	if (_M_cur)
	  {
	    std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur,
							      _M_bucket_count);
	    if (__bkt != _M_bucket)
	      _M_cur = nullptr;
	  }
      }

_Hash_node<_Value, false>*  _M_cur;
      std::size_t _M_bucket;
      std::size_t _M_bucket_count;

void
      _M_init(const __hash_code_base& __base)
      { ::new(this->_M_h()) __hash_code_base(__base); }

void
      _M_destroy() { this->_M_h()->~__hash_code_base(); }

public:
      const void*
      _M_curr() const { return _M_cur; }  // for equality ops and debug mode

std::size_t
      _M_get_bucket() const { return _M_bucket; }  // for debug mode
    };

template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash, bool __cache>
    inline bool
    operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
					  _H1, _H2, _Hash, __cache>& __x,
	       const _Local_iterator_base<_Key, _Value, _ExtractKey,
					  _H1, _H2, _Hash, __cache>& __y)
    { return __x._M_curr() == __y._M_curr(); }

template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash, bool __cache>
    inline bool
    operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
					  _H1, _H2, _Hash, __cache>& __x,
	       const _Local_iterator_base<_Key, _Value, _ExtractKey,
					  _H1, _H2, _Hash, __cache>& __y)
    { return __x._M_curr() != __y._M_curr(); }

/// local iterators
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash,
	   bool __constant_iterators, bool __cache>
    struct _Local_iterator
    : public _Local_iterator_base<_Key, _Value, _ExtractKey,
				  _H1, _H2, _Hash, __cache>
    {
    private:
      using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
					       _H1, _H2, _Hash, __cache>;
      using __hash_code_base = typename __base_type::__hash_code_base;
    public:
      typedef _Value					value_type;
      typedef typename std::conditional<__constant_iterators,
					const _Value*, _Value*>::type
						       pointer;
      typedef typename std::conditional<__constant_iterators,
					const _Value&, _Value&>::type
						       reference;
      typedef std::ptrdiff_t				difference_type;
      typedef std::forward_iterator_tag			iterator_category;

_Local_iterator() = default;

_Local_iterator(const __hash_code_base& __base,
		      _Hash_node<_Value, __cache>* __p,
		      std::size_t __bkt, std::size_t __bkt_count)
	: __base_type(__base, __p, __bkt, __bkt_count)
      { }

reference
      operator*() const
      { return this->_M_cur->_M_v(); }

pointer
      operator->() const
      { return this->_M_cur->_M_valptr(); }

_Local_iterator&
      operator++()
      {
	this->_M_incr();
	return *this;
      }

_Local_iterator
      operator++(int)
      {
	_Local_iterator __tmp(*this);
	this->_M_incr();
	return __tmp;
      }
    };

/// local const_iterators
  template<typename _Key, typename _Value, typename _ExtractKey,
	   typename _H1, typename _H2, typename _Hash,
	   bool __constant_iterators, bool __cache>
    struct _Local_const_iterator
    : public _Local_iterator_base<_Key, _Value, _ExtractKey,
				  _H1, _H2, _Hash, __cache>
    {
    private:
      using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
					       _H1, _H2, _Hash, __cache>;
      using __hash_code_base = typename __base_type::__hash_code_base;

public:
      typedef _Value					value_type;
      typedef const _Value*				pointer;
      typedef const _Value&				reference;
      typedef std::ptrdiff_t				difference_type;
      typedef std::forward_iterator_tag			iterator_category;

_Local_const_iterator() = default;

_Local_const_iterator(const __hash_code_base& __base,
			    _Hash_node<_Value, __cache>* __p,
			    std::size_t __bkt, std::size_t __bkt_count)
	: __base_type(__base, __p, __bkt, __bkt_count)
      { }

_Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
						  _H1, _H2, _Hash,
						  __constant_iterators,
						  __cache>& __x)
	: __base_type(__x)
      { }

reference
      operator*() const
      { return this->_M_cur->_M_v(); }

pointer
      operator->() const
      { return this->_M_cur->_M_valptr(); }

_Local_const_iterator&
      operator++()
      {
	this->_M_incr();
	return *this;
      }

_Local_const_iterator
      operator++(int)
      {
	_Local_const_iterator __tmp(*this);
	this->_M_incr();
	return __tmp;
      }
    };

/**
   *  Primary class template _Hashtable_base.
   *
   *  Helper class adding management of _Equal functor to
   *  _Hash_code_base type.
   *
   *  Base class templates are:
   *    - __detail::_Hash_code_base
   *    - __detail::_Hashtable_ebo_helper
   */
  template<typename _Key, typename _Value,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash, typename _Traits>
  struct _Hashtable_base
  : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
			   _Traits::__hash_cached::value>,
    private _Hashtable_ebo_helper<0, _Equal>
  {
  public:
    typedef _Key					key_type;
    typedef _Value					value_type;
    typedef _Equal					key_equal;
    typedef std::size_t					size_type;
    typedef std::ptrdiff_t				difference_type;

using __traits_type = _Traits;
    using __hash_cached = typename __traits_type::__hash_cached;
    using __constant_iterators = typename __traits_type::__constant_iterators;
    using __unique_keys = typename __traits_type::__unique_keys;

using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
					     _H1, _H2, _Hash,
					     __hash_cached::value>;

using __hash_code = typename __hash_code_base::__hash_code;
    using __node_type = typename __hash_code_base::__node_type;

using iterator = __detail::_Node_iterator<value_type,
					      __constant_iterators::value,
					      __hash_cached::value>;

using const_iterator = __detail::_Node_const_iterator<value_type,
						   __constant_iterators::value,
						   __hash_cached::value>;

using local_iterator = __detail::_Local_iterator<key_type, value_type,
						  _ExtractKey, _H1, _H2, _Hash,
						  __constant_iterators::value,
						     __hash_cached::value>;

using const_local_iterator = __detail::_Local_const_iterator<key_type,
								 value_type,
					_ExtractKey, _H1, _H2, _Hash,
					__constant_iterators::value,
					__hash_cached::value>;

using __ireturn_type = typename std::conditional<__unique_keys::value,
						     std::pair<iterator, bool>,
						     iterator>::type;
  private:
    using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
    using _EqualHelper =  _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
					__hash_code, __hash_cached::value>;

protected:
    _Hashtable_base() = default;
    _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
		    const _Hash& __hash, const _Equal& __eq)
    : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
    { }

bool
    _M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
    {
      static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
	  "key equality predicate must be invocable with two arguments of "
	  "key type");
      return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
				     __k, __c, __n);
    }

void
    _M_swap(_Hashtable_base& __x)
    {
      __hash_code_base::_M_swap(__x);
      std::swap(_M_eq(), __x._M_eq());
    }

const _Equal&
    _M_eq() const { return _EqualEBO::_S_cget(*this); }

_Equal&
    _M_eq() { return _EqualEBO::_S_get(*this); }
  };

/**
   *  struct _Equality_base.
   *
   *  Common types and functions for class _Equality.
   */
  struct _Equality_base
  {
  protected:
    template<typename _Uiterator>
      static bool
      _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
  };

// See std::is_permutation in N3068.
  template<typename _Uiterator>
    bool
    _Equality_base::
    _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
		      _Uiterator __first2)
    {
      for (; __first1 != __last1; ++__first1, ++__first2)
	if (!(*__first1 == *__first2))
	  break;

if (__first1 == __last1)
	return true;

_Uiterator __last2 = __first2;
      std::advance(__last2, std::distance(__first1, __last1));

for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
	{
	  _Uiterator __tmp =  __first1;
	  while (__tmp != __it1 && !bool(*__tmp == *__it1))
	    ++__tmp;

// We've seen this one before.
	  if (__tmp != __it1)
	    continue;

std::ptrdiff_t __n2 = 0;
	  for (__tmp = __first2; __tmp != __last2; ++__tmp)
	    if (*__tmp == *__it1)
	      ++__n2;

if (!__n2)
	    return false;

std::ptrdiff_t __n1 = 0;
	  for (__tmp = __it1; __tmp != __last1; ++__tmp)
	    if (*__tmp == *__it1)
	      ++__n1;

if (__n1 != __n2)
	    return false;
	}
      return true;
    }

/**
   *  Primary class template  _Equality.
   *
   *  This is for implementing equality comparison for unordered
   *  containers, per N3068, by John Lakos and Pablo Halpern.
   *  Algorithmically, we follow closely the reference implementations
   *  therein.
   */
  template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits,
	   bool _Unique_keys = _Traits::__unique_keys::value>
    struct _Equality;

bool
      _M_equal(const __hashtable&) const;
    };

template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    bool
    _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    _M_equal(const __hashtable& __other) const
    {
      const __hashtable* __this = static_cast<const __hashtable*>(this);

if (__this->size() != __other.size())
	return false;

for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
	{
	  const auto __ity = __other.find(_ExtractKey()(*__itx));
	  if (__ity == __other.end() || !bool(*__ity == *__itx))
	    return false;
	}
      return true;
    }

bool
      _M_equal(const __hashtable&) const;
    };

template<typename _Key, typename _Value, typename _Alloc,
	   typename _ExtractKey, typename _Equal,
	   typename _H1, typename _H2, typename _Hash,
	   typename _RehashPolicy, typename _Traits>
    bool
    _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
	      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
    _M_equal(const __hashtable& __other) const
    {
      const __hashtable* __this = static_cast<const __hashtable*>(this);

if (__this->size() != __other.size())
	return false;

for (auto __itx = __this->begin(); __itx != __this->end();)
	{
	  const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
	  const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));

if (std::distance(__xrange.first, __xrange.second)
	      != std::distance(__yrange.first, __yrange.second))
	    return false;

if (!_S_is_permutation(__xrange.first, __xrange.second,
				 __yrange.first))
	    return false;

__itx = __xrange.second;
	}
      return true;
    }

/**
   * This type deals with all allocation and keeps an allocator instance through
   * inheritance to benefit from EBO when possible.
   */
  template<typename _NodeAlloc>
    struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
    {
    private:
      using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
    public:
      using __node_type = typename _NodeAlloc::value_type;
      using __node_alloc_type = _NodeAlloc;
      // Use __gnu_cxx to benefit from _S_always_equal and al.
      using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;

using __value_alloc_traits = typename __node_alloc_traits::template
	rebind_traits<typename __node_type::value_type>;

using __node_base = __detail::_Hash_node_base;
      using __bucket_type = __node_base*;      
      using __bucket_alloc_type =
	__alloc_rebind<__node_alloc_type, __bucket_type>;
      using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>;

_Hashtable_alloc() = default;
      _Hashtable_alloc(const _Hashtable_alloc&) = default;
      _Hashtable_alloc(_Hashtable_alloc&&) = default;

template<typename _Alloc>
	_Hashtable_alloc(_Alloc&& __a)
	  : __ebo_node_alloc(std::forward<_Alloc>(__a))
	{ }

__node_alloc_type&
      _M_node_allocator()
      { return __ebo_node_alloc::_S_get(*this); }

const __node_alloc_type&
      _M_node_allocator() const
      { return __ebo_node_alloc::_S_cget(*this); }

template<typename... _Args>
	__node_type*
	_M_allocate_node(_Args&&... __args);

void
      _M_deallocate_node(__node_type* __n);

// Deallocate the linked list of nodes pointed to by __n
      void
      _M_deallocate_nodes(__node_type* __n);

__bucket_type*
      _M_allocate_buckets(std::size_t __n);

void
      _M_deallocate_buckets(__bucket_type*, std::size_t __n);
    };

// Definitions of class template _Hashtable_alloc's out-of-line member
  // functions.
  template<typename _NodeAlloc>
    template<typename... _Args>
      typename _Hashtable_alloc<_NodeAlloc>::__node_type*
      _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
      {
	auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
	__node_type* __n = std::__to_address(__nptr);
	__try
	  {
	    ::new ((void*)__n) __node_type;
	    __node_alloc_traits::construct(_M_node_allocator(),
					   __n->_M_valptr(),
					   std::forward<_Args>(__args)...);
	    return __n;
	  }
	__catch(...)
	  {
	    __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
	    __throw_exception_again;
	  }
      }

template<typename _NodeAlloc>
    void
    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
    {
      typedef typename __node_alloc_traits::pointer _Ptr;
      auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
      __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
      __n->~__node_type();
      __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
    }

template<typename _NodeAlloc>
    void
    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type* __n)
    {
      while (__n)
	{
	  __node_type* __tmp = __n;
	  __n = __n->_M_next();
	  _M_deallocate_node(__tmp);
	}
    }

template<typename _NodeAlloc>
    typename _Hashtable_alloc<_NodeAlloc>::__bucket_type*
    _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n)
    {
      __bucket_alloc_type __alloc(_M_node_allocator());

auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
      __bucket_type* __p = std::__to_address(__ptr);
      __builtin_memset(__p, 0, __n * sizeof(__bucket_type));
      return __p;
    }

template<typename _NodeAlloc>
    void
    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts,
							std::size_t __n)
    {
      typedef typename __bucket_alloc_traits::pointer _Ptr;
      auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
      __bucket_alloc_type __alloc(_M_node_allocator());
      __bucket_alloc_traits::deallocate(__alloc, __ptr, __n);
    }

//@} hashtable-detail
} // namespace __detail
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // _HASHTABLE_POLICY_H

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