LCOV - code coverage report
Current view: top level - usr/include/c++/7/bits - hashtable_policy.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 129 140 92.1 %
Date: 2020-10-15 20:26:03 Functions: 94 97 96.9 %

          Line data    Source code
       1             : // Internal policy header for unordered_set and unordered_map -*- C++ -*-
       2             : 
       3             : // Copyright (C) 2010-2017 Free Software Foundation, Inc.
       4             : //
       5             : // This file is part of the GNU ISO C++ Library.  This library is free
       6             : // software; you can redistribute it and/or modify it under the
       7             : // terms of the GNU General Public License as published by the
       8             : // Free Software Foundation; either version 3, or (at your option)
       9             : // any later version.
      10             : 
      11             : // This library is distributed in the hope that it will be useful,
      12             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             : // GNU General Public License for more details.
      15             : 
      16             : // Under Section 7 of GPL version 3, you are granted additional
      17             : // permissions described in the GCC Runtime Library Exception, version
      18             : // 3.1, as published by the Free Software Foundation.
      19             : 
      20             : // You should have received a copy of the GNU General Public License and
      21             : // a copy of the GCC Runtime Library Exception along with this program;
      22             : // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      23             : // <http://www.gnu.org/licenses/>.
      24             : 
      25             : /** @file bits/hashtable_policy.h
      26             :  *  This is an internal header file, included by other library headers.
      27             :  *  Do not attempt to use it directly.
      28             :  *  @headername{unordered_map,unordered_set}
      29             :  */
      30             : 
      31             : #ifndef _HASHTABLE_POLICY_H
      32             : #define _HASHTABLE_POLICY_H 1
      33             : 
      34             : #include <bits/stl_algobase.h> // for std::min.
      35             : 
      36             : namespace std _GLIBCXX_VISIBILITY(default)
      37             : {
      38             : _GLIBCXX_BEGIN_NAMESPACE_VERSION
      39             : 
      40             :   template<typename _Key, typename _Value, typename _Alloc,
      41             :            typename _ExtractKey, typename _Equal,
      42             :            typename _H1, typename _H2, typename _Hash,
      43             :            typename _RehashPolicy, typename _Traits>
      44             :     class _Hashtable;
      45             : 
      46             : _GLIBCXX_END_NAMESPACE_VERSION
      47             : 
      48             : namespace __detail
      49             : {
      50             : _GLIBCXX_BEGIN_NAMESPACE_VERSION
      51             : 
      52             :   /**
      53             :    *  @defgroup hashtable-detail Base and Implementation Classes
      54             :    *  @ingroup unordered_associative_containers
      55             :    *  @{
      56             :    */
      57             :   template<typename _Key, typename _Value,
      58             :            typename _ExtractKey, typename _Equal,
      59             :            typename _H1, typename _H2, typename _Hash, typename _Traits>
      60             :     struct _Hashtable_base;
      61             : 
      62             :   // Helper function: return distance(first, last) for forward
      63             :   // iterators, or 0 for input iterators.
      64             :   template<class _Iterator>
      65             :     inline typename std::iterator_traits<_Iterator>::difference_type
      66             :     __distance_fw(_Iterator __first, _Iterator __last,
      67             :                   std::input_iterator_tag)
      68             :     { return 0; }
      69             : 
      70             :   template<class _Iterator>
      71             :     inline typename std::iterator_traits<_Iterator>::difference_type
      72           1 :     __distance_fw(_Iterator __first, _Iterator __last,
      73             :                   std::forward_iterator_tag)
      74           1 :     { return std::distance(__first, __last); }
      75             : 
      76             :   template<class _Iterator>
      77             :     inline typename std::iterator_traits<_Iterator>::difference_type
      78           1 :     __distance_fw(_Iterator __first, _Iterator __last)
      79             :     {
      80             :       typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag;
      81           1 :       return __distance_fw(__first, __last, _Tag());
      82             :     }
      83             : 
      84             :   // Helper type used to detect whether the hash functor is noexcept.
      85             :   template <typename _Key, typename _Hash>
      86             :     struct __is_noexcept_hash : std::__bool_constant<
      87             :         noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
      88             :     { };
      89             : 
      90             :   struct _Identity
      91             :   {
      92             :     template<typename _Tp>
      93             :       _Tp&&
      94             :       operator()(_Tp&& __x) const
      95             :       { return std::forward<_Tp>(__x); }
      96             :   };
      97             : 
      98             :   struct _Select1st
      99             :   {
     100             :     template<typename _Tp>
     101             :       auto
     102        3353 :       operator()(_Tp&& __x) const
     103             :       -> decltype(std::get<0>(std::forward<_Tp>(__x)))
     104        3353 :       { return std::get<0>(std::forward<_Tp>(__x)); }
     105             :   };
     106             : 
     107             :   template<typename _NodeAlloc>
     108             :     struct _Hashtable_alloc;
     109             : 
     110             :   // Functor recycling a pool of nodes and using allocation once the pool is
     111             :   // empty.
     112             :   template<typename _NodeAlloc>
     113             :     struct _ReuseOrAllocNode
     114             :     {
     115             :     private:
     116             :       using __node_alloc_type = _NodeAlloc;
     117             :       using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
     118             :       using __value_alloc_type = typename __hashtable_alloc::__value_alloc_type;
     119             :       using __value_alloc_traits =
     120             :         typename __hashtable_alloc::__value_alloc_traits;
     121             :       using __node_alloc_traits =
     122             :         typename __hashtable_alloc::__node_alloc_traits;
     123             :       using __node_type = typename __hashtable_alloc::__node_type;
     124             : 
     125             :     public:
     126             :       _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
     127             :         : _M_nodes(__nodes), _M_h(__h) { }
     128             :       _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
     129             : 
     130             :       ~_ReuseOrAllocNode()
     131             :       { _M_h._M_deallocate_nodes(_M_nodes); }
     132             : 
     133             :       template<typename _Arg>
     134             :         __node_type*
     135             :         operator()(_Arg&& __arg) const
     136             :         {
     137             :           if (_M_nodes)
     138             :             {
     139             :               __node_type* __node = _M_nodes;
     140             :               _M_nodes = _M_nodes->_M_next();
     141             :               __node->_M_nxt = nullptr;
     142             :               __value_alloc_type __a(_M_h._M_node_allocator());
     143             :               __value_alloc_traits::destroy(__a, __node->_M_valptr());
     144             :               __try
     145             :                 {
     146             :                   __value_alloc_traits::construct(__a, __node->_M_valptr(),
     147             :                                                   std::forward<_Arg>(__arg));
     148             :                 }
     149             :               __catch(...)
     150             :                 {
     151             :                   __node->~__node_type();
     152             :                   __node_alloc_traits::deallocate(_M_h._M_node_allocator(),
     153             :                                                   __node, 1);
     154             :                   __throw_exception_again;
     155             :                 }
     156             :               return __node;
     157             :             }
     158             :           return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
     159             :         }
     160             : 
     161             :     private:
     162             :       mutable __node_type* _M_nodes;
     163             :       __hashtable_alloc& _M_h;
     164             :     };
     165             : 
     166             :   // Functor similar to the previous one but without any pool of nodes to
     167             :   // recycle.
     168             :   template<typename _NodeAlloc>
     169             :     struct _AllocNode
     170             :     {
     171             :     private:
     172             :       using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
     173             :       using __node_type = typename __hashtable_alloc::__node_type;
     174             : 
     175             :     public:
     176           7 :       _AllocNode(__hashtable_alloc& __h)
     177           7 :         : _M_h(__h) { }
     178             : 
     179             :       template<typename _Arg>
     180             :         __node_type*
     181           7 :         operator()(_Arg&& __arg) const
     182           7 :         { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
     183             : 
     184             :     private:
     185             :       __hashtable_alloc& _M_h;
     186             :     };
     187             : 
     188             :   // Auxiliary types used for all instantiations of _Hashtable nodes
     189             :   // and iterators.
     190             : 
     191             :   /**
     192             :    *  struct _Hashtable_traits
     193             :    *
     194             :    *  Important traits for hash tables.
     195             :    *
     196             :    *  @tparam _Cache_hash_code  Boolean value. True if the value of
     197             :    *  the hash function is stored along with the value. This is a
     198             :    *  time-space tradeoff.  Storing it may improve lookup speed by
     199             :    *  reducing the number of times we need to call the _Equal
     200             :    *  function.
     201             :    *
     202             :    *  @tparam _Constant_iterators  Boolean value. True if iterator and
     203             :    *  const_iterator are both constant iterator types. This is true
     204             :    *  for unordered_set and unordered_multiset, false for
     205             :    *  unordered_map and unordered_multimap.
     206             :    *
     207             :    *  @tparam _Unique_keys  Boolean value. True if the return value
     208             :    *  of _Hashtable::count(k) is always at most one, false if it may
     209             :    *  be an arbitrary number. This is true for unordered_set and
     210             :    *  unordered_map, false for unordered_multiset and
     211             :    *  unordered_multimap.
     212             :    */
     213             :   template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
     214             :     struct _Hashtable_traits
     215             :     {
     216             :       using __hash_cached = __bool_constant<_Cache_hash_code>;
     217             :       using __constant_iterators = __bool_constant<_Constant_iterators>;
     218             :       using __unique_keys = __bool_constant<_Unique_keys>;
     219             :     };
     220             : 
     221             :   /**
     222             :    *  struct _Hash_node_base
     223             :    *
     224             :    *  Nodes, used to wrap elements stored in the hash table.  A policy
     225             :    *  template parameter of class template _Hashtable controls whether
     226             :    *  nodes also store a hash code. In some cases (e.g. strings) this
     227             :    *  may be a performance win.
     228             :    */
     229             :   struct _Hash_node_base
     230             :   {
     231             :     _Hash_node_base* _M_nxt;
     232             : 
     233        1222 :     _Hash_node_base() noexcept : _M_nxt() { }
     234             : 
     235             :     _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
     236             :   };
     237             : 
     238             :   /**
     239             :    *  struct _Hash_node_value_base
     240             :    *
     241             :    *  Node type with the value to store.
     242             :    */
     243             :   template<typename _Value>
     244        1201 :     struct _Hash_node_value_base : _Hash_node_base
     245             :     {
     246             :       typedef _Value value_type;
     247             : 
     248             :       __gnu_cxx::__aligned_buffer<_Value> _M_storage;
     249             : 
     250             :       _Value*
     251        4217 :       _M_valptr() noexcept
     252        4217 :       { return _M_storage._M_ptr(); }
     253             : 
     254             :       const _Value*
     255        2935 :       _M_valptr() const noexcept
     256        2935 :       { return _M_storage._M_ptr(); }
     257             : 
     258             :       _Value&
     259         611 :       _M_v() noexcept
     260         611 :       { return *_M_valptr(); }
     261             : 
     262             :       const _Value&
     263        2935 :       _M_v() const noexcept
     264        2935 :       { return *_M_valptr(); }
     265             :     };
     266             : 
     267             :   /**
     268             :    *  Primary template struct _Hash_node.
     269             :    */
     270             :   template<typename _Value, bool _Cache_hash_code>
     271             :     struct _Hash_node;
     272             : 
     273             :   /**
     274             :    *  Specialization for nodes with caches, struct _Hash_node.
     275             :    *
     276             :    *  Base class is __detail::_Hash_node_value_base.
     277             :    */
     278             :   template<typename _Value>
     279             :     struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value>
     280             :     {
     281             :       std::size_t  _M_hash_code;
     282             : 
     283             :       _Hash_node*
     284             :       _M_next() const noexcept
     285             :       { return static_cast<_Hash_node*>(this->_M_nxt); }
     286             :     };
     287             : 
     288             :   /**
     289             :    *  Specialization for nodes without caches, struct _Hash_node.
     290             :    *
     291             :    *  Base class is __detail::_Hash_node_value_base.
     292             :    */
     293             :   template<typename _Value>
     294        1201 :     struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value>
     295             :     {
     296             :       _Hash_node*
     297        4136 :       _M_next() const noexcept
     298        4136 :       { return static_cast<_Hash_node*>(this->_M_nxt); }
     299             :     };
     300             : 
     301             :   /// Base class for node iterators.
     302             :   template<typename _Value, bool _Cache_hash_code>
     303             :     struct _Node_iterator_base
     304             :     {
     305             :       using __node_type = _Hash_node<_Value, _Cache_hash_code>;
     306             : 
     307             :       __node_type*  _M_cur;
     308             : 
     309        1221 :       _Node_iterator_base(__node_type* __p) noexcept
     310        1221 :       : _M_cur(__p) { }
     311             : 
     312             :       void
     313             :       _M_incr() noexcept
     314             :       { _M_cur = _M_cur->_M_next(); }
     315             :     };
     316             : 
     317             :   template<typename _Value, bool _Cache_hash_code>
     318             :     inline bool
     319          10 :     operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
     320             :                const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
     321             :     noexcept
     322          10 :     { return __x._M_cur == __y._M_cur; }
     323             : 
     324             :   template<typename _Value, bool _Cache_hash_code>
     325             :     inline bool
     326           0 :     operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
     327             :                const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
     328             :     noexcept
     329           0 :     { return __x._M_cur != __y._M_cur; }
     330             : 
     331             :   /// Node iterators, used to iterate through all the hashtable.
     332             :   template<typename _Value, bool __constant_iterators, bool __cache>
     333             :     struct _Node_iterator
     334             :     : public _Node_iterator_base<_Value, __cache>
     335             :     {
     336             :     private:
     337             :       using __base_type = _Node_iterator_base<_Value, __cache>;
     338             :       using __node_type = typename __base_type::__node_type;
     339             : 
     340             :     public:
     341             :       typedef _Value                                    value_type;
     342             :       typedef std::ptrdiff_t                            difference_type;
     343             :       typedef std::forward_iterator_tag                 iterator_category;
     344             : 
     345             :       using pointer = typename std::conditional<__constant_iterators,
     346             :                                                 const _Value*, _Value*>::type;
     347             : 
     348             :       using reference = typename std::conditional<__constant_iterators,
     349             :                                                   const _Value&, _Value&>::type;
     350             : 
     351             :       _Node_iterator() noexcept
     352             :       : __base_type(0) { }
     353             : 
     354             :       explicit
     355        1221 :       _Node_iterator(__node_type* __p) noexcept
     356        1221 :       : __base_type(__p) { }
     357             : 
     358             :       reference
     359             :       operator*() const noexcept
     360             :       { return this->_M_cur->_M_v(); }
     361             : 
     362             :       pointer
     363        1204 :       operator->() const noexcept
     364        1204 :       { return this->_M_cur->_M_valptr(); }
     365             : 
     366             :       _Node_iterator&
     367             :       operator++() noexcept
     368             :       {
     369             :         this->_M_incr();
     370             :         return *this;
     371             :       }
     372             : 
     373             :       _Node_iterator
     374             :       operator++(int) noexcept
     375             :       {
     376             :         _Node_iterator __tmp(*this);
     377             :         this->_M_incr();
     378             :         return __tmp;
     379             :       }
     380             :     };
     381             : 
     382             :   /// Node const_iterators, used to iterate through all the hashtable.
     383             :   template<typename _Value, bool __constant_iterators, bool __cache>
     384             :     struct _Node_const_iterator
     385             :     : public _Node_iterator_base<_Value, __cache>
     386             :     {
     387             :     private:
     388             :       using __base_type = _Node_iterator_base<_Value, __cache>;
     389             :       using __node_type = typename __base_type::__node_type;
     390             : 
     391             :     public:
     392             :       typedef _Value                                    value_type;
     393             :       typedef std::ptrdiff_t                            difference_type;
     394             :       typedef std::forward_iterator_tag                 iterator_category;
     395             : 
     396             :       typedef const _Value*                             pointer;
     397             :       typedef const _Value&                         reference;
     398             : 
     399             :       _Node_const_iterator() noexcept
     400             :       : __base_type(0) { }
     401             : 
     402             :       explicit
     403             :       _Node_const_iterator(__node_type* __p) noexcept
     404             :       : __base_type(__p) { }
     405             : 
     406           0 :       _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
     407             :                            __cache>& __x) noexcept
     408           0 :       : __base_type(__x._M_cur) { }
     409             : 
     410             :       reference
     411             :       operator*() const noexcept
     412             :       { return this->_M_cur->_M_v(); }
     413             : 
     414             :       pointer
     415             :       operator->() const noexcept
     416             :       { return this->_M_cur->_M_valptr(); }
     417             : 
     418             :       _Node_const_iterator&
     419             :       operator++() noexcept
     420             :       {
     421             :         this->_M_incr();
     422             :         return *this;
     423             :       }
     424             : 
     425             :       _Node_const_iterator
     426             :       operator++(int) noexcept
     427             :       {
     428             :         _Node_const_iterator __tmp(*this);
     429             :         this->_M_incr();
     430             :         return __tmp;
     431             :       }
     432             :     };
     433             : 
     434             :   // Many of class template _Hashtable's template parameters are policy
     435             :   // classes.  These are defaults for the policies.
     436             : 
     437             :   /// Default range hashing function: use division to fold a large number
     438             :   /// into the range [0, N).
     439             :   struct _Mod_range_hashing
     440             :   {
     441             :     typedef std::size_t first_argument_type;
     442             :     typedef std::size_t second_argument_type;
     443             :     typedef std::size_t result_type;
     444             : 
     445             :     result_type
     446        4633 :     operator()(first_argument_type __num,
     447             :                second_argument_type __den) const noexcept
     448        4633 :     { return __num % __den; }
     449             :   };
     450             : 
     451             :   /// Default ranged hash function H.  In principle it should be a
     452             :   /// function object composed from objects of type H1 and H2 such that
     453             :   /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
     454             :   /// h1 and h2.  So instead we'll just use a tag to tell class template
     455             :   /// hashtable to do that composition.
     456             :   struct _Default_ranged_hash { };
     457             : 
     458             :   /// Default value for rehash policy.  Bucket size is (usually) the
     459             :   /// smallest prime that keeps the load factor small enough.
     460             :   struct _Prime_rehash_policy
     461             :   {
     462             :     using __has_load_factor = std::true_type;
     463             : 
     464          21 :     _Prime_rehash_policy(float __z = 1.0) noexcept
     465          21 :     : _M_max_load_factor(__z), _M_next_resize(0) { }
     466             : 
     467             :     float
     468             :     max_load_factor() const noexcept
     469             :     { return _M_max_load_factor; }
     470             : 
     471             :     // Return a bucket size no smaller than n.
     472             :     std::size_t
     473             :     _M_next_bkt(std::size_t __n) const;
     474             : 
     475             :     // Return a bucket count appropriate for n elements
     476             :     std::size_t
     477           1 :     _M_bkt_for_elements(std::size_t __n) const
     478           1 :     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
     479             : 
     480             :     // __n_bkt is current bucket count, __n_elt is current element count,
     481             :     // and __n_ins is number of elements to be inserted.  Do we need to
     482             :     // increase bucket count?  If so, return make_pair(true, n), where n
     483             :     // is the new bucket count.  If not, return make_pair(false, 0).
     484             :     std::pair<bool, std::size_t>
     485             :     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
     486             :                    std::size_t __n_ins) const;
     487             : 
     488             :     typedef std::size_t _State;
     489             : 
     490             :     _State
     491        1201 :     _M_state() const
     492        1201 :     { return _M_next_resize; }
     493             : 
     494             :     void
     495             :     _M_reset() noexcept
     496             :     { _M_next_resize = 0; }
     497             : 
     498             :     void
     499           0 :     _M_reset(_State __state)
     500           0 :     { _M_next_resize = __state; }
     501             : 
     502             :     static const std::size_t _S_growth_factor = 2;
     503             : 
     504             :     float               _M_max_load_factor;
     505             :     mutable std::size_t _M_next_resize;
     506             :   };
     507             : 
     508             :   /// Range hashing function assuming that second arg is a power of 2.
     509             :   struct _Mask_range_hashing
     510             :   {
     511             :     typedef std::size_t first_argument_type;
     512             :     typedef std::size_t second_argument_type;
     513             :     typedef std::size_t result_type;
     514             : 
     515             :     result_type
     516             :     operator()(first_argument_type __num,
     517             :                second_argument_type __den) const noexcept
     518             :     { return __num & (__den - 1); }
     519             :   };
     520             : 
     521             :   /// Compute closest power of 2.
     522             :   _GLIBCXX14_CONSTEXPR
     523             :   inline std::size_t
     524             :   __clp2(std::size_t __n) noexcept
     525             :   {
     526             : #if __SIZEOF_SIZE_T__ >= 8
     527             :     std::uint_fast64_t __x = __n;
     528             : #else
     529             :     std::uint_fast32_t __x = __n;
     530             : #endif
     531             :     // Algorithm from Hacker's Delight, Figure 3-3.
     532             :     __x = __x - 1;
     533             :     __x = __x | (__x >> 1);
     534             :     __x = __x | (__x >> 2);
     535             :     __x = __x | (__x >> 4);
     536             :     __x = __x | (__x >> 8);
     537             :     __x = __x | (__x >>16);
     538             : #if __SIZEOF_SIZE_T__ >= 8
     539             :     __x = __x | (__x >>32);
     540             : #endif
     541             :     return __x + 1;
     542             :   }
     543             : 
     544             :   /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
     545             :   /// operations.
     546             :   struct _Power2_rehash_policy
     547             :   {
     548             :     using __has_load_factor = std::true_type;
     549             : 
     550             :     _Power2_rehash_policy(float __z = 1.0) noexcept
     551             :     : _M_max_load_factor(__z), _M_next_resize(0) { }
     552             : 
     553             :     float
     554             :     max_load_factor() const noexcept
     555             :     { return _M_max_load_factor; }
     556             : 
     557             :     // Return a bucket size no smaller than n (as long as n is not above the
     558             :     // highest power of 2).
     559             :     std::size_t
     560             :     _M_next_bkt(std::size_t __n) noexcept
     561             :     {
     562             :       const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
     563             :       const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
     564             :       std::size_t __res = __clp2(__n);
     565             : 
     566             :       if (__res == __n)
     567             :         __res <<= 1;
     568             : 
     569             :       if (__res == 0)
     570             :         __res = __max_bkt;
     571             : 
     572             :       if (__res == __max_bkt)
     573             :         // Set next resize to the max value so that we never try to rehash again
     574             :         // as we already reach the biggest possible bucket number.
     575             :         // Note that it might result in max_load_factor not being respected.
     576             :         _M_next_resize = std::size_t(-1);
     577             :       else
     578             :         _M_next_resize
     579             :           = __builtin_ceil(__res * (long double)_M_max_load_factor);
     580             : 
     581             :       return __res;
     582             :     }
     583             : 
     584             :     // Return a bucket count appropriate for n elements
     585             :     std::size_t
     586             :     _M_bkt_for_elements(std::size_t __n) const noexcept
     587             :     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
     588             : 
     589             :     // __n_bkt is current bucket count, __n_elt is current element count,
     590             :     // and __n_ins is number of elements to be inserted.  Do we need to
     591             :     // increase bucket count?  If so, return make_pair(true, n), where n
     592             :     // is the new bucket count.  If not, return make_pair(false, 0).
     593             :     std::pair<bool, std::size_t>
     594             :     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
     595             :                    std::size_t __n_ins) noexcept
     596             :     {
     597             :       if (__n_elt + __n_ins >= _M_next_resize)
     598             :         {
     599             :           long double __min_bkts = (__n_elt + __n_ins)
     600             :                                         / (long double)_M_max_load_factor;
     601             :           if (__min_bkts >= __n_bkt)
     602             :             return std::make_pair(true,
     603             :               _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
     604             :                                                 __n_bkt * _S_growth_factor)));
     605             : 
     606             :           _M_next_resize
     607             :             = __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
     608             :           return std::make_pair(false, 0);
     609             :         }
     610             :       else
     611             :         return std::make_pair(false, 0);
     612             :     }
     613             : 
     614             :     typedef std::size_t _State;
     615             : 
     616             :     _State
     617             :     _M_state() const noexcept
     618             :     { return _M_next_resize; }
     619             : 
     620             :     void
     621             :     _M_reset() noexcept
     622             :     { _M_next_resize = 0; }
     623             : 
     624             :     void
     625             :     _M_reset(_State __state) noexcept
     626             :     { _M_next_resize = __state; }
     627             : 
     628             :     static const std::size_t _S_growth_factor = 2;
     629             : 
     630             :     float       _M_max_load_factor;
     631             :     std::size_t _M_next_resize;
     632             :   };
     633             : 
     634             :   // Base classes for std::_Hashtable.  We define these base classes
     635             :   // because in some cases we want to do different things depending on
     636             :   // the value of a policy class.  In some cases the policy class
     637             :   // affects which member functions and nested typedefs are defined;
     638             :   // we handle that by specializing base class templates.  Several of
     639             :   // the base class templates need to access other members of class
     640             :   // template _Hashtable, so we use a variant of the "Curiously
     641             :   // Recurring Template Pattern" (CRTP) technique.
     642             : 
     643             :   /**
     644             :    *  Primary class template _Map_base.
     645             :    *
     646             :    *  If the hashtable has a value type of the form pair<T1, T2> and a
     647             :    *  key extraction policy (_ExtractKey) that returns the first part
     648             :    *  of the pair, the hashtable gets a mapped_type typedef.  If it
     649             :    *  satisfies those criteria and also has unique keys, then it also
     650             :    *  gets an operator[].
     651             :    */
     652             :   template<typename _Key, typename _Value, typename _Alloc,
     653             :            typename _ExtractKey, typename _Equal,
     654             :            typename _H1, typename _H2, typename _Hash,
     655             :            typename _RehashPolicy, typename _Traits,
     656             :            bool _Unique_keys = _Traits::__unique_keys::value>
     657             :     struct _Map_base { };
     658             : 
     659             :   /// Partial specialization, __unique_keys set to false.
     660             :   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
     661             :            typename _H1, typename _H2, typename _Hash,
     662             :            typename _RehashPolicy, typename _Traits>
     663             :     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
     664             :                      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
     665             :     {
     666             :       using mapped_type = typename std::tuple_element<1, _Pair>::type;
     667             :     };
     668             : 
     669             :   /// Partial specialization, __unique_keys set to true.
     670             :   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
     671             :            typename _H1, typename _H2, typename _Hash,
     672             :            typename _RehashPolicy, typename _Traits>
     673             :     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
     674             :                      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
     675             :     {
     676             :     private:
     677             :       using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
     678             :                                                          _Select1st,
     679             :                                                         _Equal, _H1, _H2, _Hash,
     680             :                                                           _Traits>;
     681             : 
     682             :       using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
     683             :                                      _Select1st, _Equal,
     684             :                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
     685             : 
     686             :       using __hash_code = typename __hashtable_base::__hash_code;
     687             :       using __node_type = typename __hashtable_base::__node_type;
     688             : 
     689             :     public:
     690             :       using key_type = typename __hashtable_base::key_type;
     691             :       using iterator = typename __hashtable_base::iterator;
     692             :       using mapped_type = typename std::tuple_element<1, _Pair>::type;
     693             : 
     694             :       mapped_type&
     695             :       operator[](const key_type& __k);
     696             : 
     697             :       mapped_type&
     698             :       operator[](key_type&& __k);
     699             : 
     700             :       // _GLIBCXX_RESOLVE_LIB_DEFECTS
     701             :       // DR 761. unordered_map needs an at() member function.
     702             :       mapped_type&
     703             :       at(const key_type& __k);
     704             : 
     705             :       const mapped_type&
     706             :       at(const key_type& __k) const;
     707             :     };
     708             : 
     709             :   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
     710             :            typename _H1, typename _H2, typename _Hash,
     711             :            typename _RehashPolicy, typename _Traits>
     712             :     auto
     713        1194 :     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
     714             :               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
     715             :     operator[](const key_type& __k)
     716             :     -> mapped_type&
     717             :     {
     718        1194 :       __hashtable* __h = static_cast<__hashtable*>(this);
     719        1194 :       __hash_code __code = __h->_M_hash_code(__k);
     720        1194 :       std::size_t __n = __h->_M_bucket_index(__k, __code);
     721        1194 :       __node_type* __p = __h->_M_find_node(__n, __k, __code);
     722             : 
     723        1194 :       if (!__p)
     724             :         {
     725        1194 :           __p = __h->_M_allocate_node(std::piecewise_construct,
     726             :                                       std::tuple<const key_type&>(__k),
     727             :                                       std::tuple<>());
     728        1194 :           return __h->_M_insert_unique_node(__n, __code, __p)->second;
     729             :         }
     730             : 
     731           0 :       return __p->_M_v().second;
     732             :     }
     733             : 
     734             :   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
     735             :            typename _H1, typename _H2, typename _Hash,
     736             :            typename _RehashPolicy, typename _Traits>
     737             :     auto
     738             :     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
     739             :               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
     740             :     operator[](key_type&& __k)
     741             :     -> mapped_type&
     742             :     {
     743             :       __hashtable* __h = static_cast<__hashtable*>(this);
     744             :       __hash_code __code = __h->_M_hash_code(__k);
     745             :       std::size_t __n = __h->_M_bucket_index(__k, __code);
     746             :       __node_type* __p = __h->_M_find_node(__n, __k, __code);
     747             : 
     748             :       if (!__p)
     749             :         {
     750             :           __p = __h->_M_allocate_node(std::piecewise_construct,
     751             :                                       std::forward_as_tuple(std::move(__k)),
     752             :                                       std::tuple<>());
     753             :           return __h->_M_insert_unique_node(__n, __code, __p)->second;
     754             :         }
     755             : 
     756             :       return __p->_M_v().second;
     757             :     }
     758             : 
     759             :   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
     760             :            typename _H1, typename _H2, typename _Hash,
     761             :            typename _RehashPolicy, typename _Traits>
     762             :     auto
     763             :     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
     764             :               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
     765             :     at(const key_type& __k)
     766             :     -> mapped_type&
     767             :     {
     768             :       __hashtable* __h = static_cast<__hashtable*>(this);
     769             :       __hash_code __code = __h->_M_hash_code(__k);
     770             :       std::size_t __n = __h->_M_bucket_index(__k, __code);
     771             :       __node_type* __p = __h->_M_find_node(__n, __k, __code);
     772             : 
     773             :       if (!__p)
     774             :         __throw_out_of_range(__N("_Map_base::at"));
     775             :       return __p->_M_v().second;
     776             :     }
     777             : 
     778             :   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
     779             :            typename _H1, typename _H2, typename _Hash,
     780             :            typename _RehashPolicy, typename _Traits>
     781             :     auto
     782         200 :     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
     783             :               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
     784             :     at(const key_type& __k) const
     785             :     -> const mapped_type&
     786             :     {
     787         200 :       const __hashtable* __h = static_cast<const __hashtable*>(this);
     788         200 :       __hash_code __code = __h->_M_hash_code(__k);
     789         200 :       std::size_t __n = __h->_M_bucket_index(__k, __code);
     790         200 :       __node_type* __p = __h->_M_find_node(__n, __k, __code);
     791             : 
     792         200 :       if (!__p)
     793           0 :         __throw_out_of_range(__N("_Map_base::at"));
     794         200 :       return __p->_M_v().second;
     795             :     }
     796             : 
     797             :   /**
     798             :    *  Primary class template _Insert_base.
     799             :    *
     800             :    *  Defines @c insert member functions appropriate to all _Hashtables.
     801             :    */
     802             :   template<typename _Key, typename _Value, typename _Alloc,
     803             :            typename _ExtractKey, typename _Equal,
     804             :            typename _H1, typename _H2, typename _Hash,
     805             :            typename _RehashPolicy, typename _Traits>
     806             :     struct _Insert_base
     807             :     {
     808             :     protected:
     809             :       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
     810             :                                      _Equal, _H1, _H2, _Hash,
     811             :                                      _RehashPolicy, _Traits>;
     812             : 
     813             :       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
     814             :                                                _Equal, _H1, _H2, _Hash,
     815             :                                                _Traits>;
     816             : 
     817             :       using value_type = typename __hashtable_base::value_type;
     818             :       using iterator = typename __hashtable_base::iterator;
     819             :       using const_iterator =  typename __hashtable_base::const_iterator;
     820             :       using size_type = typename __hashtable_base::size_type;
     821             : 
     822             :       using __unique_keys = typename __hashtable_base::__unique_keys;
     823             :       using __ireturn_type = typename __hashtable_base::__ireturn_type;
     824             :       using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>;
     825             :       using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
     826             :       using __node_gen_type = _AllocNode<__node_alloc_type>;
     827             : 
     828             :       __hashtable&
     829           7 :       _M_conjure_hashtable()
     830           7 :       { return *(static_cast<__hashtable*>(this)); }
     831             : 
     832             :       template<typename _InputIterator, typename _NodeGetter>
     833             :         void
     834             :         _M_insert_range(_InputIterator __first, _InputIterator __last,
     835             :                         const _NodeGetter&);
     836             : 
     837             :     public:
     838             :       __ireturn_type
     839           7 :       insert(const value_type& __v)
     840             :       {
     841           7 :         __hashtable& __h = _M_conjure_hashtable();
     842           7 :         __node_gen_type __node_gen(__h);
     843           7 :         return __h._M_insert(__v, __node_gen, __unique_keys());
     844             :       }
     845             : 
     846             :       iterator
     847             :       insert(const_iterator __hint, const value_type& __v)
     848             :       {
     849             :         __hashtable& __h = _M_conjure_hashtable();
     850             :         __node_gen_type __node_gen(__h);        
     851             :         return __h._M_insert(__hint, __v, __node_gen, __unique_keys());
     852             :       }
     853             : 
     854             :       void
     855             :       insert(initializer_list<value_type> __l)
     856             :       { this->insert(__l.begin(), __l.end()); }
     857             : 
     858             :       template<typename _InputIterator>
     859             :         void
     860             :         insert(_InputIterator __first, _InputIterator __last)
     861             :         {
     862             :           __hashtable& __h = _M_conjure_hashtable();
     863             :           __node_gen_type __node_gen(__h);
     864             :           return _M_insert_range(__first, __last, __node_gen);
     865             :         }
     866             :     };
     867             : 
     868             :   template<typename _Key, typename _Value, typename _Alloc,
     869             :            typename _ExtractKey, typename _Equal,
     870             :            typename _H1, typename _H2, typename _Hash,
     871             :            typename _RehashPolicy, typename _Traits>
     872             :     template<typename _InputIterator, typename _NodeGetter>
     873             :       void
     874             :       _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
     875             :                     _RehashPolicy, _Traits>::
     876             :       _M_insert_range(_InputIterator __first, _InputIterator __last,
     877             :                       const _NodeGetter& __node_gen)
     878             :       {
     879             :         using __rehash_type = typename __hashtable::__rehash_type;
     880             :         using __rehash_state = typename __hashtable::__rehash_state;
     881             :         using pair_type = std::pair<bool, std::size_t>;
     882             : 
     883             :         size_type __n_elt = __detail::__distance_fw(__first, __last);
     884             : 
     885             :         __hashtable& __h = _M_conjure_hashtable();
     886             :         __rehash_type& __rehash = __h._M_rehash_policy;
     887             :         const __rehash_state& __saved_state = __rehash._M_state();
     888             :         pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
     889             :                                                         __h._M_element_count,
     890             :                                                         __n_elt);
     891             : 
     892             :         if (__do_rehash.first)
     893             :           __h._M_rehash(__do_rehash.second, __saved_state);
     894             : 
     895             :         for (; __first != __last; ++__first)
     896             :           __h._M_insert(*__first, __node_gen, __unique_keys());
     897             :       }
     898             : 
     899             :   /**
     900             :    *  Primary class template _Insert.
     901             :    *
     902             :    *  Defines @c insert member functions that depend on _Hashtable policies,
     903             :    *  via partial specializations.
     904             :    */
     905             :   template<typename _Key, typename _Value, typename _Alloc,
     906             :            typename _ExtractKey, typename _Equal,
     907             :            typename _H1, typename _H2, typename _Hash,
     908             :            typename _RehashPolicy, typename _Traits,
     909             :            bool _Constant_iterators = _Traits::__constant_iterators::value>
     910             :     struct _Insert;
     911             : 
     912             :   /// Specialization.
     913             :   template<typename _Key, typename _Value, typename _Alloc,
     914             :            typename _ExtractKey, typename _Equal,
     915             :            typename _H1, typename _H2, typename _Hash,
     916             :            typename _RehashPolicy, typename _Traits>
     917             :     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
     918             :                    _RehashPolicy, _Traits, true>
     919             :     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
     920             :                            _H1, _H2, _Hash, _RehashPolicy, _Traits>
     921             :     {
     922             :       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
     923             :                                         _Equal, _H1, _H2, _Hash,
     924             :                                         _RehashPolicy, _Traits>;
     925             : 
     926             :       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
     927             :                                                _Equal, _H1, _H2, _Hash,
     928             :                                                _Traits>;
     929             : 
     930             :       using value_type = typename __base_type::value_type;
     931             :       using iterator = typename __base_type::iterator;
     932             :       using const_iterator =  typename __base_type::const_iterator;
     933             : 
     934             :       using __unique_keys = typename __base_type::__unique_keys;
     935             :       using __ireturn_type = typename __hashtable_base::__ireturn_type;
     936             :       using __hashtable = typename __base_type::__hashtable;
     937             :       using __node_gen_type = typename __base_type::__node_gen_type;
     938             : 
     939             :       using __base_type::insert;
     940             : 
     941             :       __ireturn_type
     942             :       insert(value_type&& __v)
     943             :       {
     944             :         __hashtable& __h = this->_M_conjure_hashtable();
     945             :         __node_gen_type __node_gen(__h);
     946             :         return __h._M_insert(std::move(__v), __node_gen, __unique_keys());
     947             :       }
     948             : 
     949             :       iterator
     950             :       insert(const_iterator __hint, value_type&& __v)
     951             :       {
     952             :         __hashtable& __h = this->_M_conjure_hashtable();
     953             :         __node_gen_type __node_gen(__h);
     954             :         return __h._M_insert(__hint, std::move(__v), __node_gen,
     955             :                              __unique_keys());
     956             :       }
     957             :     };
     958             : 
     959             :   /// Specialization.
     960             :   template<typename _Key, typename _Value, typename _Alloc,
     961             :            typename _ExtractKey, typename _Equal,
     962             :            typename _H1, typename _H2, typename _Hash,
     963             :            typename _RehashPolicy, typename _Traits>
     964             :     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
     965             :                    _RehashPolicy, _Traits, false>
     966             :     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
     967             :                            _H1, _H2, _Hash, _RehashPolicy, _Traits>
     968             :     {
     969             :       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
     970             :                                        _Equal, _H1, _H2, _Hash,
     971             :                                        _RehashPolicy, _Traits>;
     972             :       using value_type = typename __base_type::value_type;
     973             :       using iterator = typename __base_type::iterator;
     974             :       using const_iterator =  typename __base_type::const_iterator;
     975             : 
     976             :       using __unique_keys = typename __base_type::__unique_keys;
     977             :       using __hashtable = typename __base_type::__hashtable;
     978             :       using __ireturn_type = typename __base_type::__ireturn_type;
     979             : 
     980             :       using __base_type::insert;
     981             : 
     982             :       template<typename _Pair>
     983             :         using __is_cons = std::is_constructible<value_type, _Pair&&>;
     984             : 
     985             :       template<typename _Pair>
     986             :         using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
     987             : 
     988             :       template<typename _Pair>
     989             :         using _IFconsp = typename _IFcons<_Pair>::type;
     990             : 
     991             :       template<typename _Pair, typename = _IFconsp<_Pair>>
     992             :         __ireturn_type
     993             :         insert(_Pair&& __v)
     994             :         {
     995             :           __hashtable& __h = this->_M_conjure_hashtable();
     996             :           return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
     997             :         }
     998             : 
     999             :       template<typename _Pair, typename = _IFconsp<_Pair>>
    1000             :         iterator
    1001             :         insert(const_iterator __hint, _Pair&& __v)
    1002             :         {
    1003             :           __hashtable& __h = this->_M_conjure_hashtable();
    1004             :           return __h._M_emplace(__hint, __unique_keys(),
    1005             :                                 std::forward<_Pair>(__v));
    1006             :         }
    1007             :    };
    1008             : 
    1009             :   template<typename _Policy>
    1010             :     using __has_load_factor = typename _Policy::__has_load_factor;
    1011             : 
    1012             :   /**
    1013             :    *  Primary class template  _Rehash_base.
    1014             :    *
    1015             :    *  Give hashtable the max_load_factor functions and reserve iff the
    1016             :    *  rehash policy supports it.
    1017             :   */
    1018             :   template<typename _Key, typename _Value, typename _Alloc,
    1019             :            typename _ExtractKey, typename _Equal,
    1020             :            typename _H1, typename _H2, typename _Hash,
    1021             :            typename _RehashPolicy, typename _Traits,
    1022             :            typename =
    1023             :              __detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>>
    1024             :     struct _Rehash_base;
    1025             : 
    1026             :   /// Specialization when rehash policy doesn't provide load factor management.
    1027             :   template<typename _Key, typename _Value, typename _Alloc,
    1028             :            typename _ExtractKey, typename _Equal,
    1029             :            typename _H1, typename _H2, typename _Hash,
    1030             :            typename _RehashPolicy, typename _Traits>
    1031             :     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1032             :                       _H1, _H2, _Hash, _RehashPolicy, _Traits,
    1033             :                       std::false_type>
    1034             :     {
    1035             :     };
    1036             : 
    1037             :   /// Specialization when rehash policy provide load factor management.
    1038             :   template<typename _Key, typename _Value, typename _Alloc,
    1039             :            typename _ExtractKey, typename _Equal,
    1040             :            typename _H1, typename _H2, typename _Hash,
    1041             :            typename _RehashPolicy, typename _Traits>
    1042             :     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1043             :                         _H1, _H2, _Hash, _RehashPolicy, _Traits,
    1044             :                         std::true_type>
    1045             :     {
    1046             :       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
    1047             :                                      _Equal, _H1, _H2, _Hash,
    1048             :                                      _RehashPolicy, _Traits>;
    1049             : 
    1050             :       float
    1051             :       max_load_factor() const noexcept
    1052             :       {
    1053             :         const __hashtable* __this = static_cast<const __hashtable*>(this);
    1054             :         return __this->__rehash_policy().max_load_factor();
    1055             :       }
    1056             : 
    1057             :       void
    1058             :       max_load_factor(float __z)
    1059             :       {
    1060             :         __hashtable* __this = static_cast<__hashtable*>(this);
    1061             :         __this->__rehash_policy(_RehashPolicy(__z));
    1062             :       }
    1063             : 
    1064             :       void
    1065             :       reserve(std::size_t __n)
    1066             :       {
    1067             :         __hashtable* __this = static_cast<__hashtable*>(this);
    1068             :         __this->rehash(__builtin_ceil(__n / max_load_factor()));
    1069             :       }
    1070             :     };
    1071             : 
    1072             :   /**
    1073             :    *  Primary class template _Hashtable_ebo_helper.
    1074             :    *
    1075             :    *  Helper class using EBO when it is not forbidden (the type is not
    1076             :    *  final) and when it is worth it (the type is empty.)
    1077             :    */
    1078             :   template<int _Nm, typename _Tp,
    1079             :            bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
    1080             :     struct _Hashtable_ebo_helper;
    1081             : 
    1082             :   /// Specialization using EBO.
    1083             :   template<int _Nm, typename _Tp>
    1084          21 :     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
    1085             :     : private _Tp
    1086             :     {
    1087          20 :       _Hashtable_ebo_helper() = default;
    1088             : 
    1089             :       template<typename _OtherTp>
    1090           5 :         _Hashtable_ebo_helper(_OtherTp&& __tp)
    1091           5 :           : _Tp(std::forward<_OtherTp>(__tp))
    1092           5 :         { }
    1093             : 
    1094             :       static const _Tp&
    1095       12768 :       _S_cget(const _Hashtable_ebo_helper& __eboh)
    1096       12768 :       { return static_cast<const _Tp&>(__eboh); }
    1097             : 
    1098             :       static _Tp&
    1099        5068 :       _S_get(_Hashtable_ebo_helper& __eboh)
    1100        5068 :       { return static_cast<_Tp&>(__eboh); }
    1101             :     };
    1102             : 
    1103             :   /// Specialization not using EBO.
    1104             :   template<int _Nm, typename _Tp>
    1105             :     struct _Hashtable_ebo_helper<_Nm, _Tp, false>
    1106             :     {
    1107             :       _Hashtable_ebo_helper() = default;
    1108             : 
    1109             :       template<typename _OtherTp>
    1110             :         _Hashtable_ebo_helper(_OtherTp&& __tp)
    1111             :           : _M_tp(std::forward<_OtherTp>(__tp))
    1112             :         { }
    1113             : 
    1114             :       static const _Tp&
    1115             :       _S_cget(const _Hashtable_ebo_helper& __eboh)
    1116             :       { return __eboh._M_tp; }
    1117             : 
    1118             :       static _Tp&
    1119             :       _S_get(_Hashtable_ebo_helper& __eboh)
    1120             :       { return __eboh._M_tp; }
    1121             : 
    1122             :     private:
    1123             :       _Tp _M_tp;
    1124             :     };
    1125             : 
    1126             :   /**
    1127             :    *  Primary class template _Local_iterator_base.
    1128             :    *
    1129             :    *  Base class for local iterators, used to iterate within a bucket
    1130             :    *  but not between buckets.
    1131             :    */
    1132             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1133             :            typename _H1, typename _H2, typename _Hash,
    1134             :            bool __cache_hash_code>
    1135             :     struct _Local_iterator_base;
    1136             : 
    1137             :   /**
    1138             :    *  Primary class template _Hash_code_base.
    1139             :    *
    1140             :    *  Encapsulates two policy issues that aren't quite orthogonal.
    1141             :    *   (1) the difference between using a ranged hash function and using
    1142             :    *       the combination of a hash function and a range-hashing function.
    1143             :    *       In the former case we don't have such things as hash codes, so
    1144             :    *       we have a dummy type as placeholder.
    1145             :    *   (2) Whether or not we cache hash codes.  Caching hash codes is
    1146             :    *       meaningless if we have a ranged hash function.
    1147             :    *
    1148             :    *  We also put the key extraction objects here, for convenience.
    1149             :    *  Each specialization derives from one or more of the template
    1150             :    *  parameters to benefit from Ebo. This is important as this type
    1151             :    *  is inherited in some cases by the _Local_iterator_base type used
    1152             :    *  to implement local_iterator and const_local_iterator. As with
    1153             :    *  any iterator type we prefer to make it as small as possible.
    1154             :    *
    1155             :    *  Primary template is unused except as a hook for specializations.
    1156             :    */
    1157             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1158             :            typename _H1, typename _H2, typename _Hash,
    1159             :            bool __cache_hash_code>
    1160             :     struct _Hash_code_base;
    1161             : 
    1162             :   /// Specialization: ranged hash function, no caching hash codes.  H1
    1163             :   /// and H2 are provided but ignored.  We define a dummy hash code type.
    1164             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1165             :            typename _H1, typename _H2, typename _Hash>
    1166             :     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
    1167             :     : private _Hashtable_ebo_helper<0, _ExtractKey>,
    1168             :       private _Hashtable_ebo_helper<1, _Hash>
    1169             :     {
    1170             :     private:
    1171             :       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
    1172             :       using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
    1173             : 
    1174             :     protected:
    1175             :       typedef void*                                     __hash_code;
    1176             :       typedef _Hash_node<_Value, false>                   __node_type;
    1177             : 
    1178             :       // We need the default constructor for the local iterators and _Hashtable
    1179             :       // default constructor.
    1180             :       _Hash_code_base() = default;
    1181             : 
    1182             :       _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
    1183             :                       const _Hash& __h)
    1184             :       : __ebo_extract_key(__ex), __ebo_hash(__h) { }
    1185             : 
    1186             :       __hash_code
    1187             :       _M_hash_code(const _Key& __key) const
    1188             :       { return 0; }
    1189             : 
    1190             :       std::size_t
    1191             :       _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
    1192             :       { return _M_ranged_hash()(__k, __n); }
    1193             : 
    1194             :       std::size_t
    1195             :       _M_bucket_index(const __node_type* __p, std::size_t __n) const
    1196             :         noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(),
    1197             :                                                    (std::size_t)0)) )
    1198             :       { return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); }
    1199             : 
    1200             :       void
    1201             :       _M_store_code(__node_type*, __hash_code) const
    1202             :       { }
    1203             : 
    1204             :       void
    1205             :       _M_copy_code(__node_type*, const __node_type*) const
    1206             :       { }
    1207             : 
    1208             :       void
    1209             :       _M_swap(_Hash_code_base& __x)
    1210             :       {
    1211             :         std::swap(_M_extract(), __x._M_extract());
    1212             :         std::swap(_M_ranged_hash(), __x._M_ranged_hash());
    1213             :       }
    1214             : 
    1215             :       const _ExtractKey&
    1216             :       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
    1217             : 
    1218             :       _ExtractKey&
    1219             :       _M_extract() { return __ebo_extract_key::_S_get(*this); }
    1220             : 
    1221             :       const _Hash&
    1222             :       _M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }
    1223             : 
    1224             :       _Hash&
    1225             :       _M_ranged_hash() { return __ebo_hash::_S_get(*this); }
    1226             :     };
    1227             : 
    1228             :   // No specialization for ranged hash function while caching hash codes.
    1229             :   // That combination is meaningless, and trying to do it is an error.
    1230             : 
    1231             :   /// Specialization: ranged hash function, cache hash codes.  This
    1232             :   /// combination is meaningless, so we provide only a declaration
    1233             :   /// and no definition.
    1234             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1235             :            typename _H1, typename _H2, typename _Hash>
    1236             :     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
    1237             : 
    1238             :   /// Specialization: hash function and range-hashing function, no
    1239             :   /// caching of hash codes.
    1240             :   /// Provides typedef and accessor required by C++ 11.
    1241             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1242             :            typename _H1, typename _H2>
    1243             :     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
    1244             :                            _Default_ranged_hash, false>
    1245             :     : private _Hashtable_ebo_helper<0, _ExtractKey>,
    1246             :       private _Hashtable_ebo_helper<1, _H1>,
    1247             :       private _Hashtable_ebo_helper<2, _H2>
    1248             :     {
    1249             :     private:
    1250             :       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
    1251             :       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
    1252             :       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
    1253             : 
    1254             :       // Gives the local iterator implementation access to _M_bucket_index().
    1255             :       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
    1256             :                                          _Default_ranged_hash, false>;
    1257             : 
    1258             :     public:
    1259             :       typedef _H1                                       hasher;
    1260             : 
    1261             :       hasher
    1262             :       hash_function() const
    1263             :       { return _M_h1(); }
    1264             : 
    1265             :     protected:
    1266             :       typedef std::size_t                               __hash_code;
    1267             :       typedef _Hash_node<_Value, false>                   __node_type;
    1268             : 
    1269             :       // We need the default constructor for the local iterators and _Hashtable
    1270             :       // default constructor.
    1271             :       _Hash_code_base() = default;
    1272             : 
    1273           1 :       _Hash_code_base(const _ExtractKey& __ex,
    1274             :                       const _H1& __h1, const _H2& __h2,
    1275             :                       const _Default_ranged_hash&)
    1276           1 :       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
    1277             : 
    1278             :       __hash_code
    1279        1613 :       _M_hash_code(const _Key& __k) const
    1280        1613 :       { return _M_h1()(__k); }
    1281             : 
    1282             :       std::size_t
    1283        1698 :       _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
    1284        1698 :       { return _M_h2()(__c, __n); }
    1285             : 
    1286             :       std::size_t
    1287        2935 :       _M_bucket_index(const __node_type* __p, std::size_t __n) const
    1288             :         noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>()))
    1289             :                   && noexcept(declval<const _H2&>()((__hash_code)0,
    1290             :                                                     (std::size_t)0)) )
    1291        2935 :       { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); }
    1292             : 
    1293             :       void
    1294        1201 :       _M_store_code(__node_type*, __hash_code) const
    1295        1201 :       { }
    1296             : 
    1297             :       void
    1298             :       _M_copy_code(__node_type*, const __node_type*) const
    1299             :       { }
    1300             : 
    1301             :       void
    1302             :       _M_swap(_Hash_code_base& __x)
    1303             :       {
    1304             :         std::swap(_M_extract(), __x._M_extract());
    1305             :         std::swap(_M_h1(), __x._M_h1());
    1306             :         std::swap(_M_h2(), __x._M_h2());
    1307             :       }
    1308             : 
    1309             :       const _ExtractKey&
    1310        3261 :       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
    1311             : 
    1312             :       _ExtractKey&
    1313          92 :       _M_extract() { return __ebo_extract_key::_S_get(*this); }
    1314             : 
    1315             :       const _H1&
    1316        4548 :       _M_h1() const { return __ebo_h1::_S_cget(*this); }
    1317             : 
    1318             :       _H1&
    1319             :       _M_h1() { return __ebo_h1::_S_get(*this); }
    1320             : 
    1321             :       const _H2&
    1322        4633 :       _M_h2() const { return __ebo_h2::_S_cget(*this); }
    1323             : 
    1324             :       _H2&
    1325             :       _M_h2() { return __ebo_h2::_S_get(*this); }
    1326             :     };
    1327             : 
    1328             :   /// Specialization: hash function and range-hashing function,
    1329             :   /// caching hash codes.  H is provided but ignored.  Provides
    1330             :   /// typedef and accessor required by C++ 11.
    1331             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1332             :            typename _H1, typename _H2>
    1333             :     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
    1334             :                            _Default_ranged_hash, true>
    1335             :     : private _Hashtable_ebo_helper<0, _ExtractKey>,
    1336             :       private _Hashtable_ebo_helper<1, _H1>,
    1337             :       private _Hashtable_ebo_helper<2, _H2>
    1338             :     {
    1339             :     private:
    1340             :       // Gives the local iterator implementation access to _M_h2().
    1341             :       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
    1342             :                                          _Default_ranged_hash, true>;
    1343             : 
    1344             :       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
    1345             :       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
    1346             :       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
    1347             : 
    1348             :     public:
    1349             :       typedef _H1                                       hasher;
    1350             : 
    1351             :       hasher
    1352             :       hash_function() const
    1353             :       { return _M_h1(); }
    1354             : 
    1355             :     protected:
    1356             :       typedef std::size_t                               __hash_code;
    1357             :       typedef _Hash_node<_Value, true>                    __node_type;
    1358             : 
    1359             :       // We need the default constructor for _Hashtable default constructor.
    1360             :       _Hash_code_base() = default;
    1361             :       _Hash_code_base(const _ExtractKey& __ex,
    1362             :                       const _H1& __h1, const _H2& __h2,
    1363             :                       const _Default_ranged_hash&)
    1364             :       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
    1365             : 
    1366             :       __hash_code
    1367             :       _M_hash_code(const _Key& __k) const
    1368             :       { return _M_h1()(__k); }
    1369             : 
    1370             :       std::size_t
    1371             :       _M_bucket_index(const _Key&, __hash_code __c,
    1372             :                       std::size_t __n) const
    1373             :       { return _M_h2()(__c, __n); }
    1374             : 
    1375             :       std::size_t
    1376             :       _M_bucket_index(const __node_type* __p, std::size_t __n) const
    1377             :         noexcept( noexcept(declval<const _H2&>()((__hash_code)0,
    1378             :                                                  (std::size_t)0)) )
    1379             :       { return _M_h2()(__p->_M_hash_code, __n); }
    1380             : 
    1381             :       void
    1382             :       _M_store_code(__node_type* __n, __hash_code __c) const
    1383             :       { __n->_M_hash_code = __c; }
    1384             : 
    1385             :       void
    1386             :       _M_copy_code(__node_type* __to, const __node_type* __from) const
    1387             :       { __to->_M_hash_code = __from->_M_hash_code; }
    1388             : 
    1389             :       void
    1390             :       _M_swap(_Hash_code_base& __x)
    1391             :       {
    1392             :         std::swap(_M_extract(), __x._M_extract());
    1393             :         std::swap(_M_h1(), __x._M_h1());
    1394             :         std::swap(_M_h2(), __x._M_h2());
    1395             :       }
    1396             : 
    1397             :       const _ExtractKey&
    1398             :       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
    1399             : 
    1400             :       _ExtractKey&
    1401             :       _M_extract() { return __ebo_extract_key::_S_get(*this); }
    1402             : 
    1403             :       const _H1&
    1404             :       _M_h1() const { return __ebo_h1::_S_cget(*this); }
    1405             : 
    1406             :       _H1&
    1407             :       _M_h1() { return __ebo_h1::_S_get(*this); }
    1408             : 
    1409             :       const _H2&
    1410             :       _M_h2() const { return __ebo_h2::_S_cget(*this); }
    1411             : 
    1412             :       _H2&
    1413             :       _M_h2() { return __ebo_h2::_S_get(*this); }
    1414             :     };
    1415             : 
    1416             :   /**
    1417             :    *  Primary class template _Equal_helper.
    1418             :    *
    1419             :    */
    1420             :   template <typename _Key, typename _Value, typename _ExtractKey,
    1421             :             typename _Equal, typename _HashCodeType,
    1422             :             bool __cache_hash_code>
    1423             :   struct _Equal_helper;
    1424             : 
    1425             :   /// Specialization.
    1426             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1427             :            typename _Equal, typename _HashCodeType>
    1428             :   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
    1429             :   {
    1430             :     static bool
    1431             :     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
    1432             :               const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
    1433             :     { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); }
    1434             :   };
    1435             : 
    1436             :   /// Specialization.
    1437             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1438             :            typename _Equal, typename _HashCodeType>
    1439             :   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
    1440             :   {
    1441             :     static bool
    1442         326 :     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
    1443             :               const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
    1444         326 :     { return __eq(__k, __extract(__n->_M_v())); }
    1445             :   };
    1446             : 
    1447             : 
    1448             :   /// Partial specialization used when nodes contain a cached hash code.
    1449             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1450             :            typename _H1, typename _H2, typename _Hash>
    1451             :     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
    1452             :                                 _H1, _H2, _Hash, true>
    1453             :     : private _Hashtable_ebo_helper<0, _H2>
    1454             :     {
    1455             :     protected:
    1456             :       using __base_type = _Hashtable_ebo_helper<0, _H2>;
    1457             :       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
    1458             :                                                _H1, _H2, _Hash, true>;
    1459             : 
    1460             :       _Local_iterator_base() = default;
    1461             :       _Local_iterator_base(const __hash_code_base& __base,
    1462             :                            _Hash_node<_Value, true>* __p,
    1463             :                            std::size_t __bkt, std::size_t __bkt_count)
    1464             :       : __base_type(__base._M_h2()),
    1465             :         _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
    1466             : 
    1467             :       void
    1468             :       _M_incr()
    1469             :       {
    1470             :         _M_cur = _M_cur->_M_next();
    1471             :         if (_M_cur)
    1472             :           {
    1473             :             std::size_t __bkt
    1474             :               = __base_type::_S_get(*this)(_M_cur->_M_hash_code,
    1475             :                                            _M_bucket_count);
    1476             :             if (__bkt != _M_bucket)
    1477             :               _M_cur = nullptr;
    1478             :           }
    1479             :       }
    1480             : 
    1481             :       _Hash_node<_Value, true>*  _M_cur;
    1482             :       std::size_t _M_bucket;
    1483             :       std::size_t _M_bucket_count;
    1484             : 
    1485             :     public:
    1486             :       const void*
    1487             :       _M_curr() const { return _M_cur; }  // for equality ops
    1488             : 
    1489             :       std::size_t
    1490             :       _M_get_bucket() const { return _M_bucket; }  // for debug mode
    1491             :     };
    1492             : 
    1493             :   // Uninitialized storage for a _Hash_code_base.
    1494             :   // This type is DefaultConstructible and Assignable even if the
    1495             :   // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
    1496             :   // can be DefaultConstructible and Assignable.
    1497             :   template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
    1498             :     struct _Hash_code_storage
    1499             :     {
    1500             :       __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
    1501             : 
    1502             :       _Tp*
    1503             :       _M_h() { return _M_storage._M_ptr(); }
    1504             : 
    1505             :       const _Tp*
    1506             :       _M_h() const { return _M_storage._M_ptr(); }
    1507             :     };
    1508             : 
    1509             :   // Empty partial specialization for empty _Hash_code_base types.
    1510             :   template<typename _Tp>
    1511             :     struct _Hash_code_storage<_Tp, true>
    1512             :     {
    1513             :       static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
    1514             : 
    1515             :       // As _Tp is an empty type there will be no bytes written/read through
    1516             :       // the cast pointer, so no strict-aliasing violation.
    1517             :       _Tp*
    1518             :       _M_h() { return reinterpret_cast<_Tp*>(this); }
    1519             : 
    1520             :       const _Tp*
    1521             :       _M_h() const { return reinterpret_cast<const _Tp*>(this); }
    1522             :     };
    1523             : 
    1524             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1525             :            typename _H1, typename _H2, typename _Hash>
    1526             :     using __hash_code_for_local_iter
    1527             :       = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
    1528             :                                            _H1, _H2, _Hash, false>>;
    1529             : 
    1530             :   // Partial specialization used when hash codes are not cached
    1531             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1532             :            typename _H1, typename _H2, typename _Hash>
    1533             :     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
    1534             :                                 _H1, _H2, _Hash, false>
    1535             :     : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash>
    1536             :     {
    1537             :     protected:
    1538             :       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
    1539             :                                                _H1, _H2, _Hash, false>;
    1540             : 
    1541             :       _Local_iterator_base() : _M_bucket_count(-1) { }
    1542             : 
    1543             :       _Local_iterator_base(const __hash_code_base& __base,
    1544             :                            _Hash_node<_Value, false>* __p,
    1545             :                            std::size_t __bkt, std::size_t __bkt_count)
    1546             :       : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
    1547             :       { _M_init(__base); }
    1548             : 
    1549             :       ~_Local_iterator_base()
    1550             :       {
    1551             :         if (_M_bucket_count != -1)
    1552             :           _M_destroy();
    1553             :       }
    1554             : 
    1555             :       _Local_iterator_base(const _Local_iterator_base& __iter)
    1556             :       : _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket),
    1557             :         _M_bucket_count(__iter._M_bucket_count)
    1558             :       {
    1559             :         if (_M_bucket_count != -1)
    1560             :           _M_init(*__iter._M_h());
    1561             :       }
    1562             : 
    1563             :       _Local_iterator_base&
    1564             :       operator=(const _Local_iterator_base& __iter)
    1565             :       {
    1566             :         if (_M_bucket_count != -1)
    1567             :           _M_destroy();
    1568             :         _M_cur = __iter._M_cur;
    1569             :         _M_bucket = __iter._M_bucket;
    1570             :         _M_bucket_count = __iter._M_bucket_count;
    1571             :         if (_M_bucket_count != -1)
    1572             :           _M_init(*__iter._M_h());
    1573             :         return *this;
    1574             :       }
    1575             : 
    1576             :       void
    1577             :       _M_incr()
    1578             :       {
    1579             :         _M_cur = _M_cur->_M_next();
    1580             :         if (_M_cur)
    1581             :           {
    1582             :             std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur,
    1583             :                                                               _M_bucket_count);
    1584             :             if (__bkt != _M_bucket)
    1585             :               _M_cur = nullptr;
    1586             :           }
    1587             :       }
    1588             : 
    1589             :       _Hash_node<_Value, false>*  _M_cur;
    1590             :       std::size_t _M_bucket;
    1591             :       std::size_t _M_bucket_count;
    1592             : 
    1593             :       void
    1594             :       _M_init(const __hash_code_base& __base)
    1595             :       { ::new(this->_M_h()) __hash_code_base(__base); }
    1596             : 
    1597             :       void
    1598             :       _M_destroy() { this->_M_h()->~__hash_code_base(); }
    1599             : 
    1600             :     public:
    1601             :       const void*
    1602             :       _M_curr() const { return _M_cur; }  // for equality ops and debug mode
    1603             : 
    1604             :       std::size_t
    1605             :       _M_get_bucket() const { return _M_bucket; }  // for debug mode
    1606             :     };
    1607             : 
    1608             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1609             :            typename _H1, typename _H2, typename _Hash, bool __cache>
    1610             :     inline bool
    1611             :     operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
    1612             :                                           _H1, _H2, _Hash, __cache>& __x,
    1613             :                const _Local_iterator_base<_Key, _Value, _ExtractKey,
    1614             :                                           _H1, _H2, _Hash, __cache>& __y)
    1615             :     { return __x._M_curr() == __y._M_curr(); }
    1616             : 
    1617             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1618             :            typename _H1, typename _H2, typename _Hash, bool __cache>
    1619             :     inline bool
    1620             :     operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
    1621             :                                           _H1, _H2, _Hash, __cache>& __x,
    1622             :                const _Local_iterator_base<_Key, _Value, _ExtractKey,
    1623             :                                           _H1, _H2, _Hash, __cache>& __y)
    1624             :     { return __x._M_curr() != __y._M_curr(); }
    1625             : 
    1626             :   /// local iterators
    1627             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1628             :            typename _H1, typename _H2, typename _Hash,
    1629             :            bool __constant_iterators, bool __cache>
    1630             :     struct _Local_iterator
    1631             :     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
    1632             :                                   _H1, _H2, _Hash, __cache>
    1633             :     {
    1634             :     private:
    1635             :       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
    1636             :                                                _H1, _H2, _Hash, __cache>;
    1637             :       using __hash_code_base = typename __base_type::__hash_code_base;
    1638             :     public:
    1639             :       typedef _Value                                    value_type;
    1640             :       typedef typename std::conditional<__constant_iterators,
    1641             :                                         const _Value*, _Value*>::type
    1642             :                                                        pointer;
    1643             :       typedef typename std::conditional<__constant_iterators,
    1644             :                                         const _Value&, _Value&>::type
    1645             :                                                        reference;
    1646             :       typedef std::ptrdiff_t                            difference_type;
    1647             :       typedef std::forward_iterator_tag                 iterator_category;
    1648             : 
    1649             :       _Local_iterator() = default;
    1650             : 
    1651             :       _Local_iterator(const __hash_code_base& __base,
    1652             :                       _Hash_node<_Value, __cache>* __p,
    1653             :                       std::size_t __bkt, std::size_t __bkt_count)
    1654             :         : __base_type(__base, __p, __bkt, __bkt_count)
    1655             :       { }
    1656             : 
    1657             :       reference
    1658             :       operator*() const
    1659             :       { return this->_M_cur->_M_v(); }
    1660             : 
    1661             :       pointer
    1662             :       operator->() const
    1663             :       { return this->_M_cur->_M_valptr(); }
    1664             : 
    1665             :       _Local_iterator&
    1666             :       operator++()
    1667             :       {
    1668             :         this->_M_incr();
    1669             :         return *this;
    1670             :       }
    1671             : 
    1672             :       _Local_iterator
    1673             :       operator++(int)
    1674             :       {
    1675             :         _Local_iterator __tmp(*this);
    1676             :         this->_M_incr();
    1677             :         return __tmp;
    1678             :       }
    1679             :     };
    1680             : 
    1681             :   /// local const_iterators
    1682             :   template<typename _Key, typename _Value, typename _ExtractKey,
    1683             :            typename _H1, typename _H2, typename _Hash,
    1684             :            bool __constant_iterators, bool __cache>
    1685             :     struct _Local_const_iterator
    1686             :     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
    1687             :                                   _H1, _H2, _Hash, __cache>
    1688             :     {
    1689             :     private:
    1690             :       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
    1691             :                                                _H1, _H2, _Hash, __cache>;
    1692             :       using __hash_code_base = typename __base_type::__hash_code_base;
    1693             : 
    1694             :     public:
    1695             :       typedef _Value                                    value_type;
    1696             :       typedef const _Value*                             pointer;
    1697             :       typedef const _Value&                         reference;
    1698             :       typedef std::ptrdiff_t                            difference_type;
    1699             :       typedef std::forward_iterator_tag                 iterator_category;
    1700             : 
    1701             :       _Local_const_iterator() = default;
    1702             : 
    1703             :       _Local_const_iterator(const __hash_code_base& __base,
    1704             :                             _Hash_node<_Value, __cache>* __p,
    1705             :                             std::size_t __bkt, std::size_t __bkt_count)
    1706             :         : __base_type(__base, __p, __bkt, __bkt_count)
    1707             :       { }
    1708             : 
    1709             :       _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
    1710             :                                                   _H1, _H2, _Hash,
    1711             :                                                   __constant_iterators,
    1712             :                                                   __cache>& __x)
    1713             :         : __base_type(__x)
    1714             :       { }
    1715             : 
    1716             :       reference
    1717             :       operator*() const
    1718             :       { return this->_M_cur->_M_v(); }
    1719             : 
    1720             :       pointer
    1721             :       operator->() const
    1722             :       { return this->_M_cur->_M_valptr(); }
    1723             : 
    1724             :       _Local_const_iterator&
    1725             :       operator++()
    1726             :       {
    1727             :         this->_M_incr();
    1728             :         return *this;
    1729             :       }
    1730             : 
    1731             :       _Local_const_iterator
    1732             :       operator++(int)
    1733             :       {
    1734             :         _Local_const_iterator __tmp(*this);
    1735             :         this->_M_incr();
    1736             :         return __tmp;
    1737             :       }
    1738             :     };
    1739             : 
    1740             :   /**
    1741             :    *  Primary class template _Hashtable_base.
    1742             :    *
    1743             :    *  Helper class adding management of _Equal functor to
    1744             :    *  _Hash_code_base type.
    1745             :    *
    1746             :    *  Base class templates are:
    1747             :    *    - __detail::_Hash_code_base
    1748             :    *    - __detail::_Hashtable_ebo_helper
    1749             :    */
    1750             :   template<typename _Key, typename _Value,
    1751             :            typename _ExtractKey, typename _Equal,
    1752             :            typename _H1, typename _H2, typename _Hash, typename _Traits>
    1753             :   struct _Hashtable_base
    1754             :   : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
    1755             :                            _Traits::__hash_cached::value>,
    1756             :     private _Hashtable_ebo_helper<0, _Equal>
    1757             :   {
    1758             :   public:
    1759             :     typedef _Key                                        key_type;
    1760             :     typedef _Value                                      value_type;
    1761             :     typedef _Equal                                      key_equal;
    1762             :     typedef std::size_t                                 size_type;
    1763             :     typedef std::ptrdiff_t                              difference_type;
    1764             : 
    1765             :     using __traits_type = _Traits;
    1766             :     using __hash_cached = typename __traits_type::__hash_cached;
    1767             :     using __constant_iterators = typename __traits_type::__constant_iterators;
    1768             :     using __unique_keys = typename __traits_type::__unique_keys;
    1769             : 
    1770             :     using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
    1771             :                                              _H1, _H2, _Hash,
    1772             :                                              __hash_cached::value>;
    1773             : 
    1774             :     using __hash_code = typename __hash_code_base::__hash_code;
    1775             :     using __node_type = typename __hash_code_base::__node_type;
    1776             : 
    1777             :     using iterator = __detail::_Node_iterator<value_type,
    1778             :                                               __constant_iterators::value,
    1779             :                                               __hash_cached::value>;
    1780             : 
    1781             :     using const_iterator = __detail::_Node_const_iterator<value_type,
    1782             :                                                    __constant_iterators::value,
    1783             :                                                    __hash_cached::value>;
    1784             : 
    1785             :     using local_iterator = __detail::_Local_iterator<key_type, value_type,
    1786             :                                                   _ExtractKey, _H1, _H2, _Hash,
    1787             :                                                   __constant_iterators::value,
    1788             :                                                      __hash_cached::value>;
    1789             : 
    1790             :     using const_local_iterator = __detail::_Local_const_iterator<key_type,
    1791             :                                                                  value_type,
    1792             :                                         _ExtractKey, _H1, _H2, _Hash,
    1793             :                                         __constant_iterators::value,
    1794             :                                         __hash_cached::value>;
    1795             : 
    1796             :     using __ireturn_type = typename std::conditional<__unique_keys::value,
    1797             :                                                      std::pair<iterator, bool>,
    1798             :                                                      iterator>::type;
    1799             :   private:
    1800             :     using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
    1801             :     using _EqualHelper =  _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
    1802             :                                         __hash_code, __hash_cached::value>;
    1803             : 
    1804             :   protected:
    1805             :     _Hashtable_base() = default;
    1806           1 :     _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
    1807             :                     const _Hash& __hash, const _Equal& __eq)
    1808           1 :     : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
    1809           1 :     { }
    1810             : 
    1811             :     bool
    1812         326 :     _M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
    1813             :     {
    1814         326 :       return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
    1815         326 :                                      __k, __c, __n);
    1816             :     }
    1817             : 
    1818             :     void
    1819             :     _M_swap(_Hashtable_base& __x)
    1820             :     {
    1821             :       __hash_code_base::_M_swap(__x);
    1822             :       std::swap(_M_eq(), __x._M_eq());
    1823             :     }
    1824             : 
    1825             :     const _Equal&
    1826         326 :     _M_eq() const { return _EqualEBO::_S_cget(*this); }
    1827             : 
    1828             :     _Equal&
    1829             :     _M_eq() { return _EqualEBO::_S_get(*this); }
    1830             :   };
    1831             : 
    1832             :   /**
    1833             :    *  struct _Equality_base.
    1834             :    *
    1835             :    *  Common types and functions for class _Equality.
    1836             :    */
    1837             :   struct _Equality_base
    1838             :   {
    1839             :   protected:
    1840             :     template<typename _Uiterator>
    1841             :       static bool
    1842             :       _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
    1843             :   };
    1844             : 
    1845             :   // See std::is_permutation in N3068.
    1846             :   template<typename _Uiterator>
    1847             :     bool
    1848             :     _Equality_base::
    1849             :     _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
    1850             :                       _Uiterator __first2)
    1851             :     {
    1852             :       for (; __first1 != __last1; ++__first1, ++__first2)
    1853             :         if (!(*__first1 == *__first2))
    1854             :           break;
    1855             : 
    1856             :       if (__first1 == __last1)
    1857             :         return true;
    1858             : 
    1859             :       _Uiterator __last2 = __first2;
    1860             :       std::advance(__last2, std::distance(__first1, __last1));
    1861             : 
    1862             :       for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
    1863             :         {
    1864             :           _Uiterator __tmp =  __first1;
    1865             :           while (__tmp != __it1 && !bool(*__tmp == *__it1))
    1866             :             ++__tmp;
    1867             : 
    1868             :           // We've seen this one before.
    1869             :           if (__tmp != __it1)
    1870             :             continue;
    1871             : 
    1872             :           std::ptrdiff_t __n2 = 0;
    1873             :           for (__tmp = __first2; __tmp != __last2; ++__tmp)
    1874             :             if (*__tmp == *__it1)
    1875             :               ++__n2;
    1876             : 
    1877             :           if (!__n2)
    1878             :             return false;
    1879             : 
    1880             :           std::ptrdiff_t __n1 = 0;
    1881             :           for (__tmp = __it1; __tmp != __last1; ++__tmp)
    1882             :             if (*__tmp == *__it1)
    1883             :               ++__n1;
    1884             : 
    1885             :           if (__n1 != __n2)
    1886             :             return false;
    1887             :         }
    1888             :       return true;
    1889             :     }
    1890             : 
    1891             :   /**
    1892             :    *  Primary class template  _Equality.
    1893             :    *
    1894             :    *  This is for implementing equality comparison for unordered
    1895             :    *  containers, per N3068, by John Lakos and Pablo Halpern.
    1896             :    *  Algorithmically, we follow closely the reference implementations
    1897             :    *  therein.
    1898             :    */
    1899             :   template<typename _Key, typename _Value, typename _Alloc,
    1900             :            typename _ExtractKey, typename _Equal,
    1901             :            typename _H1, typename _H2, typename _Hash,
    1902             :            typename _RehashPolicy, typename _Traits,
    1903             :            bool _Unique_keys = _Traits::__unique_keys::value>
    1904             :     struct _Equality;
    1905             : 
    1906             :   /// Specialization.
    1907             :   template<typename _Key, typename _Value, typename _Alloc,
    1908             :            typename _ExtractKey, typename _Equal,
    1909             :            typename _H1, typename _H2, typename _Hash,
    1910             :            typename _RehashPolicy, typename _Traits>
    1911             :     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1912             :                      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
    1913             :     {
    1914             :       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1915             :                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
    1916             : 
    1917             :       bool
    1918             :       _M_equal(const __hashtable&) const;
    1919             :     };
    1920             : 
    1921             :   template<typename _Key, typename _Value, typename _Alloc,
    1922             :            typename _ExtractKey, typename _Equal,
    1923             :            typename _H1, typename _H2, typename _Hash,
    1924             :            typename _RehashPolicy, typename _Traits>
    1925             :     bool
    1926             :     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1927             :               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    1928             :     _M_equal(const __hashtable& __other) const
    1929             :     {
    1930             :       const __hashtable* __this = static_cast<const __hashtable*>(this);
    1931             : 
    1932             :       if (__this->size() != __other.size())
    1933             :         return false;
    1934             : 
    1935             :       for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
    1936             :         {
    1937             :           const auto __ity = __other.find(_ExtractKey()(*__itx));
    1938             :           if (__ity == __other.end() || !bool(*__ity == *__itx))
    1939             :             return false;
    1940             :         }
    1941             :       return true;
    1942             :     }
    1943             : 
    1944             :   /// Specialization.
    1945             :   template<typename _Key, typename _Value, typename _Alloc,
    1946             :            typename _ExtractKey, typename _Equal,
    1947             :            typename _H1, typename _H2, typename _Hash,
    1948             :            typename _RehashPolicy, typename _Traits>
    1949             :     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1950             :                      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
    1951             :     : public _Equality_base
    1952             :     {
    1953             :       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1954             :                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
    1955             : 
    1956             :       bool
    1957             :       _M_equal(const __hashtable&) const;
    1958             :     };
    1959             : 
    1960             :   template<typename _Key, typename _Value, typename _Alloc,
    1961             :            typename _ExtractKey, typename _Equal,
    1962             :            typename _H1, typename _H2, typename _Hash,
    1963             :            typename _RehashPolicy, typename _Traits>
    1964             :     bool
    1965             :     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    1966             :               _H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
    1967             :     _M_equal(const __hashtable& __other) const
    1968             :     {
    1969             :       const __hashtable* __this = static_cast<const __hashtable*>(this);
    1970             : 
    1971             :       if (__this->size() != __other.size())
    1972             :         return false;
    1973             : 
    1974             :       for (auto __itx = __this->begin(); __itx != __this->end();)
    1975             :         {
    1976             :           const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
    1977             :           const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
    1978             : 
    1979             :           if (std::distance(__xrange.first, __xrange.second)
    1980             :               != std::distance(__yrange.first, __yrange.second))
    1981             :             return false;
    1982             : 
    1983             :           if (!_S_is_permutation(__xrange.first, __xrange.second,
    1984             :                                  __yrange.first))
    1985             :             return false;
    1986             : 
    1987             :           __itx = __xrange.second;
    1988             :         }
    1989             :       return true;
    1990             :     }
    1991             : 
    1992             :   /**
    1993             :    * This type deals with all allocation and keeps an allocator instance through
    1994             :    * inheritance to benefit from EBO when possible.
    1995             :    */
    1996             :   template<typename _NodeAlloc>
    1997          21 :     struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
    1998             :     {
    1999             :     private:
    2000             :       using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
    2001             :     public:
    2002             :       using __node_type = typename _NodeAlloc::value_type;
    2003             :       using __node_alloc_type = _NodeAlloc;
    2004             :       // Use __gnu_cxx to benefit from _S_always_equal and al.
    2005             :       using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
    2006             : 
    2007             :       using __value_type = typename __node_type::value_type;
    2008             :       using __value_alloc_type =
    2009             :         __alloc_rebind<__node_alloc_type, __value_type>;
    2010             :       using __value_alloc_traits = std::allocator_traits<__value_alloc_type>;
    2011             : 
    2012             :       using __node_base = __detail::_Hash_node_base;
    2013             :       using __bucket_type = __node_base*;      
    2014             :       using __bucket_alloc_type =
    2015             :         __alloc_rebind<__node_alloc_type, __bucket_type>;
    2016             :       using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>;
    2017             : 
    2018          20 :       _Hashtable_alloc() = default;
    2019             :       _Hashtable_alloc(const _Hashtable_alloc&) = default;
    2020             :       _Hashtable_alloc(_Hashtable_alloc&&) = default;
    2021             : 
    2022             :       template<typename _Alloc>
    2023           1 :         _Hashtable_alloc(_Alloc&& __a)
    2024           1 :           : __ebo_node_alloc(std::forward<_Alloc>(__a))
    2025           1 :         { }
    2026             : 
    2027             :       __node_alloc_type&
    2028        4976 :       _M_node_allocator()
    2029        4976 :       { return __ebo_node_alloc::_S_get(*this); }
    2030             : 
    2031             :       const __node_alloc_type&
    2032             :       _M_node_allocator() const
    2033             :       { return __ebo_node_alloc::_S_cget(*this); }
    2034             : 
    2035             :       template<typename... _Args>
    2036             :         __node_type*
    2037             :         _M_allocate_node(_Args&&... __args);
    2038             : 
    2039             :       void
    2040             :       _M_deallocate_node(__node_type* __n);
    2041             : 
    2042             :       // Deallocate the linked list of nodes pointed to by __n
    2043             :       void
    2044             :       _M_deallocate_nodes(__node_type* __n);
    2045             : 
    2046             :       __bucket_type*
    2047             :       _M_allocate_buckets(std::size_t __n);
    2048             : 
    2049             :       void
    2050             :       _M_deallocate_buckets(__bucket_type*, std::size_t __n);
    2051             :     };
    2052             : 
    2053             :   // Definitions of class template _Hashtable_alloc's out-of-line member
    2054             :   // functions.
    2055             :   template<typename _NodeAlloc>
    2056             :     template<typename... _Args>
    2057             :       typename _Hashtable_alloc<_NodeAlloc>::__node_type*
    2058        1201 :       _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
    2059             :       {
    2060        1201 :         auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
    2061        1201 :         __node_type* __n = std::__addressof(*__nptr);
    2062             :         __try
    2063             :           {
    2064        2402 :             __value_alloc_type __a(_M_node_allocator());
    2065        1201 :             ::new ((void*)__n) __node_type;
    2066        1201 :             __value_alloc_traits::construct(__a, __n->_M_valptr(),
    2067             :                                             std::forward<_Args>(__args)...);
    2068        2402 :             return __n;
    2069             :           }
    2070           0 :         __catch(...)
    2071             :           {
    2072           0 :             __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
    2073           0 :             __throw_exception_again;
    2074             :           }
    2075             :       }
    2076             : 
    2077             :   template<typename _NodeAlloc>
    2078             :     void
    2079        1201 :     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
    2080             :     {
    2081             :       typedef typename __node_alloc_traits::pointer _Ptr;
    2082        1201 :       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
    2083        2402 :       __value_alloc_type __a(_M_node_allocator());
    2084        1201 :       __value_alloc_traits::destroy(__a, __n->_M_valptr());
    2085             :       __n->~__node_type();
    2086        1201 :       __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
    2087        1201 :     }
    2088             : 
    2089             :   template<typename _NodeAlloc>
    2090             :     void
    2091        1222 :     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type* __n)
    2092             :     {
    2093        2423 :       while (__n)
    2094             :         {
    2095        1201 :           __node_type* __tmp = __n;
    2096        1201 :           __n = __n->_M_next();
    2097        1201 :           _M_deallocate_node(__tmp);
    2098             :         }
    2099          21 :     }
    2100             : 
    2101             :   template<typename _NodeAlloc>
    2102             :     typename _Hashtable_alloc<_NodeAlloc>::__bucket_type*
    2103          86 :     _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n)
    2104             :     {
    2105         172 :       __bucket_alloc_type __alloc(_M_node_allocator());
    2106             : 
    2107          86 :       auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
    2108          86 :       __bucket_type* __p = std::__addressof(*__ptr);
    2109          86 :       __builtin_memset(__p, 0, __n * sizeof(__bucket_type));
    2110         172 :       return __p;
    2111             :     }
    2112             : 
    2113             :   template<typename _NodeAlloc>
    2114             :     void
    2115          86 :     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts,
    2116             :                                                         std::size_t __n)
    2117             :     {
    2118             :       typedef typename __bucket_alloc_traits::pointer _Ptr;
    2119          86 :       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
    2120         172 :       __bucket_alloc_type __alloc(_M_node_allocator());
    2121          86 :       __bucket_alloc_traits::deallocate(__alloc, __ptr, __n);
    2122          86 :     }
    2123             : 
    2124             :  //@} hashtable-detail
    2125             : _GLIBCXX_END_NAMESPACE_VERSION
    2126             : } // namespace __detail
    2127             : } // namespace std
    2128             : 
    2129             : #endif // _HASHTABLE_POLICY_H

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