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      1 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
      2 
      3 // Copyright (C) 2010-2013 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 namespace std _GLIBCXX_VISIBILITY(default)
     35 {
     36 _GLIBCXX_BEGIN_NAMESPACE_VERSION
     37 
     38   template<typename _Key, typename _Value, typename _Alloc,
     39 	   typename _ExtractKey, typename _Equal,
     40 	   typename _H1, typename _H2, typename _Hash,
     41 	   typename _RehashPolicy, typename _Traits>
     42     class _Hashtable;
     43 
     44 _GLIBCXX_END_NAMESPACE_VERSION
     45 
     46 namespace __detail
     47 {
     48 _GLIBCXX_BEGIN_NAMESPACE_VERSION
     49 
     50   /**
     51    *  @defgroup hashtable-detail Base and Implementation Classes
     52    *  @ingroup unordered_associative_containers
     53    *  @{
     54    */
     55   template<typename _Key, typename _Value,
     56 	   typename _ExtractKey, typename _Equal,
     57 	   typename _H1, typename _H2, typename _Hash, typename _Traits>
     58     struct _Hashtable_base;
     59 
     60   // Helper function: return distance(first, last) for forward
     61   // iterators, or 0 for input iterators.
     62   template<class _Iterator>
     63     inline typename std::iterator_traits<_Iterator>::difference_type
     64     __distance_fw(_Iterator __first, _Iterator __last,
     65 		  std::input_iterator_tag)
     66     { return 0; }
     67 
     68   template<class _Iterator>
     69     inline typename std::iterator_traits<_Iterator>::difference_type
     70     __distance_fw(_Iterator __first, _Iterator __last,
     71 		  std::forward_iterator_tag)
     72     { return std::distance(__first, __last); }
     73 
     74   template<class _Iterator>
     75     inline typename std::iterator_traits<_Iterator>::difference_type
     76     __distance_fw(_Iterator __first, _Iterator __last)
     77     {
     78       typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag;
     79       return __distance_fw(__first, __last, _Tag());
     80     }
     81 
     82   // Helper type used to detect whether the hash functor is noexcept.
     83   template <typename _Key, typename _Hash>
     84     struct __is_noexcept_hash : std::integral_constant<bool,
     85 	noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
     86     { };
     87 
     88   struct _Identity
     89   {
     90     template<typename _Tp>
     91       _Tp&&
     92       operator()(_Tp&& __x) const
     93       { return std::forward<_Tp>(__x); }
     94   };
     95 
     96   struct _Select1st
     97   {
     98     template<typename _Tp>
     99       auto
    100       operator()(_Tp&& __x) const
    101       -> decltype(std::get<0>(std::forward<_Tp>(__x)))
    102       { return std::get<0>(std::forward<_Tp>(__x)); }
    103   };
    104 
    105   // Auxiliary types used for all instantiations of _Hashtable nodes
    106   // and iterators.
    107 
    108   /**
    109    *  struct _Hashtable_traits
    110    *
    111    *  Important traits for hash tables.
    112    *
    113    *  @tparam _Cache_hash_code  Boolean value. True if the value of
    114    *  the hash function is stored along with the value. This is a
    115    *  time-space tradeoff.  Storing it may improve lookup speed by
    116    *  reducing the number of times we need to call the _Equal
    117    *  function.
    118    *
    119    *  @tparam _Constant_iterators  Boolean value. True if iterator and
    120    *  const_iterator are both constant iterator types. This is true
    121    *  for unordered_set and unordered_multiset, false for
    122    *  unordered_map and unordered_multimap.
    123    *
    124    *  @tparam _Unique_keys  Boolean value. True if the return value
    125    *  of _Hashtable::count(k) is always at most one, false if it may
    126    *  be an arbitrary number. This is true for unordered_set and
    127    *  unordered_map, false for unordered_multiset and
    128    *  unordered_multimap.
    129    */
    130   template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
    131     struct _Hashtable_traits
    132     {
    133       template<bool _Cond>
    134 	using __bool_constant = integral_constant<bool, _Cond>;
    135 
    136       using __hash_cached = __bool_constant<_Cache_hash_code>;
    137       using __constant_iterators = __bool_constant<_Constant_iterators>;
    138       using __unique_keys = __bool_constant<_Unique_keys>;
    139     };
    140 
    141   /**
    142    *  struct _Hash_node_base
    143    *
    144    *  Nodes, used to wrap elements stored in the hash table.  A policy
    145    *  template parameter of class template _Hashtable controls whether
    146    *  nodes also store a hash code. In some cases (e.g. strings) this
    147    *  may be a performance win.
    148    */
    149   struct _Hash_node_base
    150   {
    151     _Hash_node_base* _M_nxt;
    152 
    153     _Hash_node_base() : _M_nxt() { }
    154 
    155     _Hash_node_base(_Hash_node_base* __next) : _M_nxt(__next) { }
    156   };
    157 
    158   /**
    159    *  Primary template struct _Hash_node.
    160    */
    161   template<typename _Value, bool _Cache_hash_code>
    162     struct _Hash_node;
    163 
    164   /**
    165    *  Specialization for nodes with caches, struct _Hash_node.
    166    *
    167    *  Base class is __detail::_Hash_node_base.
    168    */
    169   template<typename _Value>
    170     struct _Hash_node<_Value, true> : _Hash_node_base
    171     {
    172       _Value       _M_v;
    173       std::size_t  _M_hash_code;
    174 
    175       template<typename... _Args>
    176 	_Hash_node(_Args&&... __args)
    177 	: _M_v(std::forward<_Args>(__args)...), _M_hash_code() { }
    178 
    179       _Hash_node*
    180       _M_next() const { return static_cast<_Hash_node*>(_M_nxt); }
    181     };
    182 
    183   /**
    184    *  Specialization for nodes without caches, struct _Hash_node.
    185    *
    186    *  Base class is __detail::_Hash_node_base.
    187    */
    188   template<typename _Value>
    189     struct _Hash_node<_Value, false> : _Hash_node_base
    190     {
    191       _Value       _M_v;
    192 
    193       template<typename... _Args>
    194 	_Hash_node(_Args&&... __args)
    195 	: _M_v(std::forward<_Args>(__args)...) { }
    196 
    197       _Hash_node*
    198       _M_next() const { return static_cast<_Hash_node*>(_M_nxt); }
    199     };
    200 
    201   /// Base class for node iterators.
    202   template<typename _Value, bool _Cache_hash_code>
    203     struct _Node_iterator_base
    204     {
    205       using __node_type = _Hash_node<_Value, _Cache_hash_code>;
    206 
    207       __node_type*  _M_cur;
    208 
    209       _Node_iterator_base(__node_type* __p)
    210       : _M_cur(__p) { }
    211 
    212       void
    213       _M_incr()
    214       { _M_cur = _M_cur->_M_next(); }
    215     };
    216 
    217   template<typename _Value, bool _Cache_hash_code>
    218     inline bool
    219     operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
    220 	       const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
    221     { return __x._M_cur == __y._M_cur; }
    222 
    223   template<typename _Value, bool _Cache_hash_code>
    224     inline bool
    225     operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
    226 	       const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
    227     { return __x._M_cur != __y._M_cur; }
    228 
    229   /// Node iterators, used to iterate through all the hashtable.
    230   template<typename _Value, bool __constant_iterators, bool __cache>
    231     struct _Node_iterator
    232     : public _Node_iterator_base<_Value, __cache>
    233     {
    234     private:
    235       using __base_type = _Node_iterator_base<_Value, __cache>;
    236       using __node_type = typename __base_type::__node_type;
    237 
    238     public:
    239       typedef _Value                                   value_type;
    240       typedef std::ptrdiff_t                           difference_type;
    241       typedef std::forward_iterator_tag                iterator_category;
    242 
    243       using pointer = typename std::conditional<__constant_iterators,
    244 						const _Value*, _Value*>::type;
    245 
    246       using reference = typename std::conditional<__constant_iterators,
    247 						  const _Value&, _Value&>::type;
    248 
    249       _Node_iterator()
    250       : __base_type(0) { }
    251 
    252       explicit
    253       _Node_iterator(__node_type* __p)
    254       : __base_type(__p) { }
    255 
    256       reference
    257       operator*() const
    258       { return this->_M_cur->_M_v; }
    259 
    260       pointer
    261       operator->() const
    262       { return std::__addressof(this->_M_cur->_M_v); }
    263 
    264       _Node_iterator&
    265       operator++()
    266       {
    267 	this->_M_incr();
    268 	return *this;
    269       }
    270 
    271       _Node_iterator
    272       operator++(int)
    273       {
    274 	_Node_iterator __tmp(*this);
    275 	this->_M_incr();
    276 	return __tmp;
    277       }
    278     };
    279 
    280   /// Node const_iterators, used to iterate through all the hashtable.
    281   template<typename _Value, bool __constant_iterators, bool __cache>
    282     struct _Node_const_iterator
    283     : public _Node_iterator_base<_Value, __cache>
    284     {
    285     private:
    286       using __base_type = _Node_iterator_base<_Value, __cache>;
    287       using __node_type = typename __base_type::__node_type;
    288 
    289     public:
    290       typedef _Value                                   value_type;
    291       typedef std::ptrdiff_t                           difference_type;
    292       typedef std::forward_iterator_tag                iterator_category;
    293 
    294       typedef const _Value*                            pointer;
    295       typedef const _Value&                            reference;
    296 
    297       _Node_const_iterator()
    298       : __base_type(0) { }
    299 
    300       explicit
    301       _Node_const_iterator(__node_type* __p)
    302       : __base_type(__p) { }
    303 
    304       _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
    305 			   __cache>& __x)
    306       : __base_type(__x._M_cur) { }
    307 
    308       reference
    309       operator*() const
    310       { return this->_M_cur->_M_v; }
    311 
    312       pointer
    313       operator->() const
    314       { return std::__addressof(this->_M_cur->_M_v); }
    315 
    316       _Node_const_iterator&
    317       operator++()
    318       {
    319 	this->_M_incr();
    320 	return *this;
    321       }
    322 
    323       _Node_const_iterator
    324       operator++(int)
    325       {
    326 	_Node_const_iterator __tmp(*this);
    327 	this->_M_incr();
    328 	return __tmp;
    329       }
    330     };
    331 
    332   // Many of class template _Hashtable's template parameters are policy
    333   // classes.  These are defaults for the policies.
    334 
    335   /// Default range hashing function: use division to fold a large number
    336   /// into the range [0, N).
    337   struct _Mod_range_hashing
    338   {
    339     typedef std::size_t first_argument_type;
    340     typedef std::size_t second_argument_type;
    341     typedef std::size_t result_type;
    342 
    343     result_type
    344     operator()(first_argument_type __num, second_argument_type __den) const
    345     { return __num % __den; }
    346   };
    347 
    348   /// Default ranged hash function H.  In principle it should be a
    349   /// function object composed from objects of type H1 and H2 such that
    350   /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
    351   /// h1 and h2.  So instead we'll just use a tag to tell class template
    352   /// hashtable to do that composition.
    353   struct _Default_ranged_hash { };
    354 
    355   /// Default value for rehash policy.  Bucket size is (usually) the
    356   /// smallest prime that keeps the load factor small enough.
    357   struct _Prime_rehash_policy
    358   {
    359     _Prime_rehash_policy(float __z = 1.0)
    360     : _M_max_load_factor(__z), _M_next_resize(0) { }
    361 
    362     float
    363     max_load_factor() const noexcept
    364     { return _M_max_load_factor; }
    365 
    366     // Return a bucket size no smaller than n.
    367     std::size_t
    368     _M_next_bkt(std::size_t __n) const;
    369 
    370     // Return a bucket count appropriate for n elements
    371     std::size_t
    372     _M_bkt_for_elements(std::size_t __n) const
    373     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
    374 
    375     // __n_bkt is current bucket count, __n_elt is current element count,
    376     // and __n_ins is number of elements to be inserted.  Do we need to
    377     // increase bucket count?  If so, return make_pair(true, n), where n
    378     // is the new bucket count.  If not, return make_pair(false, 0).
    379     std::pair<bool, std::size_t>
    380     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
    381 		   std::size_t __n_ins) const;
    382 
    383     typedef std::size_t _State;
    384 
    385     _State
    386     _M_state() const
    387     { return _M_next_resize; }
    388 
    389     void
    390     _M_reset(_State __state)
    391     { _M_next_resize = __state; }
    392 
    393     enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 };
    394 
    395     static const std::size_t _S_growth_factor = 2;
    396 
    397     float                _M_max_load_factor;
    398     mutable std::size_t  _M_next_resize;
    399   };
    400 
    401   // Base classes for std::_Hashtable.  We define these base classes
    402   // because in some cases we want to do different things depending on
    403   // the value of a policy class.  In some cases the policy class
    404   // affects which member functions and nested typedefs are defined;
    405   // we handle that by specializing base class templates.  Several of
    406   // the base class templates need to access other members of class
    407   // template _Hashtable, so we use a variant of the "Curiously
    408   // Recurring Template Pattern" (CRTP) technique.
    409 
    410   /**
    411    *  Primary class template _Map_base.
    412    *
    413    *  If the hashtable has a value type of the form pair<T1, T2> and a
    414    *  key extraction policy (_ExtractKey) that returns the first part
    415    *  of the pair, the hashtable gets a mapped_type typedef.  If it
    416    *  satisfies those criteria and also has unique keys, then it also
    417    *  gets an operator[].
    418    */
    419   template<typename _Key, typename _Value, typename _Alloc,
    420 	   typename _ExtractKey, typename _Equal,
    421 	   typename _H1, typename _H2, typename _Hash,
    422 	   typename _RehashPolicy, typename _Traits,
    423 	   bool _Unique_keys = _Traits::__unique_keys::value>
    424     struct _Map_base { };
    425 
    426   /// Partial specialization, __unique_keys set to false.
    427   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
    428 	   typename _H1, typename _H2, typename _Hash,
    429 	   typename _RehashPolicy, typename _Traits>
    430     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    431 		     _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
    432     {
    433       using mapped_type = typename std::tuple_element<1, _Pair>::type;
    434     };
    435 
    436   /// Partial specialization, __unique_keys set to true.
    437   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
    438 	   typename _H1, typename _H2, typename _Hash,
    439 	   typename _RehashPolicy, typename _Traits>
    440     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    441 		     _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
    442     {
    443     private:
    444       using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
    445 							 _Select1st,
    446 							_Equal, _H1, _H2, _Hash,
    447 							  _Traits>;
    448 
    449       using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
    450 				     _Select1st, _Equal,
    451 				     _H1, _H2, _Hash, _RehashPolicy, _Traits>;
    452 
    453       using __hash_code = typename __hashtable_base::__hash_code;
    454       using __node_type = typename __hashtable_base::__node_type;
    455 
    456     public:
    457       using key_type = typename __hashtable_base::key_type;
    458       using iterator = typename __hashtable_base::iterator;
    459       using mapped_type = typename std::tuple_element<1, _Pair>::type;
    460 
    461       mapped_type&
    462       operator[](const key_type& __k);
    463 
    464       mapped_type&
    465       operator[](key_type&& __k);
    466 
    467       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    468       // DR 761. unordered_map needs an at() member function.
    469       mapped_type&
    470       at(const key_type& __k);
    471 
    472       const mapped_type&
    473       at(const key_type& __k) const;
    474     };
    475 
    476   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
    477 	   typename _H1, typename _H2, typename _Hash,
    478 	   typename _RehashPolicy, typename _Traits>
    479     typename _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    480 		       _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
    481 		       ::mapped_type&
    482     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    483 	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    484     operator[](const key_type& __k)
    485     {
    486       __hashtable* __h = static_cast<__hashtable*>(this);
    487       __hash_code __code = __h->_M_hash_code(__k);
    488       std::size_t __n = __h->_M_bucket_index(__k, __code);
    489       __node_type* __p = __h->_M_find_node(__n, __k, __code);
    490 
    491       if (!__p)
    492 	{
    493 	  __p = __h->_M_allocate_node(std::piecewise_construct,
    494 				      std::tuple<const key_type&>(__k),
    495 				      std::tuple<>());
    496 	  return __h->_M_insert_unique_node(__n, __code, __p)->second;
    497 	}
    498 
    499       return (__p->_M_v).second;
    500     }
    501 
    502   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
    503 	   typename _H1, typename _H2, typename _Hash,
    504 	   typename _RehashPolicy, typename _Traits>
    505     typename _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    506 		       _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
    507 		       ::mapped_type&
    508     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    509 	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    510     operator[](key_type&& __k)
    511     {
    512       __hashtable* __h = static_cast<__hashtable*>(this);
    513       __hash_code __code = __h->_M_hash_code(__k);
    514       std::size_t __n = __h->_M_bucket_index(__k, __code);
    515       __node_type* __p = __h->_M_find_node(__n, __k, __code);
    516 
    517       if (!__p)
    518 	{
    519 	  __p = __h->_M_allocate_node(std::piecewise_construct,
    520 				      std::forward_as_tuple(std::move(__k)),
    521 				      std::tuple<>());
    522 	  return __h->_M_insert_unique_node(__n, __code, __p)->second;
    523 	}
    524 
    525       return (__p->_M_v).second;
    526     }
    527 
    528   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
    529 	   typename _H1, typename _H2, typename _Hash,
    530 	   typename _RehashPolicy, typename _Traits>
    531     typename _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    532 		       _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
    533 		       ::mapped_type&
    534     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    535 	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    536     at(const key_type& __k)
    537     {
    538       __hashtable* __h = static_cast<__hashtable*>(this);
    539       __hash_code __code = __h->_M_hash_code(__k);
    540       std::size_t __n = __h->_M_bucket_index(__k, __code);
    541       __node_type* __p = __h->_M_find_node(__n, __k, __code);
    542 
    543       if (!__p)
    544 	__throw_out_of_range(__N("_Map_base::at"));
    545       return (__p->_M_v).second;
    546     }
    547 
    548   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
    549 	   typename _H1, typename _H2, typename _Hash,
    550 	   typename _RehashPolicy, typename _Traits>
    551     const typename _Map_base<_Key, _Pair, _Alloc, _Select1st,
    552 			     _Equal, _H1, _H2, _Hash, _RehashPolicy,
    553 			     _Traits, true>::mapped_type&
    554     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
    555 	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
    556     at(const key_type& __k) const
    557     {
    558       const __hashtable* __h = static_cast<const __hashtable*>(this);
    559       __hash_code __code = __h->_M_hash_code(__k);
    560       std::size_t __n = __h->_M_bucket_index(__k, __code);
    561       __node_type* __p = __h->_M_find_node(__n, __k, __code);
    562 
    563       if (!__p)
    564 	__throw_out_of_range(__N("_Map_base::at"));
    565       return (__p->_M_v).second;
    566     }
    567 
    568   /**
    569    *  Primary class template _Insert_base.
    570    *
    571    *  insert member functions appropriate to all _Hashtables.
    572    */
    573   template<typename _Key, typename _Value, typename _Alloc,
    574 	   typename _ExtractKey, typename _Equal,
    575 	   typename _H1, typename _H2, typename _Hash,
    576 	   typename _RehashPolicy, typename _Traits>
    577     struct _Insert_base
    578     {
    579       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
    580 				     _Equal, _H1, _H2, _Hash,
    581 				     _RehashPolicy, _Traits>;
    582 
    583       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
    584 					       _Equal, _H1, _H2, _Hash,
    585 					       _Traits>;
    586 
    587       using value_type = typename __hashtable_base::value_type;
    588       using iterator = typename __hashtable_base::iterator;
    589       using const_iterator =  typename __hashtable_base::const_iterator;
    590       using size_type = typename __hashtable_base::size_type;
    591 
    592       using __unique_keys = typename __hashtable_base::__unique_keys;
    593       using __ireturn_type = typename __hashtable_base::__ireturn_type;
    594       using __iconv_type = typename __hashtable_base::__iconv_type;
    595 
    596       __hashtable&
    597       _M_conjure_hashtable()
    598       { return *(static_cast<__hashtable*>(this)); }
    599 
    600       __ireturn_type
    601       insert(const value_type& __v)
    602       {
    603 	__hashtable& __h = _M_conjure_hashtable();
    604 	return __h._M_insert(__v, __unique_keys());
    605       }
    606 
    607       iterator
    608       insert(const_iterator, const value_type& __v)
    609       { return __iconv_type()(insert(__v)); }
    610 
    611       void
    612       insert(initializer_list<value_type> __l)
    613       { this->insert(__l.begin(), __l.end()); }
    614 
    615       template<typename _InputIterator>
    616 	void
    617 	insert(_InputIterator __first, _InputIterator __last);
    618     };
    619 
    620   template<typename _Key, typename _Value, typename _Alloc,
    621 	   typename _ExtractKey, typename _Equal,
    622 	   typename _H1, typename _H2, typename _Hash,
    623 	   typename _RehashPolicy, typename _Traits>
    624     template<typename _InputIterator>
    625       void
    626       _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
    627 		    _RehashPolicy, _Traits>::
    628       insert(_InputIterator __first, _InputIterator __last)
    629       {
    630 	using __rehash_type = typename __hashtable::__rehash_type;
    631 	using __rehash_state = typename __hashtable::__rehash_state;
    632 	using pair_type = std::pair<bool, std::size_t>;
    633 
    634 	size_type __n_elt = __detail::__distance_fw(__first, __last);
    635 
    636 	__hashtable& __h = _M_conjure_hashtable();
    637 	__rehash_type& __rehash = __h._M_rehash_policy;
    638 	const __rehash_state& __saved_state = __rehash._M_state();
    639 	pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
    640 							__h._M_element_count,
    641 							__n_elt);
    642 
    643 	if (__do_rehash.first)
    644 	  __h._M_rehash(__do_rehash.second, __saved_state);
    645 
    646 	for (; __first != __last; ++__first)
    647 	  this->insert(*__first);
    648       }
    649 
    650   /**
    651    *  Primary class template _Insert.
    652    *
    653    *  Select insert member functions appropriate to _Hashtable policy choices.
    654    */
    655   template<typename _Key, typename _Value, typename _Alloc,
    656 	   typename _ExtractKey, typename _Equal,
    657 	   typename _H1, typename _H2, typename _Hash,
    658 	   typename _RehashPolicy, typename _Traits,
    659 	   bool _Constant_iterators = _Traits::__constant_iterators::value,
    660 	   bool _Unique_keys = _Traits::__unique_keys::value>
    661     struct _Insert;
    662 
    663   /// Specialization.
    664   template<typename _Key, typename _Value, typename _Alloc,
    665 	   typename _ExtractKey, typename _Equal,
    666 	   typename _H1, typename _H2, typename _Hash,
    667 	   typename _RehashPolicy, typename _Traits>
    668     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
    669 		   _RehashPolicy, _Traits, true, true>
    670     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    671 			   _H1, _H2, _Hash, _RehashPolicy, _Traits>
    672     {
    673       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
    674 					_Equal, _H1, _H2, _Hash,
    675 					_RehashPolicy, _Traits>;
    676       using value_type = typename __base_type::value_type;
    677       using iterator = typename __base_type::iterator;
    678       using const_iterator =  typename __base_type::const_iterator;
    679 
    680       using __unique_keys = typename __base_type::__unique_keys;
    681       using __hashtable = typename __base_type::__hashtable;
    682 
    683       using __base_type::insert;
    684 
    685       std::pair<iterator, bool>
    686       insert(value_type&& __v)
    687       {
    688 	__hashtable& __h = this->_M_conjure_hashtable();
    689 	return __h._M_insert(std::move(__v), __unique_keys());
    690       }
    691 
    692       iterator
    693       insert(const_iterator, value_type&& __v)
    694       { return insert(std::move(__v)).first; }
    695     };
    696 
    697   /// Specialization.
    698   template<typename _Key, typename _Value, typename _Alloc,
    699 	   typename _ExtractKey, typename _Equal,
    700 	   typename _H1, typename _H2, typename _Hash,
    701 	   typename _RehashPolicy, typename _Traits>
    702     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
    703 		   _RehashPolicy, _Traits, true, false>
    704     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    705 			   _H1, _H2, _Hash, _RehashPolicy, _Traits>
    706     {
    707       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
    708 					_Equal, _H1, _H2, _Hash,
    709 					_RehashPolicy, _Traits>;
    710       using value_type = typename __base_type::value_type;
    711       using iterator = typename __base_type::iterator;
    712       using const_iterator =  typename __base_type::const_iterator;
    713 
    714       using __unique_keys = typename __base_type::__unique_keys;
    715       using __hashtable = typename __base_type::__hashtable;
    716 
    717       using __base_type::insert;
    718 
    719       iterator
    720       insert(value_type&& __v)
    721       {
    722 	__hashtable& __h = this->_M_conjure_hashtable();
    723 	return __h._M_insert(std::move(__v), __unique_keys());
    724       }
    725 
    726       iterator
    727       insert(const_iterator, value_type&& __v)
    728       { return insert(std::move(__v)); }
    729      };
    730 
    731   /// Specialization.
    732   template<typename _Key, typename _Value, typename _Alloc,
    733 	   typename _ExtractKey, typename _Equal,
    734 	   typename _H1, typename _H2, typename _Hash,
    735 	   typename _RehashPolicy, typename _Traits, bool _Unique_keys>
    736     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
    737 		   _RehashPolicy, _Traits, false, _Unique_keys>
    738     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    739 			   _H1, _H2, _Hash, _RehashPolicy, _Traits>
    740     {
    741       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
    742 				       _Equal, _H1, _H2, _Hash,
    743 				       _RehashPolicy, _Traits>;
    744       using value_type = typename __base_type::value_type;
    745       using iterator = typename __base_type::iterator;
    746       using const_iterator =  typename __base_type::const_iterator;
    747 
    748       using __unique_keys = typename __base_type::__unique_keys;
    749       using __hashtable = typename __base_type::__hashtable;
    750       using __ireturn_type = typename __base_type::__ireturn_type;
    751       using __iconv_type = typename __base_type::__iconv_type;
    752 
    753       using __base_type::insert;
    754 
    755       template<typename _Pair>
    756 	using __is_cons = std::is_constructible<value_type, _Pair&&>;
    757 
    758       template<typename _Pair>
    759 	using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
    760 
    761       template<typename _Pair>
    762 	using _IFconsp = typename _IFcons<_Pair>::type;
    763 
    764       template<typename _Pair, typename = _IFconsp<_Pair>>
    765 	__ireturn_type
    766 	insert(_Pair&& __v)
    767 	{
    768 	  __hashtable& __h = this->_M_conjure_hashtable();
    769 	  return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
    770 	}
    771 
    772       template<typename _Pair, typename = _IFconsp<_Pair>>
    773 	iterator
    774 	insert(const_iterator, _Pair&& __v)
    775 	{ return __iconv_type()(insert(std::forward<_Pair>(__v))); }
    776    };
    777 
    778   /**
    779    *  Primary class template  _Rehash_base.
    780    *
    781    *  Give hashtable the max_load_factor functions and reserve iff the
    782    *  rehash policy is _Prime_rehash_policy.
    783   */
    784   template<typename _Key, typename _Value, typename _Alloc,
    785 	   typename _ExtractKey, typename _Equal,
    786 	   typename _H1, typename _H2, typename _Hash,
    787 	   typename _RehashPolicy, typename _Traits>
    788     struct _Rehash_base;
    789 
    790   /// Specialization.
    791   template<typename _Key, typename _Value, typename _Alloc,
    792 	   typename _ExtractKey, typename _Equal,
    793 	   typename _H1, typename _H2, typename _Hash, typename _Traits>
    794     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
    795 			_H1, _H2, _Hash, _Prime_rehash_policy, _Traits>
    796     {
    797       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
    798 				     _Equal, _H1, _H2, _Hash,
    799 				     _Prime_rehash_policy, _Traits>;
    800 
    801       float
    802       max_load_factor() const noexcept
    803       {
    804 	const __hashtable* __this = static_cast<const __hashtable*>(this);
    805 	return __this->__rehash_policy().max_load_factor();
    806       }
    807 
    808       void
    809       max_load_factor(float __z)
    810       {
    811 	__hashtable* __this = static_cast<__hashtable*>(this);
    812 	__this->__rehash_policy(_Prime_rehash_policy(__z));
    813       }
    814 
    815       void
    816       reserve(std::size_t __n)
    817       {
    818 	__hashtable* __this = static_cast<__hashtable*>(this);
    819 	__this->rehash(__builtin_ceil(__n / max_load_factor()));
    820       }
    821     };
    822 
    823   /**
    824    *  Primary class template _Hashtable_ebo_helper.
    825    *
    826    *  Helper class using EBO when it is not forbidden, type is not
    827    *  final, and when it worth it, type is empty.
    828    */
    829   template<int _Nm, typename _Tp,
    830 	   bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
    831     struct _Hashtable_ebo_helper;
    832 
    833   /// Specialization using EBO.
    834   template<int _Nm, typename _Tp>
    835     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
    836     : private _Tp
    837     {
    838       _Hashtable_ebo_helper() = default;
    839 
    840       _Hashtable_ebo_helper(const _Tp& __tp) : _Tp(__tp)
    841       { }
    842 
    843       static const _Tp&
    844       _S_cget(const _Hashtable_ebo_helper& __eboh)
    845       { return static_cast<const _Tp&>(__eboh); }
    846 
    847       static _Tp&
    848       _S_get(_Hashtable_ebo_helper& __eboh)
    849       { return static_cast<_Tp&>(__eboh); }
    850     };
    851 
    852   /// Specialization not using EBO.
    853   template<int _Nm, typename _Tp>
    854     struct _Hashtable_ebo_helper<_Nm, _Tp, false>
    855     {
    856       _Hashtable_ebo_helper() = default;
    857 
    858       _Hashtable_ebo_helper(const _Tp& __tp) : _M_tp(__tp)
    859       { }
    860 
    861       static const _Tp&
    862       _S_cget(const _Hashtable_ebo_helper& __eboh)
    863       { return __eboh._M_tp; }
    864 
    865       static _Tp&
    866       _S_get(_Hashtable_ebo_helper& __eboh)
    867       { return __eboh._M_tp; }
    868 
    869     private:
    870       _Tp _M_tp;
    871     };
    872 
    873   /**
    874    *  Primary class template _Local_iterator_base.
    875    *
    876    *  Base class for local iterators, used to iterate within a bucket
    877    *  but not between buckets.
    878    */
    879   template<typename _Key, typename _Value, typename _ExtractKey,
    880 	   typename _H1, typename _H2, typename _Hash,
    881 	   bool __cache_hash_code>
    882     struct _Local_iterator_base;
    883 
    884   /**
    885    *  Primary class template _Hash_code_base.
    886    *
    887    *  Encapsulates two policy issues that aren't quite orthogonal.
    888    *   (1) the difference between using a ranged hash function and using
    889    *       the combination of a hash function and a range-hashing function.
    890    *       In the former case we don't have such things as hash codes, so
    891    *       we have a dummy type as placeholder.
    892    *   (2) Whether or not we cache hash codes.  Caching hash codes is
    893    *       meaningless if we have a ranged hash function.
    894    *
    895    *  We also put the key extraction objects here, for convenience.
    896    *  Each specialization derives from one or more of the template
    897    *  parameters to benefit from Ebo. This is important as this type
    898    *  is inherited in some cases by the _Local_iterator_base type used
    899    *  to implement local_iterator and const_local_iterator. As with
    900    *  any iterator type we prefer to make it as small as possible.
    901    *
    902    *  Primary template is unused except as a hook for specializations.
    903    */
    904   template<typename _Key, typename _Value, typename _ExtractKey,
    905 	   typename _H1, typename _H2, typename _Hash,
    906 	   bool __cache_hash_code>
    907     struct _Hash_code_base;
    908 
    909   /// Specialization: ranged hash function, no caching hash codes.  H1
    910   /// and H2 are provided but ignored.  We define a dummy hash code type.
    911   template<typename _Key, typename _Value, typename _ExtractKey,
    912 	   typename _H1, typename _H2, typename _Hash>
    913     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
    914     : private _Hashtable_ebo_helper<0, _ExtractKey>,
    915       private _Hashtable_ebo_helper<1, _Hash>
    916     {
    917     private:
    918       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
    919       using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
    920 
    921     protected:
    922       typedef void* 					__hash_code;
    923       typedef _Hash_node<_Value, false>			__node_type;
    924 
    925       // We need the default constructor for the local iterators.
    926       _Hash_code_base() = default;
    927 
    928       _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
    929 		      const _Hash& __h)
    930       : __ebo_extract_key(__ex), __ebo_hash(__h) { }
    931 
    932       __hash_code
    933       _M_hash_code(const _Key& __key) const
    934       { return 0; }
    935 
    936       std::size_t
    937       _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
    938       { return _M_ranged_hash()(__k, __n); }
    939 
    940       std::size_t
    941       _M_bucket_index(const __node_type* __p, std::size_t __n) const
    942       { return _M_ranged_hash()(_M_extract()(__p->_M_v), __n); }
    943 
    944       void
    945       _M_store_code(__node_type*, __hash_code) const
    946       { }
    947 
    948       void
    949       _M_copy_code(__node_type*, const __node_type*) const
    950       { }
    951 
    952       void
    953       _M_swap(_Hash_code_base& __x)
    954       {
    955 	std::swap(_M_extract(), __x._M_extract());
    956 	std::swap(_M_ranged_hash(), __x._M_ranged_hash());
    957       }
    958 
    959       const _ExtractKey&
    960       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
    961 
    962       _ExtractKey&
    963       _M_extract() { return __ebo_extract_key::_S_get(*this); }
    964 
    965       const _Hash&
    966       _M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }
    967 
    968       _Hash&
    969       _M_ranged_hash() { return __ebo_hash::_S_get(*this); }
    970     };
    971 
    972   // No specialization for ranged hash function while caching hash codes.
    973   // That combination is meaningless, and trying to do it is an error.
    974 
    975   /// Specialization: ranged hash function, cache hash codes.  This
    976   /// combination is meaningless, so we provide only a declaration
    977   /// and no definition.
    978   template<typename _Key, typename _Value, typename _ExtractKey,
    979 	   typename _H1, typename _H2, typename _Hash>
    980     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
    981 
    982   /// Specialization: hash function and range-hashing function, no
    983   /// caching of hash codes.
    984   /// Provides typedef and accessor required by C++ 11.
    985   template<typename _Key, typename _Value, typename _ExtractKey,
    986 	   typename _H1, typename _H2>
    987     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
    988 			   _Default_ranged_hash, false>
    989     : private _Hashtable_ebo_helper<0, _ExtractKey>,
    990       private _Hashtable_ebo_helper<1, _H1>,
    991       private _Hashtable_ebo_helper<2, _H2>
    992     {
    993     private:
    994       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
    995       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
    996       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
    997 
    998     public:
    999       typedef _H1 					hasher;
   1000 
   1001       hasher
   1002       hash_function() const
   1003       { return _M_h1(); }
   1004 
   1005     protected:
   1006       typedef std::size_t 				__hash_code;
   1007       typedef _Hash_node<_Value, false>			__node_type;
   1008 
   1009       // We need the default constructor for the local iterators.
   1010       _Hash_code_base() = default;
   1011 
   1012       _Hash_code_base(const _ExtractKey& __ex,
   1013 		      const _H1& __h1, const _H2& __h2,
   1014 		      const _Default_ranged_hash&)
   1015       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
   1016 
   1017       __hash_code
   1018       _M_hash_code(const _Key& __k) const
   1019       { return _M_h1()(__k); }
   1020 
   1021       std::size_t
   1022       _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
   1023       { return _M_h2()(__c, __n); }
   1024 
   1025       std::size_t
   1026       _M_bucket_index(const __node_type* __p,
   1027 		      std::size_t __n) const
   1028       { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v)), __n); }
   1029 
   1030       void
   1031       _M_store_code(__node_type*, __hash_code) const
   1032       { }
   1033 
   1034       void
   1035       _M_copy_code(__node_type*, const __node_type*) const
   1036       { }
   1037 
   1038       void
   1039       _M_swap(_Hash_code_base& __x)
   1040       {
   1041 	std::swap(_M_extract(), __x._M_extract());
   1042 	std::swap(_M_h1(), __x._M_h1());
   1043 	std::swap(_M_h2(), __x._M_h2());
   1044       }
   1045 
   1046       const _ExtractKey&
   1047       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
   1048 
   1049       _ExtractKey&
   1050       _M_extract() { return __ebo_extract_key::_S_get(*this); }
   1051 
   1052       const _H1&
   1053       _M_h1() const { return __ebo_h1::_S_cget(*this); }
   1054 
   1055       _H1&
   1056       _M_h1() { return __ebo_h1::_S_get(*this); }
   1057 
   1058       const _H2&
   1059       _M_h2() const { return __ebo_h2::_S_cget(*this); }
   1060 
   1061       _H2&
   1062       _M_h2() { return __ebo_h2::_S_get(*this); }
   1063     };
   1064 
   1065   /// Specialization: hash function and range-hashing function,
   1066   /// caching hash codes.  H is provided but ignored.  Provides
   1067   /// typedef and accessor required by C++ 11.
   1068   template<typename _Key, typename _Value, typename _ExtractKey,
   1069 	   typename _H1, typename _H2>
   1070     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
   1071 			   _Default_ranged_hash, true>
   1072     : private _Hashtable_ebo_helper<0, _ExtractKey>,
   1073       private _Hashtable_ebo_helper<1, _H1>,
   1074       private _Hashtable_ebo_helper<2, _H2>
   1075     {
   1076     private:
   1077       // Gives access to _M_h2() to the local iterator implementation.
   1078       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
   1079 					 _Default_ranged_hash, true>;
   1080 
   1081       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
   1082       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
   1083       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
   1084 
   1085     public:
   1086       typedef _H1 					hasher;
   1087 
   1088       hasher
   1089       hash_function() const
   1090       { return _M_h1(); }
   1091 
   1092     protected:
   1093       typedef std::size_t 				__hash_code;
   1094       typedef _Hash_node<_Value, true>			__node_type;
   1095 
   1096       _Hash_code_base(const _ExtractKey& __ex,
   1097 		      const _H1& __h1, const _H2& __h2,
   1098 		      const _Default_ranged_hash&)
   1099       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
   1100 
   1101       __hash_code
   1102       _M_hash_code(const _Key& __k) const
   1103       { return _M_h1()(__k); }
   1104 
   1105       std::size_t
   1106       _M_bucket_index(const _Key&, __hash_code __c,
   1107 		      std::size_t __n) const
   1108       { return _M_h2()(__c, __n); }
   1109 
   1110       std::size_t
   1111       _M_bucket_index(const __node_type* __p, std::size_t __n) const
   1112       { return _M_h2()(__p->_M_hash_code, __n); }
   1113 
   1114       void
   1115       _M_store_code(__node_type* __n, __hash_code __c) const
   1116       { __n->_M_hash_code = __c; }
   1117 
   1118       void
   1119       _M_copy_code(__node_type* __to, const __node_type* __from) const
   1120       { __to->_M_hash_code = __from->_M_hash_code; }
   1121 
   1122       void
   1123       _M_swap(_Hash_code_base& __x)
   1124       {
   1125 	std::swap(_M_extract(), __x._M_extract());
   1126 	std::swap(_M_h1(), __x._M_h1());
   1127 	std::swap(_M_h2(), __x._M_h2());
   1128       }
   1129 
   1130       const _ExtractKey&
   1131       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
   1132 
   1133       _ExtractKey&
   1134       _M_extract() { return __ebo_extract_key::_S_get(*this); }
   1135 
   1136       const _H1&
   1137       _M_h1() const { return __ebo_h1::_S_cget(*this); }
   1138 
   1139       _H1&
   1140       _M_h1() { return __ebo_h1::_S_get(*this); }
   1141 
   1142       const _H2&
   1143       _M_h2() const { return __ebo_h2::_S_cget(*this); }
   1144 
   1145       _H2&
   1146       _M_h2() { return __ebo_h2::_S_get(*this); }
   1147     };
   1148 
   1149   /**
   1150    *  Primary class template _Equal_helper.
   1151    *
   1152    */
   1153   template <typename _Key, typename _Value, typename _ExtractKey,
   1154 	    typename _Equal, typename _HashCodeType,
   1155 	    bool __cache_hash_code>
   1156   struct _Equal_helper;
   1157 
   1158   /// Specialization.
   1159   template<typename _Key, typename _Value, typename _ExtractKey,
   1160 	   typename _Equal, typename _HashCodeType>
   1161   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
   1162   {
   1163     static bool
   1164     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
   1165 	      const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
   1166     { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v)); }
   1167   };
   1168 
   1169   /// Specialization.
   1170   template<typename _Key, typename _Value, typename _ExtractKey,
   1171 	   typename _Equal, typename _HashCodeType>
   1172   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
   1173   {
   1174     static bool
   1175     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
   1176 	      const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
   1177     { return __eq(__k, __extract(__n->_M_v)); }
   1178   };
   1179 
   1180 
   1181   /// Specialization.
   1182   template<typename _Key, typename _Value, typename _ExtractKey,
   1183 	   typename _H1, typename _H2, typename _Hash>
   1184     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
   1185 				_H1, _H2, _Hash, true>
   1186     : private _Hashtable_ebo_helper<0, _H2>
   1187     {
   1188     protected:
   1189       using __base_type = _Hashtable_ebo_helper<0, _H2>;
   1190       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
   1191 					       _H1, _H2, _Hash, true>;
   1192 
   1193     public:
   1194       _Local_iterator_base() = default;
   1195       _Local_iterator_base(const __hash_code_base& __base,
   1196 			   _Hash_node<_Value, true>* __p,
   1197 			   std::size_t __bkt, std::size_t __bkt_count)
   1198       : __base_type(__base._M_h2()),
   1199 	_M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
   1200 
   1201       void
   1202       _M_incr()
   1203       {
   1204 	_M_cur = _M_cur->_M_next();
   1205 	if (_M_cur)
   1206 	  {
   1207 	    std::size_t __bkt
   1208 	      = __base_type::_S_get(*this)(_M_cur->_M_hash_code,
   1209 					   _M_bucket_count);
   1210 	    if (__bkt != _M_bucket)
   1211 	      _M_cur = nullptr;
   1212 	  }
   1213       }
   1214 
   1215       _Hash_node<_Value, true>*  _M_cur;
   1216       std::size_t _M_bucket;
   1217       std::size_t _M_bucket_count;
   1218     };
   1219 
   1220   /// Specialization.
   1221   template<typename _Key, typename _Value, typename _ExtractKey,
   1222 	   typename _H1, typename _H2, typename _Hash>
   1223     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
   1224 				_H1, _H2, _Hash, false>
   1225     : private _Hash_code_base<_Key, _Value, _ExtractKey,
   1226 			      _H1, _H2, _Hash, false>
   1227     {
   1228     protected:
   1229       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
   1230 					       _H1, _H2, _Hash, false>;
   1231 
   1232     public:
   1233       _Local_iterator_base() = default;
   1234       _Local_iterator_base(const __hash_code_base& __base,
   1235 			   _Hash_node<_Value, false>* __p,
   1236 			   std::size_t __bkt, std::size_t __bkt_count)
   1237 	: __hash_code_base(__base),
   1238 	  _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
   1239 
   1240       void
   1241       _M_incr()
   1242       {
   1243 	_M_cur = _M_cur->_M_next();
   1244 	if (_M_cur)
   1245 	  {
   1246 	    std::size_t __bkt = this->_M_bucket_index(_M_cur, _M_bucket_count);
   1247 	    if (__bkt != _M_bucket)
   1248 	      _M_cur = nullptr;
   1249 	  }
   1250       }
   1251 
   1252       _Hash_node<_Value, false>*  _M_cur;
   1253       std::size_t _M_bucket;
   1254       std::size_t _M_bucket_count;
   1255     };
   1256 
   1257   template<typename _Key, typename _Value, typename _ExtractKey,
   1258 	   typename _H1, typename _H2, typename _Hash, bool __cache>
   1259     inline bool
   1260     operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
   1261 					  _H1, _H2, _Hash, __cache>& __x,
   1262 	       const _Local_iterator_base<_Key, _Value, _ExtractKey,
   1263 					  _H1, _H2, _Hash, __cache>& __y)
   1264     { return __x._M_cur == __y._M_cur; }
   1265 
   1266   template<typename _Key, typename _Value, typename _ExtractKey,
   1267 	   typename _H1, typename _H2, typename _Hash, bool __cache>
   1268     inline bool
   1269     operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
   1270 					  _H1, _H2, _Hash, __cache>& __x,
   1271 	       const _Local_iterator_base<_Key, _Value, _ExtractKey,
   1272 					  _H1, _H2, _Hash, __cache>& __y)
   1273     { return __x._M_cur != __y._M_cur; }
   1274 
   1275   /// local iterators
   1276   template<typename _Key, typename _Value, typename _ExtractKey,
   1277 	   typename _H1, typename _H2, typename _Hash,
   1278 	   bool __constant_iterators, bool __cache>
   1279     struct _Local_iterator
   1280     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
   1281 				  _H1, _H2, _Hash, __cache>
   1282     {
   1283     private:
   1284       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
   1285 					       _H1, _H2, _Hash, __cache>;
   1286       using __hash_code_base = typename __base_type::__hash_code_base;
   1287     public:
   1288       typedef _Value                                   value_type;
   1289       typedef typename std::conditional<__constant_iterators,
   1290 					const _Value*, _Value*>::type
   1291 						       pointer;
   1292       typedef typename std::conditional<__constant_iterators,
   1293 					const _Value&, _Value&>::type
   1294 						       reference;
   1295       typedef std::ptrdiff_t                           difference_type;
   1296       typedef std::forward_iterator_tag                iterator_category;
   1297 
   1298       _Local_iterator() = default;
   1299 
   1300       _Local_iterator(const __hash_code_base& __base,
   1301 		      _Hash_node<_Value, __cache>* __p,
   1302 		      std::size_t __bkt, std::size_t __bkt_count)
   1303 	: __base_type(__base, __p, __bkt, __bkt_count)
   1304       { }
   1305 
   1306       reference
   1307       operator*() const
   1308       { return this->_M_cur->_M_v; }
   1309 
   1310       pointer
   1311       operator->() const
   1312       { return std::__addressof(this->_M_cur->_M_v); }
   1313 
   1314       _Local_iterator&
   1315       operator++()
   1316       {
   1317 	this->_M_incr();
   1318 	return *this;
   1319       }
   1320 
   1321       _Local_iterator
   1322       operator++(int)
   1323       {
   1324 	_Local_iterator __tmp(*this);
   1325 	this->_M_incr();
   1326 	return __tmp;
   1327       }
   1328     };
   1329 
   1330   /// local const_iterators
   1331   template<typename _Key, typename _Value, typename _ExtractKey,
   1332 	   typename _H1, typename _H2, typename _Hash,
   1333 	   bool __constant_iterators, bool __cache>
   1334     struct _Local_const_iterator
   1335     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
   1336 				  _H1, _H2, _Hash, __cache>
   1337     {
   1338     private:
   1339       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
   1340 					       _H1, _H2, _Hash, __cache>;
   1341       using __hash_code_base = typename __base_type::__hash_code_base;
   1342 
   1343     public:
   1344       typedef _Value                                   value_type;
   1345       typedef const _Value*                            pointer;
   1346       typedef const _Value&                            reference;
   1347       typedef std::ptrdiff_t                           difference_type;
   1348       typedef std::forward_iterator_tag                iterator_category;
   1349 
   1350       _Local_const_iterator() = default;
   1351 
   1352       _Local_const_iterator(const __hash_code_base& __base,
   1353 			    _Hash_node<_Value, __cache>* __p,
   1354 			    std::size_t __bkt, std::size_t __bkt_count)
   1355 	: __base_type(__base, __p, __bkt, __bkt_count)
   1356       { }
   1357 
   1358       _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
   1359 						  _H1, _H2, _Hash,
   1360 						  __constant_iterators,
   1361 						  __cache>& __x)
   1362 	: __base_type(__x)
   1363       { }
   1364 
   1365       reference
   1366       operator*() const
   1367       { return this->_M_cur->_M_v; }
   1368 
   1369       pointer
   1370       operator->() const
   1371       { return std::__addressof(this->_M_cur->_M_v); }
   1372 
   1373       _Local_const_iterator&
   1374       operator++()
   1375       {
   1376 	this->_M_incr();
   1377 	return *this;
   1378       }
   1379 
   1380       _Local_const_iterator
   1381       operator++(int)
   1382       {
   1383 	_Local_const_iterator __tmp(*this);
   1384 	this->_M_incr();
   1385 	return __tmp;
   1386       }
   1387     };
   1388 
   1389   /**
   1390    *  Primary class template _Hashtable_base.
   1391    *
   1392    *  Helper class adding management of _Equal functor to
   1393    *  _Hash_code_base type.
   1394    *
   1395    *  Base class templates are:
   1396    *    - __detail::_Hash_code_base
   1397    *    - __detail::_Hashtable_ebo_helper
   1398    */
   1399   template<typename _Key, typename _Value,
   1400 	   typename _ExtractKey, typename _Equal,
   1401 	   typename _H1, typename _H2, typename _Hash, typename _Traits>
   1402   struct _Hashtable_base
   1403   : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
   1404 			   _Traits::__hash_cached::value>,
   1405     private _Hashtable_ebo_helper<0, _Equal>
   1406   {
   1407   public:
   1408     typedef _Key                                    key_type;
   1409     typedef _Value                                  value_type;
   1410     typedef _Equal                                  key_equal;
   1411     typedef std::size_t                             size_type;
   1412     typedef std::ptrdiff_t                          difference_type;
   1413 
   1414     using __traits_type = _Traits;
   1415     using __hash_cached = typename __traits_type::__hash_cached;
   1416     using __constant_iterators = typename __traits_type::__constant_iterators;
   1417     using __unique_keys = typename __traits_type::__unique_keys;
   1418 
   1419     using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
   1420 					     _H1, _H2, _Hash,
   1421 					     __hash_cached::value>;
   1422 
   1423     using __hash_code = typename __hash_code_base::__hash_code;
   1424     using __node_type = typename __hash_code_base::__node_type;
   1425 
   1426     using iterator = __detail::_Node_iterator<value_type,
   1427 					      __constant_iterators::value,
   1428 					      __hash_cached::value>;
   1429 
   1430     using const_iterator = __detail::_Node_const_iterator<value_type,
   1431 						   __constant_iterators::value,
   1432 						   __hash_cached::value>;
   1433 
   1434     using local_iterator = __detail::_Local_iterator<key_type, value_type,
   1435 						  _ExtractKey, _H1, _H2, _Hash,
   1436 						  __constant_iterators::value,
   1437 						     __hash_cached::value>;
   1438 
   1439     using const_local_iterator = __detail::_Local_const_iterator<key_type,
   1440 								 value_type,
   1441 					_ExtractKey, _H1, _H2, _Hash,
   1442 					__constant_iterators::value,
   1443 					__hash_cached::value>;
   1444 
   1445     using __ireturn_type = typename std::conditional<__unique_keys::value,
   1446 						     std::pair<iterator, bool>,
   1447 						     iterator>::type;
   1448 
   1449     using __iconv_type = typename  std::conditional<__unique_keys::value,
   1450 						    _Select1st, _Identity
   1451 						    >::type;
   1452   private:
   1453     using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
   1454     using _EqualHelper =  _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
   1455 					__hash_code, __hash_cached::value>;
   1456 
   1457   protected:
   1458     using __node_base = __detail::_Hash_node_base;
   1459     using __bucket_type = __node_base*;
   1460 
   1461     _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
   1462 		    const _Hash& __hash, const _Equal& __eq)
   1463     : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
   1464     { }
   1465 
   1466     bool
   1467     _M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
   1468     {
   1469       return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
   1470 				     __k, __c, __n);
   1471     }
   1472 
   1473     void
   1474     _M_swap(_Hashtable_base& __x)
   1475     {
   1476       __hash_code_base::_M_swap(__x);
   1477       std::swap(_M_eq(), __x._M_eq());
   1478     }
   1479 
   1480     const _Equal&
   1481     _M_eq() const { return _EqualEBO::_S_cget(*this); }
   1482 
   1483     _Equal&
   1484     _M_eq() { return _EqualEBO::_S_get(*this); }
   1485   };
   1486 
   1487   /**
   1488    *  struct _Equality_base.
   1489    *
   1490    *  Common types and functions for class _Equality.
   1491    */
   1492   struct _Equality_base
   1493   {
   1494   protected:
   1495     template<typename _Uiterator>
   1496       static bool
   1497       _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
   1498   };
   1499 
   1500   // See std::is_permutation in N3068.
   1501   template<typename _Uiterator>
   1502     bool
   1503     _Equality_base::
   1504     _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
   1505 		      _Uiterator __first2)
   1506     {
   1507       for (; __first1 != __last1; ++__first1, ++__first2)
   1508 	if (!(*__first1 == *__first2))
   1509 	  break;
   1510 
   1511       if (__first1 == __last1)
   1512 	return true;
   1513 
   1514       _Uiterator __last2 = __first2;
   1515       std::advance(__last2, std::distance(__first1, __last1));
   1516 
   1517       for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
   1518 	{
   1519 	  _Uiterator __tmp =  __first1;
   1520 	  while (__tmp != __it1 && !bool(*__tmp == *__it1))
   1521 	    ++__tmp;
   1522 
   1523 	  // We've seen this one before.
   1524 	  if (__tmp != __it1)
   1525 	    continue;
   1526 
   1527 	  std::ptrdiff_t __n2 = 0;
   1528 	  for (__tmp = __first2; __tmp != __last2; ++__tmp)
   1529 	    if (*__tmp == *__it1)
   1530 	      ++__n2;
   1531 
   1532 	  if (!__n2)
   1533 	    return false;
   1534 
   1535 	  std::ptrdiff_t __n1 = 0;
   1536 	  for (__tmp = __it1; __tmp != __last1; ++__tmp)
   1537 	    if (*__tmp == *__it1)
   1538 	      ++__n1;
   1539 
   1540 	  if (__n1 != __n2)
   1541 	    return false;
   1542 	}
   1543       return true;
   1544     }
   1545 
   1546   /**
   1547    *  Primary class template  _Equality.
   1548    *
   1549    *  This is for implementing equality comparison for unordered
   1550    *  containers, per N3068, by John Lakos and Pablo Halpern.
   1551    *  Algorithmically, we follow closely the reference implementations
   1552    *  therein.
   1553    */
   1554   template<typename _Key, typename _Value, typename _Alloc,
   1555 	   typename _ExtractKey, typename _Equal,
   1556 	   typename _H1, typename _H2, typename _Hash,
   1557 	   typename _RehashPolicy, typename _Traits,
   1558 	   bool _Unique_keys = _Traits::__unique_keys::value>
   1559     struct _Equality;
   1560 
   1561   /// Specialization.
   1562   template<typename _Key, typename _Value, typename _Alloc,
   1563 	   typename _ExtractKey, typename _Equal,
   1564 	   typename _H1, typename _H2, typename _Hash,
   1565 	   typename _RehashPolicy, typename _Traits>
   1566     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
   1567 		     _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
   1568     {
   1569       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
   1570 				     _H1, _H2, _Hash, _RehashPolicy, _Traits>;
   1571 
   1572       bool
   1573       _M_equal(const __hashtable&) const;
   1574     };
   1575 
   1576   template<typename _Key, typename _Value, typename _Alloc,
   1577 	   typename _ExtractKey, typename _Equal,
   1578 	   typename _H1, typename _H2, typename _Hash,
   1579 	   typename _RehashPolicy, typename _Traits>
   1580     bool
   1581     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
   1582 	      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
   1583     _M_equal(const __hashtable& __other) const
   1584     {
   1585       const __hashtable* __this = static_cast<const __hashtable*>(this);
   1586 
   1587       if (__this->size() != __other.size())
   1588 	return false;
   1589 
   1590       for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
   1591 	{
   1592 	  const auto __ity = __other.find(_ExtractKey()(*__itx));
   1593 	  if (__ity == __other.end() || !bool(*__ity == *__itx))
   1594 	    return false;
   1595 	}
   1596       return true;
   1597     }
   1598 
   1599   /// Specialization.
   1600   template<typename _Key, typename _Value, typename _Alloc,
   1601 	   typename _ExtractKey, typename _Equal,
   1602 	   typename _H1, typename _H2, typename _Hash,
   1603 	   typename _RehashPolicy, typename _Traits>
   1604     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
   1605 		     _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
   1606     : public _Equality_base
   1607     {
   1608       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
   1609 				     _H1, _H2, _Hash, _RehashPolicy, _Traits>;
   1610 
   1611       bool
   1612       _M_equal(const __hashtable&) const;
   1613     };
   1614 
   1615   template<typename _Key, typename _Value, typename _Alloc,
   1616 	   typename _ExtractKey, typename _Equal,
   1617 	   typename _H1, typename _H2, typename _Hash,
   1618 	   typename _RehashPolicy, typename _Traits>
   1619     bool
   1620     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
   1621 	      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
   1622     _M_equal(const __hashtable& __other) const
   1623     {
   1624       const __hashtable* __this = static_cast<const __hashtable*>(this);
   1625 
   1626       if (__this->size() != __other.size())
   1627 	return false;
   1628 
   1629       for (auto __itx = __this->begin(); __itx != __this->end();)
   1630 	{
   1631 	  const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
   1632 	  const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
   1633 
   1634 	  if (std::distance(__xrange.first, __xrange.second)
   1635 	      != std::distance(__yrange.first, __yrange.second))
   1636 	    return false;
   1637 
   1638 	  if (!_S_is_permutation(__xrange.first, __xrange.second,
   1639 				 __yrange.first))
   1640 	    return false;
   1641 
   1642 	  __itx = __xrange.second;
   1643 	}
   1644       return true;
   1645     }
   1646 
   1647   /**
   1648    * This type is to combine a _Hash_node_base instance with an allocator
   1649    * instance through inheritance to benefit from EBO when possible.
   1650    */
   1651   template<typename _NodeAlloc>
   1652     struct _Before_begin : public _NodeAlloc
   1653     {
   1654       _Hash_node_base _M_node;
   1655 
   1656       _Before_begin(const _Before_begin&) = default;
   1657       _Before_begin(_Before_begin&&) = default;
   1658 
   1659       template<typename _Alloc>
   1660 	_Before_begin(_Alloc&& __a)
   1661 	  : _NodeAlloc(std::forward<_Alloc>(__a))
   1662 	{ }
   1663     };
   1664 
   1665  //@} hashtable-detail
   1666 _GLIBCXX_END_NAMESPACE_VERSION
   1667 } // namespace __detail
   1668 } // namespace std
   1669 
   1670 #endif // _HASHTABLE_POLICY_H
   1671