libstdc++-v3/include/bits/hashtable_policy.h

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