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

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