libstdc++
hashtable_policy.h
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00001 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
00002 
00003 // Copyright (C) 2010-2018 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file bits/hashtable_policy.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly.
00028  *  @headername{unordered_map,unordered_set}
00029  */
00030 
00031 #ifndef _HASHTABLE_POLICY_H
00032 #define _HASHTABLE_POLICY_H 1
00033 
00034 #include <tuple>                // for std::tuple, std::forward_as_tuple
00035 #include <cstdint>              // for std::uint_fast64_t
00036 #include <bits/stl_algobase.h>  // for std::min.
00037 
00038 namespace std _GLIBCXX_VISIBILITY(default)
00039 {
00040 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00041 
00042   template<typename _Key, typename _Value, typename _Alloc,
00043            typename _ExtractKey, typename _Equal,
00044            typename _H1, typename _H2, typename _Hash,
00045            typename _RehashPolicy, typename _Traits>
00046     class _Hashtable;
00047 
00048 namespace __detail
00049 {
00050   /**
00051    *  @defgroup hashtable-detail Base and Implementation Classes
00052    *  @ingroup unordered_associative_containers
00053    *  @{
00054    */
00055   template<typename _Key, typename _Value,
00056            typename _ExtractKey, typename _Equal,
00057            typename _H1, typename _H2, typename _Hash, typename _Traits>
00058     struct _Hashtable_base;
00059 
00060   // Helper function: return distance(first, last) for forward
00061   // iterators, or 0/1 for input iterators.
00062   template<class _Iterator>
00063     inline typename std::iterator_traits<_Iterator>::difference_type
00064     __distance_fw(_Iterator __first, _Iterator __last,
00065                   std::input_iterator_tag)
00066     { return __first != __last ? 1 : 0; }
00067 
00068   template<class _Iterator>
00069     inline typename std::iterator_traits<_Iterator>::difference_type
00070     __distance_fw(_Iterator __first, _Iterator __last,
00071                   std::forward_iterator_tag)
00072     { return std::distance(__first, __last); }
00073 
00074   template<class _Iterator>
00075     inline typename std::iterator_traits<_Iterator>::difference_type
00076     __distance_fw(_Iterator __first, _Iterator __last)
00077     { return __distance_fw(__first, __last,
00078                            std::__iterator_category(__first)); }
00079 
00080   struct _Identity
00081   {
00082     template<typename _Tp>
00083       _Tp&&
00084       operator()(_Tp&& __x) const
00085       { return std::forward<_Tp>(__x); }
00086   };
00087 
00088   struct _Select1st
00089   {
00090     template<typename _Tp>
00091       auto
00092       operator()(_Tp&& __x) const
00093       -> decltype(std::get<0>(std::forward<_Tp>(__x)))
00094       { return std::get<0>(std::forward<_Tp>(__x)); }
00095   };
00096 
00097   template<typename _NodeAlloc>
00098     struct _Hashtable_alloc;
00099 
00100   // Functor recycling a pool of nodes and using allocation once the pool is
00101   // empty.
00102   template<typename _NodeAlloc>
00103     struct _ReuseOrAllocNode
00104     {
00105     private:
00106       using __node_alloc_type = _NodeAlloc;
00107       using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
00108       using __node_alloc_traits =
00109         typename __hashtable_alloc::__node_alloc_traits;
00110       using __node_type = typename __hashtable_alloc::__node_type;
00111 
00112     public:
00113       _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
00114         : _M_nodes(__nodes), _M_h(__h) { }
00115       _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
00116 
00117       ~_ReuseOrAllocNode()
00118       { _M_h._M_deallocate_nodes(_M_nodes); }
00119 
00120       template<typename _Arg>
00121         __node_type*
00122         operator()(_Arg&& __arg) const
00123         {
00124           if (_M_nodes)
00125             {
00126               __node_type* __node = _M_nodes;
00127               _M_nodes = _M_nodes->_M_next();
00128               __node->_M_nxt = nullptr;
00129               auto& __a = _M_h._M_node_allocator();
00130               __node_alloc_traits::destroy(__a, __node->_M_valptr());
00131               __try
00132                 {
00133                   __node_alloc_traits::construct(__a, __node->_M_valptr(),
00134                                                  std::forward<_Arg>(__arg));
00135                 }
00136               __catch(...)
00137                 {
00138                   __node->~__node_type();
00139                   __node_alloc_traits::deallocate(__a, __node, 1);
00140                   __throw_exception_again;
00141                 }
00142               return __node;
00143             }
00144           return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
00145         }
00146 
00147     private:
00148       mutable __node_type* _M_nodes;
00149       __hashtable_alloc& _M_h;
00150     };
00151 
00152   // Functor similar to the previous one but without any pool of nodes to
00153   // recycle.
00154   template<typename _NodeAlloc>
00155     struct _AllocNode
00156     {
00157     private:
00158       using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
00159       using __node_type = typename __hashtable_alloc::__node_type;
00160 
00161     public:
00162       _AllocNode(__hashtable_alloc& __h)
00163         : _M_h(__h) { }
00164 
00165       template<typename _Arg>
00166         __node_type*
00167         operator()(_Arg&& __arg) const
00168         { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
00169 
00170     private:
00171       __hashtable_alloc& _M_h;
00172     };
00173 
00174   // Auxiliary types used for all instantiations of _Hashtable nodes
00175   // and iterators.
00176 
00177   /**
00178    *  struct _Hashtable_traits
00179    *
00180    *  Important traits for hash tables.
00181    *
00182    *  @tparam _Cache_hash_code  Boolean value. True if the value of
00183    *  the hash function is stored along with the value. This is a
00184    *  time-space tradeoff.  Storing it may improve lookup speed by
00185    *  reducing the number of times we need to call the _Equal
00186    *  function.
00187    *
00188    *  @tparam _Constant_iterators  Boolean value. True if iterator and
00189    *  const_iterator are both constant iterator types. This is true
00190    *  for unordered_set and unordered_multiset, false for
00191    *  unordered_map and unordered_multimap.
00192    *
00193    *  @tparam _Unique_keys  Boolean value. True if the return value
00194    *  of _Hashtable::count(k) is always at most one, false if it may
00195    *  be an arbitrary number. This is true for unordered_set and
00196    *  unordered_map, false for unordered_multiset and
00197    *  unordered_multimap.
00198    */
00199   template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
00200     struct _Hashtable_traits
00201     {
00202       using __hash_cached = __bool_constant<_Cache_hash_code>;
00203       using __constant_iterators = __bool_constant<_Constant_iterators>;
00204       using __unique_keys = __bool_constant<_Unique_keys>;
00205     };
00206 
00207   /**
00208    *  struct _Hash_node_base
00209    *
00210    *  Nodes, used to wrap elements stored in the hash table.  A policy
00211    *  template parameter of class template _Hashtable controls whether
00212    *  nodes also store a hash code. In some cases (e.g. strings) this
00213    *  may be a performance win.
00214    */
00215   struct _Hash_node_base
00216   {
00217     _Hash_node_base* _M_nxt;
00218 
00219     _Hash_node_base() noexcept : _M_nxt() { }
00220 
00221     _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
00222   };
00223 
00224   /**
00225    *  struct _Hash_node_value_base
00226    *
00227    *  Node type with the value to store.
00228    */
00229   template<typename _Value>
00230     struct _Hash_node_value_base : _Hash_node_base
00231     {
00232       typedef _Value value_type;
00233 
00234       __gnu_cxx::__aligned_buffer<_Value> _M_storage;
00235 
00236       _Value*
00237       _M_valptr() noexcept
00238       { return _M_storage._M_ptr(); }
00239 
00240       const _Value*
00241       _M_valptr() const noexcept
00242       { return _M_storage._M_ptr(); }
00243 
00244       _Value&
00245       _M_v() noexcept
00246       { return *_M_valptr(); }
00247 
00248       const _Value&
00249       _M_v() const noexcept
00250       { return *_M_valptr(); }
00251     };
00252 
00253   /**
00254    *  Primary template struct _Hash_node.
00255    */
00256   template<typename _Value, bool _Cache_hash_code>
00257     struct _Hash_node;
00258 
00259   /**
00260    *  Specialization for nodes with caches, struct _Hash_node.
00261    *
00262    *  Base class is __detail::_Hash_node_value_base.
00263    */
00264   template<typename _Value>
00265     struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value>
00266     {
00267       std::size_t  _M_hash_code;
00268 
00269       _Hash_node*
00270       _M_next() const noexcept
00271       { return static_cast<_Hash_node*>(this->_M_nxt); }
00272     };
00273 
00274   /**
00275    *  Specialization for nodes without caches, struct _Hash_node.
00276    *
00277    *  Base class is __detail::_Hash_node_value_base.
00278    */
00279   template<typename _Value>
00280     struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value>
00281     {
00282       _Hash_node*
00283       _M_next() const noexcept
00284       { return static_cast<_Hash_node*>(this->_M_nxt); }
00285     };
00286 
00287   /// Base class for node iterators.
00288   template<typename _Value, bool _Cache_hash_code>
00289     struct _Node_iterator_base
00290     {
00291       using __node_type = _Hash_node<_Value, _Cache_hash_code>;
00292 
00293       __node_type*  _M_cur;
00294 
00295       _Node_iterator_base(__node_type* __p) noexcept
00296       : _M_cur(__p) { }
00297 
00298       void
00299       _M_incr() noexcept
00300       { _M_cur = _M_cur->_M_next(); }
00301     };
00302 
00303   template<typename _Value, bool _Cache_hash_code>
00304     inline bool
00305     operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
00306                const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
00307     noexcept
00308     { return __x._M_cur == __y._M_cur; }
00309 
00310   template<typename _Value, bool _Cache_hash_code>
00311     inline bool
00312     operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
00313                const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
00314     noexcept
00315     { return __x._M_cur != __y._M_cur; }
00316 
00317   /// Node iterators, used to iterate through all the hashtable.
00318   template<typename _Value, bool __constant_iterators, bool __cache>
00319     struct _Node_iterator
00320     : public _Node_iterator_base<_Value, __cache>
00321     {
00322     private:
00323       using __base_type = _Node_iterator_base<_Value, __cache>;
00324       using __node_type = typename __base_type::__node_type;
00325 
00326     public:
00327       typedef _Value                                    value_type;
00328       typedef std::ptrdiff_t                            difference_type;
00329       typedef std::forward_iterator_tag                 iterator_category;
00330 
00331       using pointer = typename std::conditional<__constant_iterators,
00332                                                 const _Value*, _Value*>::type;
00333 
00334       using reference = typename std::conditional<__constant_iterators,
00335                                                   const _Value&, _Value&>::type;
00336 
00337       _Node_iterator() noexcept
00338       : __base_type(0) { }
00339 
00340       explicit
00341       _Node_iterator(__node_type* __p) noexcept
00342       : __base_type(__p) { }
00343 
00344       reference
00345       operator*() const noexcept
00346       { return this->_M_cur->_M_v(); }
00347 
00348       pointer
00349       operator->() const noexcept
00350       { return this->_M_cur->_M_valptr(); }
00351 
00352       _Node_iterator&
00353       operator++() noexcept
00354       {
00355         this->_M_incr();
00356         return *this;
00357       }
00358 
00359       _Node_iterator
00360       operator++(int) noexcept
00361       {
00362         _Node_iterator __tmp(*this);
00363         this->_M_incr();
00364         return __tmp;
00365       }
00366     };
00367 
00368   /// Node const_iterators, used to iterate through all the hashtable.
00369   template<typename _Value, bool __constant_iterators, bool __cache>
00370     struct _Node_const_iterator
00371     : public _Node_iterator_base<_Value, __cache>
00372     {
00373     private:
00374       using __base_type = _Node_iterator_base<_Value, __cache>;
00375       using __node_type = typename __base_type::__node_type;
00376 
00377     public:
00378       typedef _Value                                    value_type;
00379       typedef std::ptrdiff_t                            difference_type;
00380       typedef std::forward_iterator_tag                 iterator_category;
00381 
00382       typedef const _Value*                             pointer;
00383       typedef const _Value&                             reference;
00384 
00385       _Node_const_iterator() noexcept
00386       : __base_type(0) { }
00387 
00388       explicit
00389       _Node_const_iterator(__node_type* __p) noexcept
00390       : __base_type(__p) { }
00391 
00392       _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
00393                            __cache>& __x) noexcept
00394       : __base_type(__x._M_cur) { }
00395 
00396       reference
00397       operator*() const noexcept
00398       { return this->_M_cur->_M_v(); }
00399 
00400       pointer
00401       operator->() const noexcept
00402       { return this->_M_cur->_M_valptr(); }
00403 
00404       _Node_const_iterator&
00405       operator++() noexcept
00406       {
00407         this->_M_incr();
00408         return *this;
00409       }
00410 
00411       _Node_const_iterator
00412       operator++(int) noexcept
00413       {
00414         _Node_const_iterator __tmp(*this);
00415         this->_M_incr();
00416         return __tmp;
00417       }
00418     };
00419 
00420   // Many of class template _Hashtable's template parameters are policy
00421   // classes.  These are defaults for the policies.
00422 
00423   /// Default range hashing function: use division to fold a large number
00424   /// into the range [0, N).
00425   struct _Mod_range_hashing
00426   {
00427     typedef std::size_t first_argument_type;
00428     typedef std::size_t second_argument_type;
00429     typedef std::size_t result_type;
00430 
00431     result_type
00432     operator()(first_argument_type __num,
00433                second_argument_type __den) const noexcept
00434     { return __num % __den; }
00435   };
00436 
00437   /// Default ranged hash function H.  In principle it should be a
00438   /// function object composed from objects of type H1 and H2 such that
00439   /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
00440   /// h1 and h2.  So instead we'll just use a tag to tell class template
00441   /// hashtable to do that composition.
00442   struct _Default_ranged_hash { };
00443 
00444   /// Default value for rehash policy.  Bucket size is (usually) the
00445   /// smallest prime that keeps the load factor small enough.
00446   struct _Prime_rehash_policy
00447   {
00448     using __has_load_factor = std::true_type;
00449 
00450     _Prime_rehash_policy(float __z = 1.0) noexcept
00451     : _M_max_load_factor(__z), _M_next_resize(0) { }
00452 
00453     float
00454     max_load_factor() const noexcept
00455     { return _M_max_load_factor; }
00456 
00457     // Return a bucket size no smaller than n.
00458     std::size_t
00459     _M_next_bkt(std::size_t __n) const;
00460 
00461     // Return a bucket count appropriate for n elements
00462     std::size_t
00463     _M_bkt_for_elements(std::size_t __n) const
00464     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
00465 
00466     // __n_bkt is current bucket count, __n_elt is current element count,
00467     // and __n_ins is number of elements to be inserted.  Do we need to
00468     // increase bucket count?  If so, return make_pair(true, n), where n
00469     // is the new bucket count.  If not, return make_pair(false, 0).
00470     std::pair<bool, std::size_t>
00471     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
00472                    std::size_t __n_ins) const;
00473 
00474     typedef std::size_t _State;
00475 
00476     _State
00477     _M_state() const
00478     { return _M_next_resize; }
00479 
00480     void
00481     _M_reset() noexcept
00482     { _M_next_resize = 0; }
00483 
00484     void
00485     _M_reset(_State __state)
00486     { _M_next_resize = __state; }
00487 
00488     static const std::size_t _S_growth_factor = 2;
00489 
00490     float               _M_max_load_factor;
00491     mutable std::size_t _M_next_resize;
00492   };
00493 
00494   /// Range hashing function assuming that second arg is a power of 2.
00495   struct _Mask_range_hashing
00496   {
00497     typedef std::size_t first_argument_type;
00498     typedef std::size_t second_argument_type;
00499     typedef std::size_t result_type;
00500 
00501     result_type
00502     operator()(first_argument_type __num,
00503                second_argument_type __den) const noexcept
00504     { return __num & (__den - 1); }
00505   };
00506 
00507   /// Compute closest power of 2.
00508   _GLIBCXX14_CONSTEXPR
00509   inline std::size_t
00510   __clp2(std::size_t __n) noexcept
00511   {
00512 #if __SIZEOF_SIZE_T__ >= 8
00513     std::uint_fast64_t __x = __n;
00514 #else
00515     std::uint_fast32_t __x = __n;
00516 #endif
00517     // Algorithm from Hacker's Delight, Figure 3-3.
00518     __x = __x - 1;
00519     __x = __x | (__x >> 1);
00520     __x = __x | (__x >> 2);
00521     __x = __x | (__x >> 4);
00522     __x = __x | (__x >> 8);
00523     __x = __x | (__x >>16);
00524 #if __SIZEOF_SIZE_T__ >= 8
00525     __x = __x | (__x >>32);
00526 #endif
00527     return __x + 1;
00528   }
00529 
00530   /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
00531   /// operations.
00532   struct _Power2_rehash_policy
00533   {
00534     using __has_load_factor = std::true_type;
00535 
00536     _Power2_rehash_policy(float __z = 1.0) noexcept
00537     : _M_max_load_factor(__z), _M_next_resize(0) { }
00538 
00539     float
00540     max_load_factor() const noexcept
00541     { return _M_max_load_factor; }
00542 
00543     // Return a bucket size no smaller than n (as long as n is not above the
00544     // highest power of 2).
00545     std::size_t
00546     _M_next_bkt(std::size_t __n) noexcept
00547     {
00548       const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
00549       const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
00550       std::size_t __res = __clp2(__n);
00551 
00552       if (__res == __n)
00553         __res <<= 1;
00554 
00555       if (__res == 0)
00556         __res = __max_bkt;
00557 
00558       if (__res == __max_bkt)
00559         // Set next resize to the max value so that we never try to rehash again
00560         // as we already reach the biggest possible bucket number.
00561         // Note that it might result in max_load_factor not being respected.
00562         _M_next_resize = std::size_t(-1);
00563       else
00564         _M_next_resize
00565           = __builtin_ceil(__res * (long double)_M_max_load_factor);
00566 
00567       return __res;
00568     }
00569 
00570     // Return a bucket count appropriate for n elements
00571     std::size_t
00572     _M_bkt_for_elements(std::size_t __n) const noexcept
00573     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
00574 
00575     // __n_bkt is current bucket count, __n_elt is current element count,
00576     // and __n_ins is number of elements to be inserted.  Do we need to
00577     // increase bucket count?  If so, return make_pair(true, n), where n
00578     // is the new bucket count.  If not, return make_pair(false, 0).
00579     std::pair<bool, std::size_t>
00580     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
00581                    std::size_t __n_ins) noexcept
00582     {
00583       if (__n_elt + __n_ins >= _M_next_resize)
00584         {
00585           long double __min_bkts = (__n_elt + __n_ins)
00586                                         / (long double)_M_max_load_factor;
00587           if (__min_bkts >= __n_bkt)
00588             return std::make_pair(true,
00589               _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
00590                                                 __n_bkt * _S_growth_factor)));
00591 
00592           _M_next_resize
00593             = __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
00594           return std::make_pair(false, 0);
00595         }
00596       else
00597         return std::make_pair(false, 0);
00598     }
00599 
00600     typedef std::size_t _State;
00601 
00602     _State
00603     _M_state() const noexcept
00604     { return _M_next_resize; }
00605 
00606     void
00607     _M_reset() noexcept
00608     { _M_next_resize = 0; }
00609 
00610     void
00611     _M_reset(_State __state) noexcept
00612     { _M_next_resize = __state; }
00613 
00614     static const std::size_t _S_growth_factor = 2;
00615 
00616     float       _M_max_load_factor;
00617     std::size_t _M_next_resize;
00618   };
00619 
00620   // Base classes for std::_Hashtable.  We define these base classes
00621   // because in some cases we want to do different things depending on
00622   // the value of a policy class.  In some cases the policy class
00623   // affects which member functions and nested typedefs are defined;
00624   // we handle that by specializing base class templates.  Several of
00625   // the base class templates need to access other members of class
00626   // template _Hashtable, so we use a variant of the "Curiously
00627   // Recurring Template Pattern" (CRTP) technique.
00628 
00629   /**
00630    *  Primary class template _Map_base.
00631    *
00632    *  If the hashtable has a value type of the form pair<T1, T2> and a
00633    *  key extraction policy (_ExtractKey) that returns the first part
00634    *  of the pair, the hashtable gets a mapped_type typedef.  If it
00635    *  satisfies those criteria and also has unique keys, then it also
00636    *  gets an operator[].
00637    */
00638   template<typename _Key, typename _Value, typename _Alloc,
00639            typename _ExtractKey, typename _Equal,
00640            typename _H1, typename _H2, typename _Hash,
00641            typename _RehashPolicy, typename _Traits,
00642            bool _Unique_keys = _Traits::__unique_keys::value>
00643     struct _Map_base { };
00644 
00645   /// Partial specialization, __unique_keys set to false.
00646   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00647            typename _H1, typename _H2, typename _Hash,
00648            typename _RehashPolicy, typename _Traits>
00649     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00650                      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
00651     {
00652       using mapped_type = typename std::tuple_element<1, _Pair>::type;
00653     };
00654 
00655   /// Partial specialization, __unique_keys set to true.
00656   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00657            typename _H1, typename _H2, typename _Hash,
00658            typename _RehashPolicy, typename _Traits>
00659     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00660                      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
00661     {
00662     private:
00663       using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
00664                                                          _Select1st,
00665                                                         _Equal, _H1, _H2, _Hash,
00666                                                           _Traits>;
00667 
00668       using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
00669                                      _Select1st, _Equal,
00670                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
00671 
00672       using __hash_code = typename __hashtable_base::__hash_code;
00673       using __node_type = typename __hashtable_base::__node_type;
00674 
00675     public:
00676       using key_type = typename __hashtable_base::key_type;
00677       using iterator = typename __hashtable_base::iterator;
00678       using mapped_type = typename std::tuple_element<1, _Pair>::type;
00679 
00680       mapped_type&
00681       operator[](const key_type& __k);
00682 
00683       mapped_type&
00684       operator[](key_type&& __k);
00685 
00686       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00687       // DR 761. unordered_map needs an at() member function.
00688       mapped_type&
00689       at(const key_type& __k);
00690 
00691       const mapped_type&
00692       at(const key_type& __k) const;
00693     };
00694 
00695   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00696            typename _H1, typename _H2, typename _Hash,
00697            typename _RehashPolicy, typename _Traits>
00698     auto
00699     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00700               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00701     operator[](const key_type& __k)
00702     -> mapped_type&
00703     {
00704       __hashtable* __h = static_cast<__hashtable*>(this);
00705       __hash_code __code = __h->_M_hash_code(__k);
00706       std::size_t __n = __h->_M_bucket_index(__k, __code);
00707       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00708 
00709       if (!__p)
00710         {
00711           __p = __h->_M_allocate_node(std::piecewise_construct,
00712                                       std::tuple<const key_type&>(__k),
00713                                       std::tuple<>());
00714           return __h->_M_insert_unique_node(__n, __code, __p)->second;
00715         }
00716 
00717       return __p->_M_v().second;
00718     }
00719 
00720   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00721            typename _H1, typename _H2, typename _Hash,
00722            typename _RehashPolicy, typename _Traits>
00723     auto
00724     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00725               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00726     operator[](key_type&& __k)
00727     -> mapped_type&
00728     {
00729       __hashtable* __h = static_cast<__hashtable*>(this);
00730       __hash_code __code = __h->_M_hash_code(__k);
00731       std::size_t __n = __h->_M_bucket_index(__k, __code);
00732       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00733 
00734       if (!__p)
00735         {
00736           __p = __h->_M_allocate_node(std::piecewise_construct,
00737                                       std::forward_as_tuple(std::move(__k)),
00738                                       std::tuple<>());
00739           return __h->_M_insert_unique_node(__n, __code, __p)->second;
00740         }
00741 
00742       return __p->_M_v().second;
00743     }
00744 
00745   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00746            typename _H1, typename _H2, typename _Hash,
00747            typename _RehashPolicy, typename _Traits>
00748     auto
00749     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00750               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00751     at(const key_type& __k)
00752     -> mapped_type&
00753     {
00754       __hashtable* __h = static_cast<__hashtable*>(this);
00755       __hash_code __code = __h->_M_hash_code(__k);
00756       std::size_t __n = __h->_M_bucket_index(__k, __code);
00757       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00758 
00759       if (!__p)
00760         __throw_out_of_range(__N("_Map_base::at"));
00761       return __p->_M_v().second;
00762     }
00763 
00764   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00765            typename _H1, typename _H2, typename _Hash,
00766            typename _RehashPolicy, typename _Traits>
00767     auto
00768     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00769               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00770     at(const key_type& __k) const
00771     -> const mapped_type&
00772     {
00773       const __hashtable* __h = static_cast<const __hashtable*>(this);
00774       __hash_code __code = __h->_M_hash_code(__k);
00775       std::size_t __n = __h->_M_bucket_index(__k, __code);
00776       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00777 
00778       if (!__p)
00779         __throw_out_of_range(__N("_Map_base::at"));
00780       return __p->_M_v().second;
00781     }
00782 
00783   /**
00784    *  Primary class template _Insert_base.
00785    *
00786    *  Defines @c insert member functions appropriate to all _Hashtables.
00787    */
00788   template<typename _Key, typename _Value, typename _Alloc,
00789            typename _ExtractKey, typename _Equal,
00790            typename _H1, typename _H2, typename _Hash,
00791            typename _RehashPolicy, typename _Traits>
00792     struct _Insert_base
00793     {
00794     protected:
00795       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
00796                                      _Equal, _H1, _H2, _Hash,
00797                                      _RehashPolicy, _Traits>;
00798 
00799       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
00800                                                _Equal, _H1, _H2, _Hash,
00801                                                _Traits>;
00802 
00803       using value_type = typename __hashtable_base::value_type;
00804       using iterator = typename __hashtable_base::iterator;
00805       using const_iterator =  typename __hashtable_base::const_iterator;
00806       using size_type = typename __hashtable_base::size_type;
00807 
00808       using __unique_keys = typename __hashtable_base::__unique_keys;
00809       using __ireturn_type = typename __hashtable_base::__ireturn_type;
00810       using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>;
00811       using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
00812       using __node_gen_type = _AllocNode<__node_alloc_type>;
00813 
00814       __hashtable&
00815       _M_conjure_hashtable()
00816       { return *(static_cast<__hashtable*>(this)); }
00817 
00818       template<typename _InputIterator, typename _NodeGetter>
00819         void
00820         _M_insert_range(_InputIterator __first, _InputIterator __last,
00821                         const _NodeGetter&, true_type);
00822 
00823       template<typename _InputIterator, typename _NodeGetter>
00824         void
00825         _M_insert_range(_InputIterator __first, _InputIterator __last,
00826                         const _NodeGetter&, false_type);
00827 
00828     public:
00829       __ireturn_type
00830       insert(const value_type& __v)
00831       {
00832         __hashtable& __h = _M_conjure_hashtable();
00833         __node_gen_type __node_gen(__h);
00834         return __h._M_insert(__v, __node_gen, __unique_keys());
00835       }
00836 
00837       iterator
00838       insert(const_iterator __hint, const value_type& __v)
00839       {
00840         __hashtable& __h = _M_conjure_hashtable();
00841         __node_gen_type __node_gen(__h);        
00842         return __h._M_insert(__hint, __v, __node_gen, __unique_keys());
00843       }
00844 
00845       void
00846       insert(initializer_list<value_type> __l)
00847       { this->insert(__l.begin(), __l.end()); }
00848 
00849       template<typename _InputIterator>
00850         void
00851         insert(_InputIterator __first, _InputIterator __last)
00852         {
00853           __hashtable& __h = _M_conjure_hashtable();
00854           __node_gen_type __node_gen(__h);
00855           return _M_insert_range(__first, __last, __node_gen, __unique_keys());
00856         }
00857     };
00858 
00859   template<typename _Key, typename _Value, typename _Alloc,
00860            typename _ExtractKey, typename _Equal,
00861            typename _H1, typename _H2, typename _Hash,
00862            typename _RehashPolicy, typename _Traits>
00863     template<typename _InputIterator, typename _NodeGetter>
00864       void
00865       _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00866                     _RehashPolicy, _Traits>::
00867       _M_insert_range(_InputIterator __first, _InputIterator __last,
00868                       const _NodeGetter& __node_gen, true_type)
00869       {
00870         size_type __n_elt = __detail::__distance_fw(__first, __last);
00871         if (__n_elt == 0)
00872           return;
00873 
00874         __hashtable& __h = _M_conjure_hashtable();
00875         for (; __first != __last; ++__first)
00876           {
00877             if (__h._M_insert(*__first, __node_gen, __unique_keys(),
00878                               __n_elt).second)
00879               __n_elt = 1;
00880             else if (__n_elt != 1)
00881               --__n_elt;
00882           }
00883       }
00884 
00885   template<typename _Key, typename _Value, typename _Alloc,
00886            typename _ExtractKey, typename _Equal,
00887            typename _H1, typename _H2, typename _Hash,
00888            typename _RehashPolicy, typename _Traits>
00889     template<typename _InputIterator, typename _NodeGetter>
00890       void
00891       _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00892                     _RehashPolicy, _Traits>::
00893       _M_insert_range(_InputIterator __first, _InputIterator __last,
00894                       const _NodeGetter& __node_gen, false_type)
00895       {
00896         using __rehash_type = typename __hashtable::__rehash_type;
00897         using __rehash_state = typename __hashtable::__rehash_state;
00898         using pair_type = std::pair<bool, std::size_t>;
00899 
00900         size_type __n_elt = __detail::__distance_fw(__first, __last);
00901         if (__n_elt == 0)
00902           return;
00903 
00904         __hashtable& __h = _M_conjure_hashtable();
00905         __rehash_type& __rehash = __h._M_rehash_policy;
00906         const __rehash_state& __saved_state = __rehash._M_state();
00907         pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
00908                                                         __h._M_element_count,
00909                                                         __n_elt);
00910 
00911         if (__do_rehash.first)
00912           __h._M_rehash(__do_rehash.second, __saved_state);
00913 
00914         for (; __first != __last; ++__first)
00915           __h._M_insert(*__first, __node_gen, __unique_keys());
00916       }
00917 
00918   /**
00919    *  Primary class template _Insert.
00920    *
00921    *  Defines @c insert member functions that depend on _Hashtable policies,
00922    *  via partial specializations.
00923    */
00924   template<typename _Key, typename _Value, typename _Alloc,
00925            typename _ExtractKey, typename _Equal,
00926            typename _H1, typename _H2, typename _Hash,
00927            typename _RehashPolicy, typename _Traits,
00928            bool _Constant_iterators = _Traits::__constant_iterators::value>
00929     struct _Insert;
00930 
00931   /// Specialization.
00932   template<typename _Key, typename _Value, typename _Alloc,
00933            typename _ExtractKey, typename _Equal,
00934            typename _H1, typename _H2, typename _Hash,
00935            typename _RehashPolicy, typename _Traits>
00936     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00937                    _RehashPolicy, _Traits, true>
00938     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00939                            _H1, _H2, _Hash, _RehashPolicy, _Traits>
00940     {
00941       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
00942                                         _Equal, _H1, _H2, _Hash,
00943                                         _RehashPolicy, _Traits>;
00944 
00945       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
00946                                                _Equal, _H1, _H2, _Hash,
00947                                                _Traits>;
00948 
00949       using value_type = typename __base_type::value_type;
00950       using iterator = typename __base_type::iterator;
00951       using const_iterator =  typename __base_type::const_iterator;
00952 
00953       using __unique_keys = typename __base_type::__unique_keys;
00954       using __ireturn_type = typename __hashtable_base::__ireturn_type;
00955       using __hashtable = typename __base_type::__hashtable;
00956       using __node_gen_type = typename __base_type::__node_gen_type;
00957 
00958       using __base_type::insert;
00959 
00960       __ireturn_type
00961       insert(value_type&& __v)
00962       {
00963         __hashtable& __h = this->_M_conjure_hashtable();
00964         __node_gen_type __node_gen(__h);
00965         return __h._M_insert(std::move(__v), __node_gen, __unique_keys());
00966       }
00967 
00968       iterator
00969       insert(const_iterator __hint, value_type&& __v)
00970       {
00971         __hashtable& __h = this->_M_conjure_hashtable();
00972         __node_gen_type __node_gen(__h);
00973         return __h._M_insert(__hint, std::move(__v), __node_gen,
00974                              __unique_keys());
00975       }
00976     };
00977 
00978   /// Specialization.
00979   template<typename _Key, typename _Value, typename _Alloc,
00980            typename _ExtractKey, typename _Equal,
00981            typename _H1, typename _H2, typename _Hash,
00982            typename _RehashPolicy, typename _Traits>
00983     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00984                    _RehashPolicy, _Traits, false>
00985     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00986                            _H1, _H2, _Hash, _RehashPolicy, _Traits>
00987     {
00988       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
00989                                        _Equal, _H1, _H2, _Hash,
00990                                        _RehashPolicy, _Traits>;
00991       using value_type = typename __base_type::value_type;
00992       using iterator = typename __base_type::iterator;
00993       using const_iterator =  typename __base_type::const_iterator;
00994 
00995       using __unique_keys = typename __base_type::__unique_keys;
00996       using __hashtable = typename __base_type::__hashtable;
00997       using __ireturn_type = typename __base_type::__ireturn_type;
00998 
00999       using __base_type::insert;
01000 
01001       template<typename _Pair>
01002         using __is_cons = std::is_constructible<value_type, _Pair&&>;
01003 
01004       template<typename _Pair>
01005         using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
01006 
01007       template<typename _Pair>
01008         using _IFconsp = typename _IFcons<_Pair>::type;
01009 
01010       template<typename _Pair, typename = _IFconsp<_Pair>>
01011         __ireturn_type
01012         insert(_Pair&& __v)
01013         {
01014           __hashtable& __h = this->_M_conjure_hashtable();
01015           return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
01016         }
01017 
01018       template<typename _Pair, typename = _IFconsp<_Pair>>
01019         iterator
01020         insert(const_iterator __hint, _Pair&& __v)
01021         {
01022           __hashtable& __h = this->_M_conjure_hashtable();
01023           return __h._M_emplace(__hint, __unique_keys(),
01024                                 std::forward<_Pair>(__v));
01025         }
01026    };
01027 
01028   template<typename _Policy>
01029     using __has_load_factor = typename _Policy::__has_load_factor;
01030 
01031   /**
01032    *  Primary class template  _Rehash_base.
01033    *
01034    *  Give hashtable the max_load_factor functions and reserve iff the
01035    *  rehash policy supports it.
01036   */
01037   template<typename _Key, typename _Value, typename _Alloc,
01038            typename _ExtractKey, typename _Equal,
01039            typename _H1, typename _H2, typename _Hash,
01040            typename _RehashPolicy, typename _Traits,
01041            typename =
01042              __detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>>
01043     struct _Rehash_base;
01044 
01045   /// Specialization when rehash policy doesn't provide load factor management.
01046   template<typename _Key, typename _Value, typename _Alloc,
01047            typename _ExtractKey, typename _Equal,
01048            typename _H1, typename _H2, typename _Hash,
01049            typename _RehashPolicy, typename _Traits>
01050     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01051                       _H1, _H2, _Hash, _RehashPolicy, _Traits,
01052                       std::false_type>
01053     {
01054     };
01055 
01056   /// Specialization when rehash policy provide load factor management.
01057   template<typename _Key, typename _Value, typename _Alloc,
01058            typename _ExtractKey, typename _Equal,
01059            typename _H1, typename _H2, typename _Hash,
01060            typename _RehashPolicy, typename _Traits>
01061     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01062                         _H1, _H2, _Hash, _RehashPolicy, _Traits,
01063                         std::true_type>
01064     {
01065       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
01066                                      _Equal, _H1, _H2, _Hash,
01067                                      _RehashPolicy, _Traits>;
01068 
01069       float
01070       max_load_factor() const noexcept
01071       {
01072         const __hashtable* __this = static_cast<const __hashtable*>(this);
01073         return __this->__rehash_policy().max_load_factor();
01074       }
01075 
01076       void
01077       max_load_factor(float __z)
01078       {
01079         __hashtable* __this = static_cast<__hashtable*>(this);
01080         __this->__rehash_policy(_RehashPolicy(__z));
01081       }
01082 
01083       void
01084       reserve(std::size_t __n)
01085       {
01086         __hashtable* __this = static_cast<__hashtable*>(this);
01087         __this->rehash(__builtin_ceil(__n / max_load_factor()));
01088       }
01089     };
01090 
01091   /**
01092    *  Primary class template _Hashtable_ebo_helper.
01093    *
01094    *  Helper class using EBO when it is not forbidden (the type is not
01095    *  final) and when it is worth it (the type is empty.)
01096    */
01097   template<int _Nm, typename _Tp,
01098            bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
01099     struct _Hashtable_ebo_helper;
01100 
01101   /// Specialization using EBO.
01102   template<int _Nm, typename _Tp>
01103     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
01104     : private _Tp
01105     {
01106       _Hashtable_ebo_helper() = default;
01107 
01108       template<typename _OtherTp>
01109         _Hashtable_ebo_helper(_OtherTp&& __tp)
01110           : _Tp(std::forward<_OtherTp>(__tp))
01111         { }
01112 
01113       static const _Tp&
01114       _S_cget(const _Hashtable_ebo_helper& __eboh)
01115       { return static_cast<const _Tp&>(__eboh); }
01116 
01117       static _Tp&
01118       _S_get(_Hashtable_ebo_helper& __eboh)
01119       { return static_cast<_Tp&>(__eboh); }
01120     };
01121 
01122   /// Specialization not using EBO.
01123   template<int _Nm, typename _Tp>
01124     struct _Hashtable_ebo_helper<_Nm, _Tp, false>
01125     {
01126       _Hashtable_ebo_helper() = default;
01127 
01128       template<typename _OtherTp>
01129         _Hashtable_ebo_helper(_OtherTp&& __tp)
01130           : _M_tp(std::forward<_OtherTp>(__tp))
01131         { }
01132 
01133       static const _Tp&
01134       _S_cget(const _Hashtable_ebo_helper& __eboh)
01135       { return __eboh._M_tp; }
01136 
01137       static _Tp&
01138       _S_get(_Hashtable_ebo_helper& __eboh)
01139       { return __eboh._M_tp; }
01140 
01141     private:
01142       _Tp _M_tp;
01143     };
01144 
01145   /**
01146    *  Primary class template _Local_iterator_base.
01147    *
01148    *  Base class for local iterators, used to iterate within a bucket
01149    *  but not between buckets.
01150    */
01151   template<typename _Key, typename _Value, typename _ExtractKey,
01152            typename _H1, typename _H2, typename _Hash,
01153            bool __cache_hash_code>
01154     struct _Local_iterator_base;
01155 
01156   /**
01157    *  Primary class template _Hash_code_base.
01158    *
01159    *  Encapsulates two policy issues that aren't quite orthogonal.
01160    *   (1) the difference between using a ranged hash function and using
01161    *       the combination of a hash function and a range-hashing function.
01162    *       In the former case we don't have such things as hash codes, so
01163    *       we have a dummy type as placeholder.
01164    *   (2) Whether or not we cache hash codes.  Caching hash codes is
01165    *       meaningless if we have a ranged hash function.
01166    *
01167    *  We also put the key extraction objects here, for convenience.
01168    *  Each specialization derives from one or more of the template
01169    *  parameters to benefit from Ebo. This is important as this type
01170    *  is inherited in some cases by the _Local_iterator_base type used
01171    *  to implement local_iterator and const_local_iterator. As with
01172    *  any iterator type we prefer to make it as small as possible.
01173    *
01174    *  Primary template is unused except as a hook for specializations.
01175    */
01176   template<typename _Key, typename _Value, typename _ExtractKey,
01177            typename _H1, typename _H2, typename _Hash,
01178            bool __cache_hash_code>
01179     struct _Hash_code_base;
01180 
01181   /// Specialization: ranged hash function, no caching hash codes.  H1
01182   /// and H2 are provided but ignored.  We define a dummy hash code type.
01183   template<typename _Key, typename _Value, typename _ExtractKey,
01184            typename _H1, typename _H2, typename _Hash>
01185     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
01186     : private _Hashtable_ebo_helper<0, _ExtractKey>,
01187       private _Hashtable_ebo_helper<1, _Hash>
01188     {
01189     private:
01190       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
01191       using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
01192 
01193     protected:
01194       typedef void*                                     __hash_code;
01195       typedef _Hash_node<_Value, false>                 __node_type;
01196 
01197       // We need the default constructor for the local iterators and _Hashtable
01198       // default constructor.
01199       _Hash_code_base() = default;
01200 
01201       _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
01202                       const _Hash& __h)
01203       : __ebo_extract_key(__ex), __ebo_hash(__h) { }
01204 
01205       __hash_code
01206       _M_hash_code(const _Key& __key) const
01207       { return 0; }
01208 
01209       std::size_t
01210       _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
01211       { return _M_ranged_hash()(__k, __n); }
01212 
01213       std::size_t
01214       _M_bucket_index(const __node_type* __p, std::size_t __n) const
01215         noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(),
01216                                                    (std::size_t)0)) )
01217       { return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); }
01218 
01219       void
01220       _M_store_code(__node_type*, __hash_code) const
01221       { }
01222 
01223       void
01224       _M_copy_code(__node_type*, const __node_type*) const
01225       { }
01226 
01227       void
01228       _M_swap(_Hash_code_base& __x)
01229       {
01230         std::swap(_M_extract(), __x._M_extract());
01231         std::swap(_M_ranged_hash(), __x._M_ranged_hash());
01232       }
01233 
01234       const _ExtractKey&
01235       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
01236 
01237       _ExtractKey&
01238       _M_extract() { return __ebo_extract_key::_S_get(*this); }
01239 
01240       const _Hash&
01241       _M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }
01242 
01243       _Hash&
01244       _M_ranged_hash() { return __ebo_hash::_S_get(*this); }
01245     };
01246 
01247   // No specialization for ranged hash function while caching hash codes.
01248   // That combination is meaningless, and trying to do it is an error.
01249 
01250   /// Specialization: ranged hash function, cache hash codes.  This
01251   /// combination is meaningless, so we provide only a declaration
01252   /// and no definition.
01253   template<typename _Key, typename _Value, typename _ExtractKey,
01254            typename _H1, typename _H2, typename _Hash>
01255     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
01256 
01257   /// Specialization: hash function and range-hashing function, no
01258   /// caching of hash codes.
01259   /// Provides typedef and accessor required by C++ 11.
01260   template<typename _Key, typename _Value, typename _ExtractKey,
01261            typename _H1, typename _H2>
01262     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
01263                            _Default_ranged_hash, false>
01264     : private _Hashtable_ebo_helper<0, _ExtractKey>,
01265       private _Hashtable_ebo_helper<1, _H1>,
01266       private _Hashtable_ebo_helper<2, _H2>
01267     {
01268     private:
01269       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
01270       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
01271       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
01272 
01273       // Gives the local iterator implementation access to _M_bucket_index().
01274       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
01275                                          _Default_ranged_hash, false>;
01276 
01277     public:
01278       typedef _H1                                       hasher;
01279 
01280       hasher
01281       hash_function() const
01282       { return _M_h1(); }
01283 
01284     protected:
01285       typedef std::size_t                               __hash_code;
01286       typedef _Hash_node<_Value, false>                 __node_type;
01287 
01288       // We need the default constructor for the local iterators and _Hashtable
01289       // default constructor.
01290       _Hash_code_base() = default;
01291 
01292       _Hash_code_base(const _ExtractKey& __ex,
01293                       const _H1& __h1, const _H2& __h2,
01294                       const _Default_ranged_hash&)
01295       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
01296 
01297       __hash_code
01298       _M_hash_code(const _Key& __k) const
01299       { return _M_h1()(__k); }
01300 
01301       std::size_t
01302       _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
01303       { return _M_h2()(__c, __n); }
01304 
01305       std::size_t
01306       _M_bucket_index(const __node_type* __p, std::size_t __n) const
01307         noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>()))
01308                   && noexcept(declval<const _H2&>()((__hash_code)0,
01309                                                     (std::size_t)0)) )
01310       { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); }
01311 
01312       void
01313       _M_store_code(__node_type*, __hash_code) const
01314       { }
01315 
01316       void
01317       _M_copy_code(__node_type*, const __node_type*) const
01318       { }
01319 
01320       void
01321       _M_swap(_Hash_code_base& __x)
01322       {
01323         std::swap(_M_extract(), __x._M_extract());
01324         std::swap(_M_h1(), __x._M_h1());
01325         std::swap(_M_h2(), __x._M_h2());
01326       }
01327 
01328       const _ExtractKey&
01329       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
01330 
01331       _ExtractKey&
01332       _M_extract() { return __ebo_extract_key::_S_get(*this); }
01333 
01334       const _H1&
01335       _M_h1() const { return __ebo_h1::_S_cget(*this); }
01336 
01337       _H1&
01338       _M_h1() { return __ebo_h1::_S_get(*this); }
01339 
01340       const _H2&
01341       _M_h2() const { return __ebo_h2::_S_cget(*this); }
01342 
01343       _H2&
01344       _M_h2() { return __ebo_h2::_S_get(*this); }
01345     };
01346 
01347   /// Specialization: hash function and range-hashing function,
01348   /// caching hash codes.  H is provided but ignored.  Provides
01349   /// typedef and accessor required by C++ 11.
01350   template<typename _Key, typename _Value, typename _ExtractKey,
01351            typename _H1, typename _H2>
01352     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
01353                            _Default_ranged_hash, true>
01354     : private _Hashtable_ebo_helper<0, _ExtractKey>,
01355       private _Hashtable_ebo_helper<1, _H1>,
01356       private _Hashtable_ebo_helper<2, _H2>
01357     {
01358     private:
01359       // Gives the local iterator implementation access to _M_h2().
01360       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
01361                                          _Default_ranged_hash, true>;
01362 
01363       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
01364       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
01365       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
01366 
01367     public:
01368       typedef _H1                                       hasher;
01369 
01370       hasher
01371       hash_function() const
01372       { return _M_h1(); }
01373 
01374     protected:
01375       typedef std::size_t                               __hash_code;
01376       typedef _Hash_node<_Value, true>                  __node_type;
01377 
01378       // We need the default constructor for _Hashtable default constructor.
01379       _Hash_code_base() = default;
01380       _Hash_code_base(const _ExtractKey& __ex,
01381                       const _H1& __h1, const _H2& __h2,
01382                       const _Default_ranged_hash&)
01383       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
01384 
01385       __hash_code
01386       _M_hash_code(const _Key& __k) const
01387       { return _M_h1()(__k); }
01388 
01389       std::size_t
01390       _M_bucket_index(const _Key&, __hash_code __c,
01391                       std::size_t __n) const
01392       { return _M_h2()(__c, __n); }
01393 
01394       std::size_t
01395       _M_bucket_index(const __node_type* __p, std::size_t __n) const
01396         noexcept( noexcept(declval<const _H2&>()((__hash_code)0,
01397                                                  (std::size_t)0)) )
01398       { return _M_h2()(__p->_M_hash_code, __n); }
01399 
01400       void
01401       _M_store_code(__node_type* __n, __hash_code __c) const
01402       { __n->_M_hash_code = __c; }
01403 
01404       void
01405       _M_copy_code(__node_type* __to, const __node_type* __from) const
01406       { __to->_M_hash_code = __from->_M_hash_code; }
01407 
01408       void
01409       _M_swap(_Hash_code_base& __x)
01410       {
01411         std::swap(_M_extract(), __x._M_extract());
01412         std::swap(_M_h1(), __x._M_h1());
01413         std::swap(_M_h2(), __x._M_h2());
01414       }
01415 
01416       const _ExtractKey&
01417       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
01418 
01419       _ExtractKey&
01420       _M_extract() { return __ebo_extract_key::_S_get(*this); }
01421 
01422       const _H1&
01423       _M_h1() const { return __ebo_h1::_S_cget(*this); }
01424 
01425       _H1&
01426       _M_h1() { return __ebo_h1::_S_get(*this); }
01427 
01428       const _H2&
01429       _M_h2() const { return __ebo_h2::_S_cget(*this); }
01430 
01431       _H2&
01432       _M_h2() { return __ebo_h2::_S_get(*this); }
01433     };
01434 
01435   /**
01436    *  Primary class template _Equal_helper.
01437    *
01438    */
01439   template <typename _Key, typename _Value, typename _ExtractKey,
01440             typename _Equal, typename _HashCodeType,
01441             bool __cache_hash_code>
01442   struct _Equal_helper;
01443 
01444   /// Specialization.
01445   template<typename _Key, typename _Value, typename _ExtractKey,
01446            typename _Equal, typename _HashCodeType>
01447   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
01448   {
01449     static bool
01450     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
01451               const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
01452     { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); }
01453   };
01454 
01455   /// Specialization.
01456   template<typename _Key, typename _Value, typename _ExtractKey,
01457            typename _Equal, typename _HashCodeType>
01458   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
01459   {
01460     static bool
01461     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
01462               const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
01463     { return __eq(__k, __extract(__n->_M_v())); }
01464   };
01465 
01466 
01467   /// Partial specialization used when nodes contain a cached hash code.
01468   template<typename _Key, typename _Value, typename _ExtractKey,
01469            typename _H1, typename _H2, typename _Hash>
01470     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
01471                                 _H1, _H2, _Hash, true>
01472     : private _Hashtable_ebo_helper<0, _H2>
01473     {
01474     protected:
01475       using __base_type = _Hashtable_ebo_helper<0, _H2>;
01476       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
01477                                                _H1, _H2, _Hash, true>;
01478 
01479       _Local_iterator_base() = default;
01480       _Local_iterator_base(const __hash_code_base& __base,
01481                            _Hash_node<_Value, true>* __p,
01482                            std::size_t __bkt, std::size_t __bkt_count)
01483       : __base_type(__base._M_h2()),
01484         _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
01485 
01486       void
01487       _M_incr()
01488       {
01489         _M_cur = _M_cur->_M_next();
01490         if (_M_cur)
01491           {
01492             std::size_t __bkt
01493               = __base_type::_S_get(*this)(_M_cur->_M_hash_code,
01494                                            _M_bucket_count);
01495             if (__bkt != _M_bucket)
01496               _M_cur = nullptr;
01497           }
01498       }
01499 
01500       _Hash_node<_Value, true>*  _M_cur;
01501       std::size_t _M_bucket;
01502       std::size_t _M_bucket_count;
01503 
01504     public:
01505       const void*
01506       _M_curr() const { return _M_cur; }  // for equality ops
01507 
01508       std::size_t
01509       _M_get_bucket() const { return _M_bucket; }  // for debug mode
01510     };
01511 
01512   // Uninitialized storage for a _Hash_code_base.
01513   // This type is DefaultConstructible and Assignable even if the
01514   // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
01515   // can be DefaultConstructible and Assignable.
01516   template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
01517     struct _Hash_code_storage
01518     {
01519       __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
01520 
01521       _Tp*
01522       _M_h() { return _M_storage._M_ptr(); }
01523 
01524       const _Tp*
01525       _M_h() const { return _M_storage._M_ptr(); }
01526     };
01527 
01528   // Empty partial specialization for empty _Hash_code_base types.
01529   template<typename _Tp>
01530     struct _Hash_code_storage<_Tp, true>
01531     {
01532       static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
01533 
01534       // As _Tp is an empty type there will be no bytes written/read through
01535       // the cast pointer, so no strict-aliasing violation.
01536       _Tp*
01537       _M_h() { return reinterpret_cast<_Tp*>(this); }
01538 
01539       const _Tp*
01540       _M_h() const { return reinterpret_cast<const _Tp*>(this); }
01541     };
01542 
01543   template<typename _Key, typename _Value, typename _ExtractKey,
01544            typename _H1, typename _H2, typename _Hash>
01545     using __hash_code_for_local_iter
01546       = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
01547                                            _H1, _H2, _Hash, false>>;
01548 
01549   // Partial specialization used when hash codes are not cached
01550   template<typename _Key, typename _Value, typename _ExtractKey,
01551            typename _H1, typename _H2, typename _Hash>
01552     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
01553                                 _H1, _H2, _Hash, false>
01554     : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash>
01555     {
01556     protected:
01557       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
01558                                                _H1, _H2, _Hash, false>;
01559 
01560       _Local_iterator_base() : _M_bucket_count(-1) { }
01561 
01562       _Local_iterator_base(const __hash_code_base& __base,
01563                            _Hash_node<_Value, false>* __p,
01564                            std::size_t __bkt, std::size_t __bkt_count)
01565       : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
01566       { _M_init(__base); }
01567 
01568       ~_Local_iterator_base()
01569       {
01570         if (_M_bucket_count != -1)
01571           _M_destroy();
01572       }
01573 
01574       _Local_iterator_base(const _Local_iterator_base& __iter)
01575       : _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket),
01576         _M_bucket_count(__iter._M_bucket_count)
01577       {
01578         if (_M_bucket_count != -1)
01579           _M_init(*__iter._M_h());
01580       }
01581 
01582       _Local_iterator_base&
01583       operator=(const _Local_iterator_base& __iter)
01584       {
01585         if (_M_bucket_count != -1)
01586           _M_destroy();
01587         _M_cur = __iter._M_cur;
01588         _M_bucket = __iter._M_bucket;
01589         _M_bucket_count = __iter._M_bucket_count;
01590         if (_M_bucket_count != -1)
01591           _M_init(*__iter._M_h());
01592         return *this;
01593       }
01594 
01595       void
01596       _M_incr()
01597       {
01598         _M_cur = _M_cur->_M_next();
01599         if (_M_cur)
01600           {
01601             std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur,
01602                                                               _M_bucket_count);
01603             if (__bkt != _M_bucket)
01604               _M_cur = nullptr;
01605           }
01606       }
01607 
01608       _Hash_node<_Value, false>*  _M_cur;
01609       std::size_t _M_bucket;
01610       std::size_t _M_bucket_count;
01611 
01612       void
01613       _M_init(const __hash_code_base& __base)
01614       { ::new(this->_M_h()) __hash_code_base(__base); }
01615 
01616       void
01617       _M_destroy() { this->_M_h()->~__hash_code_base(); }
01618 
01619     public:
01620       const void*
01621       _M_curr() const { return _M_cur; }  // for equality ops and debug mode
01622 
01623       std::size_t
01624       _M_get_bucket() const { return _M_bucket; }  // for debug mode
01625     };
01626 
01627   template<typename _Key, typename _Value, typename _ExtractKey,
01628            typename _H1, typename _H2, typename _Hash, bool __cache>
01629     inline bool
01630     operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
01631                                           _H1, _H2, _Hash, __cache>& __x,
01632                const _Local_iterator_base<_Key, _Value, _ExtractKey,
01633                                           _H1, _H2, _Hash, __cache>& __y)
01634     { return __x._M_curr() == __y._M_curr(); }
01635 
01636   template<typename _Key, typename _Value, typename _ExtractKey,
01637            typename _H1, typename _H2, typename _Hash, bool __cache>
01638     inline bool
01639     operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
01640                                           _H1, _H2, _Hash, __cache>& __x,
01641                const _Local_iterator_base<_Key, _Value, _ExtractKey,
01642                                           _H1, _H2, _Hash, __cache>& __y)
01643     { return __x._M_curr() != __y._M_curr(); }
01644 
01645   /// local iterators
01646   template<typename _Key, typename _Value, typename _ExtractKey,
01647            typename _H1, typename _H2, typename _Hash,
01648            bool __constant_iterators, bool __cache>
01649     struct _Local_iterator
01650     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
01651                                   _H1, _H2, _Hash, __cache>
01652     {
01653     private:
01654       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
01655                                                _H1, _H2, _Hash, __cache>;
01656       using __hash_code_base = typename __base_type::__hash_code_base;
01657     public:
01658       typedef _Value                                    value_type;
01659       typedef typename std::conditional<__constant_iterators,
01660                                         const _Value*, _Value*>::type
01661                                                        pointer;
01662       typedef typename std::conditional<__constant_iterators,
01663                                         const _Value&, _Value&>::type
01664                                                        reference;
01665       typedef std::ptrdiff_t                            difference_type;
01666       typedef std::forward_iterator_tag                 iterator_category;
01667 
01668       _Local_iterator() = default;
01669 
01670       _Local_iterator(const __hash_code_base& __base,
01671                       _Hash_node<_Value, __cache>* __p,
01672                       std::size_t __bkt, std::size_t __bkt_count)
01673         : __base_type(__base, __p, __bkt, __bkt_count)
01674       { }
01675 
01676       reference
01677       operator*() const
01678       { return this->_M_cur->_M_v(); }
01679 
01680       pointer
01681       operator->() const
01682       { return this->_M_cur->_M_valptr(); }
01683 
01684       _Local_iterator&
01685       operator++()
01686       {
01687         this->_M_incr();
01688         return *this;
01689       }
01690 
01691       _Local_iterator
01692       operator++(int)
01693       {
01694         _Local_iterator __tmp(*this);
01695         this->_M_incr();
01696         return __tmp;
01697       }
01698     };
01699 
01700   /// local const_iterators
01701   template<typename _Key, typename _Value, typename _ExtractKey,
01702            typename _H1, typename _H2, typename _Hash,
01703            bool __constant_iterators, bool __cache>
01704     struct _Local_const_iterator
01705     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
01706                                   _H1, _H2, _Hash, __cache>
01707     {
01708     private:
01709       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
01710                                                _H1, _H2, _Hash, __cache>;
01711       using __hash_code_base = typename __base_type::__hash_code_base;
01712 
01713     public:
01714       typedef _Value                                    value_type;
01715       typedef const _Value*                             pointer;
01716       typedef const _Value&                             reference;
01717       typedef std::ptrdiff_t                            difference_type;
01718       typedef std::forward_iterator_tag                 iterator_category;
01719 
01720       _Local_const_iterator() = default;
01721 
01722       _Local_const_iterator(const __hash_code_base& __base,
01723                             _Hash_node<_Value, __cache>* __p,
01724                             std::size_t __bkt, std::size_t __bkt_count)
01725         : __base_type(__base, __p, __bkt, __bkt_count)
01726       { }
01727 
01728       _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
01729                                                   _H1, _H2, _Hash,
01730                                                   __constant_iterators,
01731                                                   __cache>& __x)
01732         : __base_type(__x)
01733       { }
01734 
01735       reference
01736       operator*() const
01737       { return this->_M_cur->_M_v(); }
01738 
01739       pointer
01740       operator->() const
01741       { return this->_M_cur->_M_valptr(); }
01742 
01743       _Local_const_iterator&
01744       operator++()
01745       {
01746         this->_M_incr();
01747         return *this;
01748       }
01749 
01750       _Local_const_iterator
01751       operator++(int)
01752       {
01753         _Local_const_iterator __tmp(*this);
01754         this->_M_incr();
01755         return __tmp;
01756       }
01757     };
01758 
01759   /**
01760    *  Primary class template _Hashtable_base.
01761    *
01762    *  Helper class adding management of _Equal functor to
01763    *  _Hash_code_base type.
01764    *
01765    *  Base class templates are:
01766    *    - __detail::_Hash_code_base
01767    *    - __detail::_Hashtable_ebo_helper
01768    */
01769   template<typename _Key, typename _Value,
01770            typename _ExtractKey, typename _Equal,
01771            typename _H1, typename _H2, typename _Hash, typename _Traits>
01772   struct _Hashtable_base
01773   : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
01774                            _Traits::__hash_cached::value>,
01775     private _Hashtable_ebo_helper<0, _Equal>
01776   {
01777   public:
01778     typedef _Key                                        key_type;
01779     typedef _Value                                      value_type;
01780     typedef _Equal                                      key_equal;
01781     typedef std::size_t                                 size_type;
01782     typedef std::ptrdiff_t                              difference_type;
01783 
01784     using __traits_type = _Traits;
01785     using __hash_cached = typename __traits_type::__hash_cached;
01786     using __constant_iterators = typename __traits_type::__constant_iterators;
01787     using __unique_keys = typename __traits_type::__unique_keys;
01788 
01789     using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
01790                                              _H1, _H2, _Hash,
01791                                              __hash_cached::value>;
01792 
01793     using __hash_code = typename __hash_code_base::__hash_code;
01794     using __node_type = typename __hash_code_base::__node_type;
01795 
01796     using iterator = __detail::_Node_iterator<value_type,
01797                                               __constant_iterators::value,
01798                                               __hash_cached::value>;
01799 
01800     using const_iterator = __detail::_Node_const_iterator<value_type,
01801                                                    __constant_iterators::value,
01802                                                    __hash_cached::value>;
01803 
01804     using local_iterator = __detail::_Local_iterator<key_type, value_type,
01805                                                   _ExtractKey, _H1, _H2, _Hash,
01806                                                   __constant_iterators::value,
01807                                                      __hash_cached::value>;
01808 
01809     using const_local_iterator = __detail::_Local_const_iterator<key_type,
01810                                                                  value_type,
01811                                         _ExtractKey, _H1, _H2, _Hash,
01812                                         __constant_iterators::value,
01813                                         __hash_cached::value>;
01814 
01815     using __ireturn_type = typename std::conditional<__unique_keys::value,
01816                                                      std::pair<iterator, bool>,
01817                                                      iterator>::type;
01818   private:
01819     using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
01820     using _EqualHelper =  _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
01821                                         __hash_code, __hash_cached::value>;
01822 
01823   protected:
01824     _Hashtable_base() = default;
01825     _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
01826                     const _Hash& __hash, const _Equal& __eq)
01827     : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
01828     { }
01829 
01830     bool
01831     _M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
01832     {
01833       return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
01834                                      __k, __c, __n);
01835     }
01836 
01837     void
01838     _M_swap(_Hashtable_base& __x)
01839     {
01840       __hash_code_base::_M_swap(__x);
01841       std::swap(_M_eq(), __x._M_eq());
01842     }
01843 
01844     const _Equal&
01845     _M_eq() const { return _EqualEBO::_S_cget(*this); }
01846 
01847     _Equal&
01848     _M_eq() { return _EqualEBO::_S_get(*this); }
01849   };
01850 
01851   /**
01852    *  struct _Equality_base.
01853    *
01854    *  Common types and functions for class _Equality.
01855    */
01856   struct _Equality_base
01857   {
01858   protected:
01859     template<typename _Uiterator>
01860       static bool
01861       _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
01862   };
01863 
01864   // See std::is_permutation in N3068.
01865   template<typename _Uiterator>
01866     bool
01867     _Equality_base::
01868     _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
01869                       _Uiterator __first2)
01870     {
01871       for (; __first1 != __last1; ++__first1, ++__first2)
01872         if (!(*__first1 == *__first2))
01873           break;
01874 
01875       if (__first1 == __last1)
01876         return true;
01877 
01878       _Uiterator __last2 = __first2;
01879       std::advance(__last2, std::distance(__first1, __last1));
01880 
01881       for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
01882         {
01883           _Uiterator __tmp =  __first1;
01884           while (__tmp != __it1 && !bool(*__tmp == *__it1))
01885             ++__tmp;
01886 
01887           // We've seen this one before.
01888           if (__tmp != __it1)
01889             continue;
01890 
01891           std::ptrdiff_t __n2 = 0;
01892           for (__tmp = __first2; __tmp != __last2; ++__tmp)
01893             if (*__tmp == *__it1)
01894               ++__n2;
01895 
01896           if (!__n2)
01897             return false;
01898 
01899           std::ptrdiff_t __n1 = 0;
01900           for (__tmp = __it1; __tmp != __last1; ++__tmp)
01901             if (*__tmp == *__it1)
01902               ++__n1;
01903 
01904           if (__n1 != __n2)
01905             return false;
01906         }
01907       return true;
01908     }
01909 
01910   /**
01911    *  Primary class template  _Equality.
01912    *
01913    *  This is for implementing equality comparison for unordered
01914    *  containers, per N3068, by John Lakos and Pablo Halpern.
01915    *  Algorithmically, we follow closely the reference implementations
01916    *  therein.
01917    */
01918   template<typename _Key, typename _Value, typename _Alloc,
01919            typename _ExtractKey, typename _Equal,
01920            typename _H1, typename _H2, typename _Hash,
01921            typename _RehashPolicy, typename _Traits,
01922            bool _Unique_keys = _Traits::__unique_keys::value>
01923     struct _Equality;
01924 
01925   /// Specialization.
01926   template<typename _Key, typename _Value, typename _Alloc,
01927            typename _ExtractKey, typename _Equal,
01928            typename _H1, typename _H2, typename _Hash,
01929            typename _RehashPolicy, typename _Traits>
01930     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01931                      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
01932     {
01933       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01934                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
01935 
01936       bool
01937       _M_equal(const __hashtable&) const;
01938     };
01939 
01940   template<typename _Key, typename _Value, typename _Alloc,
01941            typename _ExtractKey, typename _Equal,
01942            typename _H1, typename _H2, typename _Hash,
01943            typename _RehashPolicy, typename _Traits>
01944     bool
01945     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01946               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
01947     _M_equal(const __hashtable& __other) const
01948     {
01949       const __hashtable* __this = static_cast<const __hashtable*>(this);
01950 
01951       if (__this->size() != __other.size())
01952         return false;
01953 
01954       for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
01955         {
01956           const auto __ity = __other.find(_ExtractKey()(*__itx));
01957           if (__ity == __other.end() || !bool(*__ity == *__itx))
01958             return false;
01959         }
01960       return true;
01961     }
01962 
01963   /// Specialization.
01964   template<typename _Key, typename _Value, typename _Alloc,
01965            typename _ExtractKey, typename _Equal,
01966            typename _H1, typename _H2, typename _Hash,
01967            typename _RehashPolicy, typename _Traits>
01968     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01969                      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
01970     : public _Equality_base
01971     {
01972       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01973                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
01974 
01975       bool
01976       _M_equal(const __hashtable&) const;
01977     };
01978 
01979   template<typename _Key, typename _Value, typename _Alloc,
01980            typename _ExtractKey, typename _Equal,
01981            typename _H1, typename _H2, typename _Hash,
01982            typename _RehashPolicy, typename _Traits>
01983     bool
01984     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01985               _H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
01986     _M_equal(const __hashtable& __other) const
01987     {
01988       const __hashtable* __this = static_cast<const __hashtable*>(this);
01989 
01990       if (__this->size() != __other.size())
01991         return false;
01992 
01993       for (auto __itx = __this->begin(); __itx != __this->end();)
01994         {
01995           const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
01996           const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
01997 
01998           if (std::distance(__xrange.first, __xrange.second)
01999               != std::distance(__yrange.first, __yrange.second))
02000             return false;
02001 
02002           if (!_S_is_permutation(__xrange.first, __xrange.second,
02003                                  __yrange.first))
02004             return false;
02005 
02006           __itx = __xrange.second;
02007         }
02008       return true;
02009     }
02010 
02011   /**
02012    * This type deals with all allocation and keeps an allocator instance through
02013    * inheritance to benefit from EBO when possible.
02014    */
02015   template<typename _NodeAlloc>
02016     struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
02017     {
02018     private:
02019       using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
02020     public:
02021       using __node_type = typename _NodeAlloc::value_type;
02022       using __node_alloc_type = _NodeAlloc;
02023       // Use __gnu_cxx to benefit from _S_always_equal and al.
02024       using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
02025 
02026       using __value_alloc_traits = typename __node_alloc_traits::template
02027         rebind_traits<typename __node_type::value_type>;
02028 
02029       using __node_base = __detail::_Hash_node_base;
02030       using __bucket_type = __node_base*;      
02031       using __bucket_alloc_type =
02032         __alloc_rebind<__node_alloc_type, __bucket_type>;
02033       using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>;
02034 
02035       _Hashtable_alloc() = default;
02036       _Hashtable_alloc(const _Hashtable_alloc&) = default;
02037       _Hashtable_alloc(_Hashtable_alloc&&) = default;
02038 
02039       template<typename _Alloc>
02040         _Hashtable_alloc(_Alloc&& __a)
02041           : __ebo_node_alloc(std::forward<_Alloc>(__a))
02042         { }
02043 
02044       __node_alloc_type&
02045       _M_node_allocator()
02046       { return __ebo_node_alloc::_S_get(*this); }
02047 
02048       const __node_alloc_type&
02049       _M_node_allocator() const
02050       { return __ebo_node_alloc::_S_cget(*this); }
02051 
02052       template<typename... _Args>
02053         __node_type*
02054         _M_allocate_node(_Args&&... __args);
02055 
02056       void
02057       _M_deallocate_node(__node_type* __n);
02058 
02059       // Deallocate the linked list of nodes pointed to by __n
02060       void
02061       _M_deallocate_nodes(__node_type* __n);
02062 
02063       __bucket_type*
02064       _M_allocate_buckets(std::size_t __n);
02065 
02066       void
02067       _M_deallocate_buckets(__bucket_type*, std::size_t __n);
02068     };
02069 
02070   // Definitions of class template _Hashtable_alloc's out-of-line member
02071   // functions.
02072   template<typename _NodeAlloc>
02073     template<typename... _Args>
02074       typename _Hashtable_alloc<_NodeAlloc>::__node_type*
02075       _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
02076       {
02077         auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
02078         __node_type* __n = std::__to_address(__nptr);
02079         __try
02080           {
02081             ::new ((void*)__n) __node_type;
02082             __node_alloc_traits::construct(_M_node_allocator(),
02083                                            __n->_M_valptr(),
02084                                            std::forward<_Args>(__args)...);
02085             return __n;
02086           }
02087         __catch(...)
02088           {
02089             __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
02090             __throw_exception_again;
02091           }
02092       }
02093 
02094   template<typename _NodeAlloc>
02095     void
02096     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
02097     {
02098       typedef typename __node_alloc_traits::pointer _Ptr;
02099       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
02100       __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
02101       __n->~__node_type();
02102       __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
02103     }
02104 
02105   template<typename _NodeAlloc>
02106     void
02107     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type* __n)
02108     {
02109       while (__n)
02110         {
02111           __node_type* __tmp = __n;
02112           __n = __n->_M_next();
02113           _M_deallocate_node(__tmp);
02114         }
02115     }
02116 
02117   template<typename _NodeAlloc>
02118     typename _Hashtable_alloc<_NodeAlloc>::__bucket_type*
02119     _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n)
02120     {
02121       __bucket_alloc_type __alloc(_M_node_allocator());
02122 
02123       auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
02124       __bucket_type* __p = std::__to_address(__ptr);
02125       __builtin_memset(__p, 0, __n * sizeof(__bucket_type));
02126       return __p;
02127     }
02128 
02129   template<typename _NodeAlloc>
02130     void
02131     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts,
02132                                                         std::size_t __n)
02133     {
02134       typedef typename __bucket_alloc_traits::pointer _Ptr;
02135       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
02136       __bucket_alloc_type __alloc(_M_node_allocator());
02137       __bucket_alloc_traits::deallocate(__alloc, __ptr, __n);
02138     }
02139 
02140  //@} hashtable-detail
02141 } // namespace __detail
02142 _GLIBCXX_END_NAMESPACE_VERSION
02143 } // namespace std
02144 
02145 #endif // _HASHTABLE_POLICY_H