libstdc++
hashtable.h
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00001 // hashtable.h header -*- C++ -*-
00002 
00003 // Copyright (C) 2007-2015 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.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly. @headername{unordered_map, unordered_set}
00028  */
00029 
00030 #ifndef _HASHTABLE_H
00031 #define _HASHTABLE_H 1
00032 
00033 #pragma GCC system_header
00034 
00035 #include <bits/hashtable_policy.h>
00036 
00037 namespace std _GLIBCXX_VISIBILITY(default)
00038 {
00039 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00040 
00041   template<typename _Tp, typename _Hash>
00042     using __cache_default
00043       =  __not_<__and_<// Do not cache for fast hasher.
00044                        __is_fast_hash<_Hash>,
00045                        // Mandatory to have erase not throwing.
00046                        __detail::__is_noexcept_hash<_Tp, _Hash>>>;
00047 
00048   /**
00049    *  Primary class template _Hashtable.
00050    *
00051    *  @ingroup hashtable-detail
00052    *
00053    *  @tparam _Value  CopyConstructible type.
00054    *
00055    *  @tparam _Key    CopyConstructible type.
00056    *
00057    *  @tparam _Alloc  An allocator type
00058    *  ([lib.allocator.requirements]) whose _Alloc::value_type is
00059    *  _Value.  As a conforming extension, we allow for
00060    *  _Alloc::value_type != _Value.
00061    *
00062    *  @tparam _ExtractKey  Function object that takes an object of type
00063    *  _Value and returns a value of type _Key.
00064    *
00065    *  @tparam _Equal  Function object that takes two objects of type k
00066    *  and returns a bool-like value that is true if the two objects
00067    *  are considered equal.
00068    *
00069    *  @tparam _H1  The hash function. A unary function object with
00070    *  argument type _Key and result type size_t. Return values should
00071    *  be distributed over the entire range [0, numeric_limits<size_t>:::max()].
00072    *
00073    *  @tparam _H2  The range-hashing function (in the terminology of
00074    *  Tavori and Dreizin).  A binary function object whose argument
00075    *  types and result type are all size_t.  Given arguments r and N,
00076    *  the return value is in the range [0, N).
00077    *
00078    *  @tparam _Hash  The ranged hash function (Tavori and Dreizin). A
00079    *  binary function whose argument types are _Key and size_t and
00080    *  whose result type is size_t.  Given arguments k and N, the
00081    *  return value is in the range [0, N).  Default: hash(k, N) =
00082    *  h2(h1(k), N).  If _Hash is anything other than the default, _H1
00083    *  and _H2 are ignored.
00084    *
00085    *  @tparam _RehashPolicy  Policy class with three members, all of
00086    *  which govern the bucket count. _M_next_bkt(n) returns a bucket
00087    *  count no smaller than n.  _M_bkt_for_elements(n) returns a
00088    *  bucket count appropriate for an element count of n.
00089    *  _M_need_rehash(n_bkt, n_elt, n_ins) determines whether, if the
00090    *  current bucket count is n_bkt and the current element count is
00091    *  n_elt, we need to increase the bucket count.  If so, returns
00092    *  make_pair(true, n), where n is the new bucket count.  If not,
00093    *  returns make_pair(false, <anything>)
00094    *
00095    *  @tparam _Traits  Compile-time class with three boolean
00096    *  std::integral_constant members:  __cache_hash_code, __constant_iterators,
00097    *   __unique_keys.
00098    *
00099    *  Each _Hashtable data structure has:
00100    *
00101    *  - _Bucket[]       _M_buckets
00102    *  - _Hash_node_base _M_before_begin
00103    *  - size_type       _M_bucket_count
00104    *  - size_type       _M_element_count
00105    *
00106    *  with _Bucket being _Hash_node* and _Hash_node containing:
00107    *
00108    *  - _Hash_node*   _M_next
00109    *  - Tp            _M_value
00110    *  - size_t        _M_hash_code if cache_hash_code is true
00111    *
00112    *  In terms of Standard containers the hashtable is like the aggregation of:
00113    *
00114    *  - std::forward_list<_Node> containing the elements
00115    *  - std::vector<std::forward_list<_Node>::iterator> representing the buckets
00116    *
00117    *  The non-empty buckets contain the node before the first node in the
00118    *  bucket. This design makes it possible to implement something like a
00119    *  std::forward_list::insert_after on container insertion and
00120    *  std::forward_list::erase_after on container erase
00121    *  calls. _M_before_begin is equivalent to
00122    *  std::forward_list::before_begin. Empty buckets contain
00123    *  nullptr.  Note that one of the non-empty buckets contains
00124    *  &_M_before_begin which is not a dereferenceable node so the
00125    *  node pointer in a bucket shall never be dereferenced, only its
00126    *  next node can be.
00127    *
00128    *  Walking through a bucket's nodes requires a check on the hash code to
00129    *  see if each node is still in the bucket. Such a design assumes a
00130    *  quite efficient hash functor and is one of the reasons it is
00131    *  highly advisable to set __cache_hash_code to true.
00132    *
00133    *  The container iterators are simply built from nodes. This way
00134    *  incrementing the iterator is perfectly efficient independent of
00135    *  how many empty buckets there are in the container.
00136    *
00137    *  On insert we compute the element's hash code and use it to find the
00138    *  bucket index. If the element must be inserted in an empty bucket
00139    *  we add it at the beginning of the singly linked list and make the
00140    *  bucket point to _M_before_begin. The bucket that used to point to
00141    *  _M_before_begin, if any, is updated to point to its new before
00142    *  begin node.
00143    *
00144    *  On erase, the simple iterator design requires using the hash
00145    *  functor to get the index of the bucket to update. For this
00146    *  reason, when __cache_hash_code is set to false the hash functor must
00147    *  not throw and this is enforced by a static assertion.
00148    *
00149    *  Functionality is implemented by decomposition into base classes,
00150    *  where the derived _Hashtable class is used in _Map_base,
00151    *  _Insert, _Rehash_base, and _Equality base classes to access the
00152    *  "this" pointer. _Hashtable_base is used in the base classes as a
00153    *  non-recursive, fully-completed-type so that detailed nested type
00154    *  information, such as iterator type and node type, can be
00155    *  used. This is similar to the "Curiously Recurring Template
00156    *  Pattern" (CRTP) technique, but uses a reconstructed, not
00157    *  explicitly passed, template pattern.
00158    *
00159    *  Base class templates are: 
00160    *    - __detail::_Hashtable_base
00161    *    - __detail::_Map_base
00162    *    - __detail::_Insert
00163    *    - __detail::_Rehash_base
00164    *    - __detail::_Equality
00165    */
00166   template<typename _Key, typename _Value, typename _Alloc,
00167            typename _ExtractKey, typename _Equal,
00168            typename _H1, typename _H2, typename _Hash,
00169            typename _RehashPolicy, typename _Traits>
00170     class _Hashtable
00171     : public __detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal,
00172                                        _H1, _H2, _Hash, _Traits>,
00173       public __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00174                                  _H1, _H2, _Hash, _RehashPolicy, _Traits>,
00175       public __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00176                                _H1, _H2, _Hash, _RehashPolicy, _Traits>,
00177       public __detail::_Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00178                                     _H1, _H2, _Hash, _RehashPolicy, _Traits>,
00179       public __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00180                                  _H1, _H2, _Hash, _RehashPolicy, _Traits>,
00181       private __detail::_Hashtable_alloc<
00182         typename __alloctr_rebind<_Alloc,
00183           __detail::_Hash_node<_Value,
00184                                _Traits::__hash_cached::value> >::__type>
00185     {
00186       using __traits_type = _Traits;
00187       using __hash_cached = typename __traits_type::__hash_cached;
00188       using __node_type = __detail::_Hash_node<_Value, __hash_cached::value>;
00189       using __node_alloc_type =
00190         typename __alloctr_rebind<_Alloc, __node_type>::__type;
00191 
00192       using __hashtable_alloc = __detail::_Hashtable_alloc<__node_alloc_type>;
00193 
00194       using __value_alloc_traits =
00195         typename __hashtable_alloc::__value_alloc_traits;
00196       using __node_alloc_traits =
00197         typename __hashtable_alloc::__node_alloc_traits;
00198       using __node_base = typename __hashtable_alloc::__node_base;
00199       using __bucket_type = typename __hashtable_alloc::__bucket_type;
00200 
00201     public:
00202       typedef _Key                                              key_type;
00203       typedef _Value                                            value_type;
00204       typedef _Alloc                                            allocator_type;
00205       typedef _Equal                                            key_equal;
00206 
00207       // mapped_type, if present, comes from _Map_base.
00208       // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
00209       typedef typename __value_alloc_traits::pointer            pointer;
00210       typedef typename __value_alloc_traits::const_pointer      const_pointer;
00211       typedef value_type&                                       reference;
00212       typedef const value_type&                                 const_reference;
00213 
00214     private:
00215       using __rehash_type = _RehashPolicy;
00216       using __rehash_state = typename __rehash_type::_State;
00217 
00218       using __constant_iterators = typename __traits_type::__constant_iterators;
00219       using __unique_keys = typename __traits_type::__unique_keys;
00220 
00221       using __key_extract = typename std::conditional<
00222                                              __constant_iterators::value,
00223                                              __detail::_Identity,
00224                                              __detail::_Select1st>::type;
00225 
00226       using __hashtable_base = __detail::
00227 			       _Hashtable_base<_Key, _Value, _ExtractKey,
00228                                               _Equal, _H1, _H2, _Hash, _Traits>;
00229 
00230       using __hash_code_base =  typename __hashtable_base::__hash_code_base;
00231       using __hash_code =  typename __hashtable_base::__hash_code;
00232       using __ireturn_type = typename __hashtable_base::__ireturn_type;
00233 
00234       using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
00235                                              _Equal, _H1, _H2, _Hash,
00236                                              _RehashPolicy, _Traits>;
00237 
00238       using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
00239                                                    _ExtractKey, _Equal,
00240                                                    _H1, _H2, _Hash,
00241                                                    _RehashPolicy, _Traits>;
00242 
00243       using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
00244                                             _Equal, _H1, _H2, _Hash,
00245                                             _RehashPolicy, _Traits>;
00246 
00247       using __reuse_or_alloc_node_type =
00248         __detail::_ReuseOrAllocNode<__node_alloc_type>;
00249 
00250       // Metaprogramming for picking apart hash caching.
00251       template<typename _Cond>
00252         using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
00253 
00254       template<typename _Cond>
00255         using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
00256 
00257       // Compile-time diagnostics.
00258 
00259       // _Hash_code_base has everything protected, so use this derived type to
00260       // access it.
00261       struct __hash_code_base_access : __hash_code_base
00262       { using __hash_code_base::_M_bucket_index; };
00263 
00264       // Getting a bucket index from a node shall not throw because it is used
00265       // in methods (erase, swap...) that shall not throw.
00266       static_assert(noexcept(declval<const __hash_code_base_access&>()
00267                              ._M_bucket_index((const __node_type*)nullptr,
00268                                               (std::size_t)0)),
00269                     "Cache the hash code or qualify your functors involved"
00270                     " in hash code and bucket index computation with noexcept");
00271 
00272       // Following two static assertions are necessary to guarantee
00273       // that local_iterator will be default constructible.
00274 
00275       // When hash codes are cached local iterator inherits from H2 functor
00276       // which must then be default constructible.
00277       static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
00278                     "Functor used to map hash code to bucket index"
00279                     " must be default constructible");
00280 
00281       template<typename _Keya, typename _Valuea, typename _Alloca,
00282                typename _ExtractKeya, typename _Equala,
00283                typename _H1a, typename _H2a, typename _Hasha,
00284                typename _RehashPolicya, typename _Traitsa,
00285                bool _Unique_keysa>
00286         friend struct __detail::_Map_base;
00287 
00288       template<typename _Keya, typename _Valuea, typename _Alloca,
00289                typename _ExtractKeya, typename _Equala,
00290                typename _H1a, typename _H2a, typename _Hasha,
00291                typename _RehashPolicya, typename _Traitsa>
00292         friend struct __detail::_Insert_base;
00293 
00294       template<typename _Keya, typename _Valuea, typename _Alloca,
00295                typename _ExtractKeya, typename _Equala,
00296                typename _H1a, typename _H2a, typename _Hasha,
00297                typename _RehashPolicya, typename _Traitsa,
00298                bool _Constant_iteratorsa, bool _Unique_keysa>
00299         friend struct __detail::_Insert;
00300 
00301     public:
00302       using size_type = typename __hashtable_base::size_type;
00303       using difference_type = typename __hashtable_base::difference_type;
00304 
00305       using iterator = typename __hashtable_base::iterator;
00306       using const_iterator = typename __hashtable_base::const_iterator;
00307 
00308       using local_iterator = typename __hashtable_base::local_iterator;
00309       using const_local_iterator = typename __hashtable_base::
00310                                    const_local_iterator;
00311 
00312     private:
00313       __bucket_type*            _M_buckets              = &_M_single_bucket;
00314       size_type                 _M_bucket_count         = 1;
00315       __node_base               _M_before_begin;
00316       size_type                 _M_element_count        = 0;
00317       _RehashPolicy             _M_rehash_policy;
00318 
00319       // A single bucket used when only need for 1 bucket. Especially
00320       // interesting in move semantic to leave hashtable with only 1 buckets
00321       // which is not allocated so that we can have those operations noexcept
00322       // qualified.
00323       // Note that we can't leave hashtable with 0 bucket without adding
00324       // numerous checks in the code to avoid 0 modulus.
00325       __bucket_type             _M_single_bucket        = nullptr;
00326 
00327       bool
00328       _M_uses_single_bucket(__bucket_type* __bkts) const
00329       { return __builtin_expect(__bkts == &_M_single_bucket, false); }
00330 
00331       bool
00332       _M_uses_single_bucket() const
00333       { return _M_uses_single_bucket(_M_buckets); }
00334 
00335       __hashtable_alloc&
00336       _M_base_alloc() { return *this; }
00337 
00338       __bucket_type*
00339       _M_allocate_buckets(size_type __n)
00340       {
00341         if (__builtin_expect(__n == 1, false))
00342           {
00343             _M_single_bucket = nullptr;
00344             return &_M_single_bucket;
00345           }
00346 
00347         return __hashtable_alloc::_M_allocate_buckets(__n);
00348       }
00349 
00350       void
00351       _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
00352       {
00353         if (_M_uses_single_bucket(__bkts))
00354           return;
00355 
00356         __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
00357       }
00358 
00359       void
00360       _M_deallocate_buckets()
00361       { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
00362 
00363       // Gets bucket begin, deals with the fact that non-empty buckets contain
00364       // their before begin node.
00365       __node_type*
00366       _M_bucket_begin(size_type __bkt) const;
00367 
00368       __node_type*
00369       _M_begin() const
00370       { return static_cast<__node_type*>(_M_before_begin._M_nxt); }
00371 
00372       template<typename _NodeGenerator>
00373         void
00374         _M_assign(const _Hashtable&, const _NodeGenerator&);
00375 
00376       void
00377       _M_move_assign(_Hashtable&&, std::true_type);
00378 
00379       void
00380       _M_move_assign(_Hashtable&&, std::false_type);
00381 
00382       void
00383       _M_reset() noexcept;
00384 
00385       _Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
00386                  const _Equal& __eq, const _ExtractKey& __exk,
00387                  const allocator_type& __a)
00388         : __hashtable_base(__exk, __h1, __h2, __h, __eq),
00389           __hashtable_alloc(__node_alloc_type(__a))
00390       { }
00391 
00392     public:
00393       // Constructor, destructor, assignment, swap
00394       _Hashtable() = default;
00395       _Hashtable(size_type __bucket_hint,
00396                  const _H1&, const _H2&, const _Hash&,
00397                  const _Equal&, const _ExtractKey&,
00398                  const allocator_type&);
00399 
00400       template<typename _InputIterator>
00401         _Hashtable(_InputIterator __first, _InputIterator __last,
00402                    size_type __bucket_hint,
00403                    const _H1&, const _H2&, const _Hash&,
00404                    const _Equal&, const _ExtractKey&,
00405                    const allocator_type&);
00406 
00407       _Hashtable(const _Hashtable&);
00408 
00409       _Hashtable(_Hashtable&&) noexcept;
00410 
00411       _Hashtable(const _Hashtable&, const allocator_type&);
00412 
00413       _Hashtable(_Hashtable&&, const allocator_type&);
00414 
00415       // Use delegating constructors.
00416       explicit
00417       _Hashtable(const allocator_type& __a)
00418         : __hashtable_alloc(__node_alloc_type(__a))
00419       { }
00420 
00421       explicit
00422       _Hashtable(size_type __n,
00423                  const _H1& __hf = _H1(),
00424                  const key_equal& __eql = key_equal(),
00425                  const allocator_type& __a = allocator_type())
00426       : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
00427                    __key_extract(), __a)
00428       { }
00429 
00430       template<typename _InputIterator>
00431         _Hashtable(_InputIterator __f, _InputIterator __l,
00432                    size_type __n = 0,
00433                    const _H1& __hf = _H1(),
00434                    const key_equal& __eql = key_equal(),
00435                    const allocator_type& __a = allocator_type())
00436         : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
00437                      __key_extract(), __a)
00438         { }
00439 
00440       _Hashtable(initializer_list<value_type> __l,
00441                  size_type __n = 0,
00442                  const _H1& __hf = _H1(),
00443                  const key_equal& __eql = key_equal(),
00444                  const allocator_type& __a = allocator_type())
00445       : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
00446                    __key_extract(), __a)
00447       { }
00448 
00449       _Hashtable&
00450       operator=(const _Hashtable& __ht);
00451 
00452       _Hashtable&
00453       operator=(_Hashtable&& __ht)
00454       noexcept(__node_alloc_traits::_S_nothrow_move())
00455       {
00456         constexpr bool __move_storage =
00457           __node_alloc_traits::_S_propagate_on_move_assign()
00458           || __node_alloc_traits::_S_always_equal();
00459         _M_move_assign(std::move(__ht),
00460                        integral_constant<bool, __move_storage>());
00461         return *this;
00462       }
00463 
00464       _Hashtable&
00465       operator=(initializer_list<value_type> __l)
00466       {
00467         __reuse_or_alloc_node_type __roan(_M_begin(), *this);
00468         _M_before_begin._M_nxt = nullptr;
00469         clear();
00470         this->_M_insert_range(__l.begin(), __l.end(), __roan);
00471         return *this;
00472       }
00473 
00474       ~_Hashtable() noexcept;
00475 
00476       void
00477       swap(_Hashtable&)
00478       noexcept(__node_alloc_traits::_S_nothrow_swap());
00479 
00480       // Basic container operations
00481       iterator
00482       begin() noexcept
00483       { return iterator(_M_begin()); }
00484 
00485       const_iterator
00486       begin() const noexcept
00487       { return const_iterator(_M_begin()); }
00488 
00489       iterator
00490       end() noexcept
00491       { return iterator(nullptr); }
00492 
00493       const_iterator
00494       end() const noexcept
00495       { return const_iterator(nullptr); }
00496 
00497       const_iterator
00498       cbegin() const noexcept
00499       { return const_iterator(_M_begin()); }
00500 
00501       const_iterator
00502       cend() const noexcept
00503       { return const_iterator(nullptr); }
00504 
00505       size_type
00506       size() const noexcept
00507       { return _M_element_count; }
00508 
00509       bool
00510       empty() const noexcept
00511       { return size() == 0; }
00512 
00513       allocator_type
00514       get_allocator() const noexcept
00515       { return allocator_type(this->_M_node_allocator()); }
00516 
00517       size_type
00518       max_size() const noexcept
00519       { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
00520 
00521       // Observers
00522       key_equal
00523       key_eq() const
00524       { return this->_M_eq(); }
00525 
00526       // hash_function, if present, comes from _Hash_code_base.
00527 
00528       // Bucket operations
00529       size_type
00530       bucket_count() const noexcept
00531       { return _M_bucket_count; }
00532 
00533       size_type
00534       max_bucket_count() const noexcept
00535       { return max_size(); }
00536 
00537       size_type
00538       bucket_size(size_type __n) const
00539       { return std::distance(begin(__n), end(__n)); }
00540 
00541       size_type
00542       bucket(const key_type& __k) const
00543       { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
00544 
00545       local_iterator
00546       begin(size_type __n)
00547       {
00548         return local_iterator(*this, _M_bucket_begin(__n),
00549                               __n, _M_bucket_count);
00550       }
00551 
00552       local_iterator
00553       end(size_type __n)
00554       { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
00555 
00556       const_local_iterator
00557       begin(size_type __n) const
00558       {
00559         return const_local_iterator(*this, _M_bucket_begin(__n),
00560                                     __n, _M_bucket_count);
00561       }
00562 
00563       const_local_iterator
00564       end(size_type __n) const
00565       { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
00566 
00567       // DR 691.
00568       const_local_iterator
00569       cbegin(size_type __n) const
00570       {
00571         return const_local_iterator(*this, _M_bucket_begin(__n),
00572                                     __n, _M_bucket_count);
00573       }
00574 
00575       const_local_iterator
00576       cend(size_type __n) const
00577       { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
00578 
00579       float
00580       load_factor() const noexcept
00581       {
00582         return static_cast<float>(size()) / static_cast<float>(bucket_count());
00583       }
00584 
00585       // max_load_factor, if present, comes from _Rehash_base.
00586 
00587       // Generalization of max_load_factor.  Extension, not found in
00588       // TR1.  Only useful if _RehashPolicy is something other than
00589       // the default.
00590       const _RehashPolicy&
00591       __rehash_policy() const
00592       { return _M_rehash_policy; }
00593 
00594       void
00595       __rehash_policy(const _RehashPolicy&);
00596 
00597       // Lookup.
00598       iterator
00599       find(const key_type& __k);
00600 
00601       const_iterator
00602       find(const key_type& __k) const;
00603 
00604       size_type
00605       count(const key_type& __k) const;
00606 
00607       std::pair<iterator, iterator>
00608       equal_range(const key_type& __k);
00609 
00610       std::pair<const_iterator, const_iterator>
00611       equal_range(const key_type& __k) const;
00612 
00613     protected:
00614       // Bucket index computation helpers.
00615       size_type
00616       _M_bucket_index(__node_type* __n) const noexcept
00617       { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
00618 
00619       size_type
00620       _M_bucket_index(const key_type& __k, __hash_code __c) const
00621       { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
00622 
00623       // Find and insert helper functions and types
00624       // Find the node before the one matching the criteria.
00625       __node_base*
00626       _M_find_before_node(size_type, const key_type&, __hash_code) const;
00627 
00628       __node_type*
00629       _M_find_node(size_type __bkt, const key_type& __key,
00630                    __hash_code __c) const
00631       {
00632         __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
00633         if (__before_n)
00634           return static_cast<__node_type*>(__before_n->_M_nxt);
00635         return nullptr;
00636       }
00637 
00638       // Insert a node at the beginning of a bucket.
00639       void
00640       _M_insert_bucket_begin(size_type, __node_type*);
00641 
00642       // Remove the bucket first node
00643       void
00644       _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
00645                              size_type __next_bkt);
00646 
00647       // Get the node before __n in the bucket __bkt
00648       __node_base*
00649       _M_get_previous_node(size_type __bkt, __node_base* __n);
00650 
00651       // Insert node with hash code __code, in bucket bkt if no rehash (assumes
00652       // no element with its key already present). Take ownership of the node,
00653       // deallocate it on exception.
00654       iterator
00655       _M_insert_unique_node(size_type __bkt, __hash_code __code,
00656                             __node_type* __n);
00657 
00658       // Insert node with hash code __code. Take ownership of the node,
00659       // deallocate it on exception.
00660       iterator
00661       _M_insert_multi_node(__node_type* __hint,
00662                            __hash_code __code, __node_type* __n);
00663 
00664       template<typename... _Args>
00665         std::pair<iterator, bool>
00666         _M_emplace(std::true_type, _Args&&... __args);
00667 
00668       template<typename... _Args>
00669         iterator
00670         _M_emplace(std::false_type __uk, _Args&&... __args)
00671         { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
00672 
00673       // Emplace with hint, useless when keys are unique.
00674       template<typename... _Args>
00675         iterator
00676         _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
00677         { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
00678 
00679       template<typename... _Args>
00680         iterator
00681         _M_emplace(const_iterator, std::false_type, _Args&&... __args);
00682 
00683       template<typename _Arg, typename _NodeGenerator>
00684         std::pair<iterator, bool>
00685         _M_insert(_Arg&&, const _NodeGenerator&, std::true_type);
00686 
00687       template<typename _Arg, typename _NodeGenerator>
00688         iterator
00689         _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
00690                   std::false_type __uk)
00691         {
00692           return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
00693                            __uk);
00694         }
00695 
00696       // Insert with hint, not used when keys are unique.
00697       template<typename _Arg, typename _NodeGenerator>
00698         iterator
00699         _M_insert(const_iterator, _Arg&& __arg,
00700                   const _NodeGenerator& __node_gen, std::true_type __uk)
00701         {
00702           return
00703             _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
00704         }
00705 
00706       // Insert with hint when keys are not unique.
00707       template<typename _Arg, typename _NodeGenerator>
00708         iterator
00709         _M_insert(const_iterator, _Arg&&,
00710                   const _NodeGenerator&, std::false_type);
00711 
00712       size_type
00713       _M_erase(std::true_type, const key_type&);
00714 
00715       size_type
00716       _M_erase(std::false_type, const key_type&);
00717 
00718       iterator
00719       _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
00720 
00721     public:
00722       // Emplace
00723       template<typename... _Args>
00724         __ireturn_type
00725         emplace(_Args&&... __args)
00726         { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
00727 
00728       template<typename... _Args>
00729         iterator
00730         emplace_hint(const_iterator __hint, _Args&&... __args)
00731         {
00732           return _M_emplace(__hint, __unique_keys(),
00733                             std::forward<_Args>(__args)...);
00734         }
00735 
00736       // Insert member functions via inheritance.
00737 
00738       // Erase
00739       iterator
00740       erase(const_iterator);
00741 
00742       // LWG 2059.
00743       iterator
00744       erase(iterator __it)
00745       { return erase(const_iterator(__it)); }
00746 
00747       size_type
00748       erase(const key_type& __k)
00749       { return _M_erase(__unique_keys(), __k); }
00750 
00751       iterator
00752       erase(const_iterator, const_iterator);
00753 
00754       void
00755       clear() noexcept;
00756 
00757       // Set number of buckets to be appropriate for container of n element.
00758       void rehash(size_type __n);
00759 
00760       // DR 1189.
00761       // reserve, if present, comes from _Rehash_base.
00762 
00763     private:
00764       // Helper rehash method used when keys are unique.
00765       void _M_rehash_aux(size_type __n, std::true_type);
00766 
00767       // Helper rehash method used when keys can be non-unique.
00768       void _M_rehash_aux(size_type __n, std::false_type);
00769 
00770       // Unconditionally change size of bucket array to n, restore
00771       // hash policy state to __state on exception.
00772       void _M_rehash(size_type __n, const __rehash_state& __state);
00773     };
00774 
00775 
00776   // Definitions of class template _Hashtable's out-of-line member functions.
00777   template<typename _Key, typename _Value,
00778            typename _Alloc, typename _ExtractKey, typename _Equal,
00779            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
00780            typename _Traits>
00781     auto
00782     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00783                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
00784     _M_bucket_begin(size_type __bkt) const
00785     -> __node_type*
00786     {
00787       __node_base* __n = _M_buckets[__bkt];
00788       return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
00789     }
00790 
00791   template<typename _Key, typename _Value,
00792            typename _Alloc, typename _ExtractKey, typename _Equal,
00793            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
00794            typename _Traits>
00795     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00796                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
00797     _Hashtable(size_type __bucket_hint,
00798                const _H1& __h1, const _H2& __h2, const _Hash& __h,
00799                const _Equal& __eq, const _ExtractKey& __exk,
00800                const allocator_type& __a)
00801       : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
00802     {
00803       auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
00804       if (__bkt > _M_bucket_count)
00805         {
00806           _M_buckets = _M_allocate_buckets(__bkt);
00807           _M_bucket_count = __bkt;
00808         }
00809     }
00810 
00811   template<typename _Key, typename _Value,
00812            typename _Alloc, typename _ExtractKey, typename _Equal,
00813            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
00814            typename _Traits>
00815     template<typename _InputIterator>
00816       _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00817                  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
00818       _Hashtable(_InputIterator __f, _InputIterator __l,
00819                  size_type __bucket_hint,
00820                  const _H1& __h1, const _H2& __h2, const _Hash& __h,
00821                  const _Equal& __eq, const _ExtractKey& __exk,
00822                  const allocator_type& __a)
00823         : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
00824       {
00825         auto __nb_elems = __detail::__distance_fw(__f, __l);
00826         auto __bkt_count =
00827           _M_rehash_policy._M_next_bkt(
00828             std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
00829                      __bucket_hint));
00830 
00831         if (__bkt_count > _M_bucket_count)
00832           {
00833             _M_buckets = _M_allocate_buckets(__bkt_count);
00834             _M_bucket_count = __bkt_count;
00835           }
00836 
00837         __try
00838           {
00839             for (; __f != __l; ++__f)
00840               this->insert(*__f);
00841           }
00842         __catch(...)
00843           {
00844             clear();
00845             _M_deallocate_buckets();
00846             __throw_exception_again;
00847           }
00848       }
00849 
00850   template<typename _Key, typename _Value,
00851            typename _Alloc, typename _ExtractKey, typename _Equal,
00852            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
00853            typename _Traits>
00854     auto
00855     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00856                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
00857     operator=(const _Hashtable& __ht)
00858     -> _Hashtable&
00859     {
00860       if (&__ht == this)
00861         return *this;
00862 
00863       if (__node_alloc_traits::_S_propagate_on_copy_assign())
00864         {
00865           auto& __this_alloc = this->_M_node_allocator();
00866           auto& __that_alloc = __ht._M_node_allocator();
00867           if (!__node_alloc_traits::_S_always_equal()
00868               && __this_alloc != __that_alloc)
00869             {
00870               // Replacement allocator cannot free existing storage.
00871               this->_M_deallocate_nodes(_M_begin());
00872               _M_before_begin._M_nxt = nullptr;
00873               _M_deallocate_buckets();
00874               _M_buckets = nullptr;
00875               std::__alloc_on_copy(__this_alloc, __that_alloc);
00876               __hashtable_base::operator=(__ht);
00877               _M_bucket_count = __ht._M_bucket_count;
00878               _M_element_count = __ht._M_element_count;
00879               _M_rehash_policy = __ht._M_rehash_policy;
00880               __try
00881                 {
00882                   _M_assign(__ht,
00883                             [this](const __node_type* __n)
00884                             { return this->_M_allocate_node(__n->_M_v()); });
00885                 }
00886               __catch(...)
00887                 {
00888                   // _M_assign took care of deallocating all memory. Now we
00889                   // must make sure this instance remains in a usable state.
00890                   _M_reset();
00891                   __throw_exception_again;
00892                 }
00893               return *this;
00894             }
00895           std::__alloc_on_copy(__this_alloc, __that_alloc);
00896         }
00897 
00898       // Reuse allocated buckets and nodes.
00899       __bucket_type* __former_buckets = nullptr;
00900       std::size_t __former_bucket_count = _M_bucket_count;
00901       const __rehash_state& __former_state = _M_rehash_policy._M_state();
00902 
00903       if (_M_bucket_count != __ht._M_bucket_count)
00904         {
00905           __former_buckets = _M_buckets;
00906           _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
00907           _M_bucket_count = __ht._M_bucket_count;
00908         }
00909       else
00910         __builtin_memset(_M_buckets, 0,
00911                          _M_bucket_count * sizeof(__bucket_type));
00912 
00913       __try
00914         {
00915           __hashtable_base::operator=(__ht);
00916           _M_element_count = __ht._M_element_count;
00917           _M_rehash_policy = __ht._M_rehash_policy;
00918           __reuse_or_alloc_node_type __roan(_M_begin(), *this);
00919           _M_before_begin._M_nxt = nullptr;
00920           _M_assign(__ht,
00921                     [&__roan](const __node_type* __n)
00922                     { return __roan(__n->_M_v()); });
00923           if (__former_buckets)
00924             _M_deallocate_buckets(__former_buckets, __former_bucket_count);
00925         }
00926       __catch(...)
00927         {
00928           if (__former_buckets)
00929             {
00930               // Restore previous buckets.
00931               _M_deallocate_buckets();
00932               _M_rehash_policy._M_reset(__former_state);
00933               _M_buckets = __former_buckets;
00934               _M_bucket_count = __former_bucket_count;
00935             }
00936           __builtin_memset(_M_buckets, 0,
00937                            _M_bucket_count * sizeof(__bucket_type));
00938           __throw_exception_again;
00939         }
00940       return *this;
00941     }
00942 
00943   template<typename _Key, typename _Value,
00944            typename _Alloc, typename _ExtractKey, typename _Equal,
00945            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
00946            typename _Traits>
00947     template<typename _NodeGenerator>
00948       void
00949       _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00950                  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
00951       _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
00952       {
00953         __bucket_type* __buckets = nullptr;
00954         if (!_M_buckets)
00955           _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
00956 
00957         __try
00958           {
00959             if (!__ht._M_before_begin._M_nxt)
00960               return;
00961 
00962             // First deal with the special first node pointed to by
00963             // _M_before_begin.
00964             __node_type* __ht_n = __ht._M_begin();
00965             __node_type* __this_n = __node_gen(__ht_n);
00966             this->_M_copy_code(__this_n, __ht_n);
00967             _M_before_begin._M_nxt = __this_n;
00968             _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
00969 
00970             // Then deal with other nodes.
00971             __node_base* __prev_n = __this_n;
00972             for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
00973               {
00974                 __this_n = __node_gen(__ht_n);
00975                 __prev_n->_M_nxt = __this_n;
00976                 this->_M_copy_code(__this_n, __ht_n);
00977                 size_type __bkt = _M_bucket_index(__this_n);
00978                 if (!_M_buckets[__bkt])
00979                   _M_buckets[__bkt] = __prev_n;
00980                 __prev_n = __this_n;
00981               }
00982           }
00983         __catch(...)
00984           {
00985             clear();
00986             if (__buckets)
00987               _M_deallocate_buckets();
00988             __throw_exception_again;
00989           }
00990       }
00991 
00992   template<typename _Key, typename _Value,
00993            typename _Alloc, typename _ExtractKey, typename _Equal,
00994            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
00995            typename _Traits>
00996     void
00997     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00998                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
00999     _M_reset() noexcept
01000     {
01001       _M_rehash_policy._M_reset();
01002       _M_bucket_count = 1;
01003       _M_single_bucket = nullptr;
01004       _M_buckets = &_M_single_bucket;
01005       _M_before_begin._M_nxt = nullptr;
01006       _M_element_count = 0;
01007     }
01008 
01009   template<typename _Key, typename _Value,
01010            typename _Alloc, typename _ExtractKey, typename _Equal,
01011            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01012            typename _Traits>
01013     void
01014     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01015                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01016     _M_move_assign(_Hashtable&& __ht, std::true_type)
01017     {
01018       this->_M_deallocate_nodes(_M_begin());
01019       _M_deallocate_buckets();
01020       __hashtable_base::operator=(std::move(__ht));
01021       _M_rehash_policy = __ht._M_rehash_policy;
01022       if (!__ht._M_uses_single_bucket())
01023         _M_buckets = __ht._M_buckets;
01024       else
01025         {
01026           _M_buckets = &_M_single_bucket;
01027           _M_single_bucket = __ht._M_single_bucket;
01028         }
01029       _M_bucket_count = __ht._M_bucket_count;
01030       _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
01031       _M_element_count = __ht._M_element_count;
01032       std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
01033 
01034       // Fix buckets containing the _M_before_begin pointers that can't be
01035       // moved.
01036       if (_M_begin())
01037         _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
01038       __ht._M_reset();
01039     }
01040 
01041   template<typename _Key, typename _Value,
01042            typename _Alloc, typename _ExtractKey, typename _Equal,
01043            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01044            typename _Traits>
01045     void
01046     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01047                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01048     _M_move_assign(_Hashtable&& __ht, std::false_type)
01049     {
01050       if (__ht._M_node_allocator() == this->_M_node_allocator())
01051         _M_move_assign(std::move(__ht), std::true_type());
01052       else
01053         {
01054           // Can't move memory, move elements then.
01055           __bucket_type* __former_buckets = nullptr;
01056           size_type __former_bucket_count = _M_bucket_count;
01057           const __rehash_state& __former_state = _M_rehash_policy._M_state();
01058 
01059           if (_M_bucket_count != __ht._M_bucket_count)
01060             {
01061               __former_buckets = _M_buckets;
01062               _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
01063               _M_bucket_count = __ht._M_bucket_count;
01064             }
01065           else
01066             __builtin_memset(_M_buckets, 0,
01067                              _M_bucket_count * sizeof(__bucket_type));
01068 
01069           __try
01070             {
01071               __hashtable_base::operator=(std::move(__ht));
01072               _M_element_count = __ht._M_element_count;
01073               _M_rehash_policy = __ht._M_rehash_policy;
01074               __reuse_or_alloc_node_type __roan(_M_begin(), *this);
01075               _M_before_begin._M_nxt = nullptr;
01076               _M_assign(__ht,
01077                         [&__roan](__node_type* __n)
01078                         { return __roan(std::move_if_noexcept(__n->_M_v())); });
01079               __ht.clear();
01080             }
01081           __catch(...)
01082             {
01083               if (__former_buckets)
01084                 {
01085                   _M_deallocate_buckets();
01086                   _M_rehash_policy._M_reset(__former_state);
01087                   _M_buckets = __former_buckets;
01088                   _M_bucket_count = __former_bucket_count;
01089                 }
01090               __builtin_memset(_M_buckets, 0,
01091                                _M_bucket_count * sizeof(__bucket_type));
01092               __throw_exception_again;
01093             }
01094         }
01095     }
01096 
01097   template<typename _Key, typename _Value,
01098            typename _Alloc, typename _ExtractKey, typename _Equal,
01099            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01100            typename _Traits>
01101     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01102                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01103     _Hashtable(const _Hashtable& __ht)
01104     : __hashtable_base(__ht),
01105       __map_base(__ht),
01106       __rehash_base(__ht),
01107       __hashtable_alloc(
01108         __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
01109       _M_buckets(nullptr),
01110       _M_bucket_count(__ht._M_bucket_count),
01111       _M_element_count(__ht._M_element_count),
01112       _M_rehash_policy(__ht._M_rehash_policy)
01113     {
01114       _M_assign(__ht,
01115                 [this](const __node_type* __n)
01116                 { return this->_M_allocate_node(__n->_M_v()); });
01117     }
01118 
01119   template<typename _Key, typename _Value,
01120            typename _Alloc, typename _ExtractKey, typename _Equal,
01121            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01122            typename _Traits>
01123     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01124                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01125     _Hashtable(_Hashtable&& __ht) noexcept
01126     : __hashtable_base(__ht),
01127       __map_base(__ht),
01128       __rehash_base(__ht),
01129       __hashtable_alloc(std::move(__ht._M_base_alloc())),
01130       _M_buckets(__ht._M_buckets),
01131       _M_bucket_count(__ht._M_bucket_count),
01132       _M_before_begin(__ht._M_before_begin._M_nxt),
01133       _M_element_count(__ht._M_element_count),
01134       _M_rehash_policy(__ht._M_rehash_policy)
01135     {
01136       // Update, if necessary, buckets if __ht is using its single bucket.
01137       if (__ht._M_uses_single_bucket())
01138         {
01139           _M_buckets = &_M_single_bucket;
01140           _M_single_bucket = __ht._M_single_bucket;
01141         }
01142 
01143       // Update, if necessary, bucket pointing to before begin that hasn't
01144       // moved.
01145       if (_M_begin())
01146         _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
01147 
01148       __ht._M_reset();
01149     }
01150 
01151   template<typename _Key, typename _Value,
01152            typename _Alloc, typename _ExtractKey, typename _Equal,
01153            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01154            typename _Traits>
01155     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01156                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01157     _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
01158     : __hashtable_base(__ht),
01159       __map_base(__ht),
01160       __rehash_base(__ht),
01161       __hashtable_alloc(__node_alloc_type(__a)),
01162       _M_buckets(),
01163       _M_bucket_count(__ht._M_bucket_count),
01164       _M_element_count(__ht._M_element_count),
01165       _M_rehash_policy(__ht._M_rehash_policy)
01166     {
01167       _M_assign(__ht,
01168                 [this](const __node_type* __n)
01169                 { return this->_M_allocate_node(__n->_M_v()); });
01170     }
01171 
01172   template<typename _Key, typename _Value,
01173            typename _Alloc, typename _ExtractKey, typename _Equal,
01174            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01175            typename _Traits>
01176     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01177                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01178     _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
01179     : __hashtable_base(__ht),
01180       __map_base(__ht),
01181       __rehash_base(__ht),
01182       __hashtable_alloc(__node_alloc_type(__a)),
01183       _M_buckets(nullptr),
01184       _M_bucket_count(__ht._M_bucket_count),
01185       _M_element_count(__ht._M_element_count),
01186       _M_rehash_policy(__ht._M_rehash_policy)
01187     {
01188       if (__ht._M_node_allocator() == this->_M_node_allocator())
01189         {
01190           if (__ht._M_uses_single_bucket())
01191             {
01192               _M_buckets = &_M_single_bucket;
01193               _M_single_bucket = __ht._M_single_bucket;
01194             }
01195           else
01196             _M_buckets = __ht._M_buckets;
01197 
01198           _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
01199           // Update, if necessary, bucket pointing to before begin that hasn't
01200           // moved.
01201           if (_M_begin())
01202             _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
01203           __ht._M_reset();
01204         }
01205       else
01206         {
01207           _M_assign(__ht,
01208                     [this](__node_type* __n)
01209                     {
01210                       return this->_M_allocate_node(
01211                                         std::move_if_noexcept(__n->_M_v()));
01212                     });
01213           __ht.clear();
01214         }
01215     }
01216 
01217   template<typename _Key, typename _Value,
01218            typename _Alloc, typename _ExtractKey, typename _Equal,
01219            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01220            typename _Traits>
01221     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01222                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01223     ~_Hashtable() noexcept
01224     {
01225       clear();
01226       _M_deallocate_buckets();
01227     }
01228 
01229   template<typename _Key, typename _Value,
01230            typename _Alloc, typename _ExtractKey, typename _Equal,
01231            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01232            typename _Traits>
01233     void
01234     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01235                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01236     swap(_Hashtable& __x)
01237     noexcept(__node_alloc_traits::_S_nothrow_swap())
01238     {
01239       // The only base class with member variables is hash_code_base.
01240       // We define _Hash_code_base::_M_swap because different
01241       // specializations have different members.
01242       this->_M_swap(__x);
01243 
01244       std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
01245       std::swap(_M_rehash_policy, __x._M_rehash_policy);
01246 
01247       // Deal properly with potentially moved instances.
01248       if (this->_M_uses_single_bucket())
01249         {
01250           if (!__x._M_uses_single_bucket())
01251             {
01252               _M_buckets = __x._M_buckets;
01253               __x._M_buckets = &__x._M_single_bucket;
01254             }
01255         }
01256       else if (__x._M_uses_single_bucket())
01257         {
01258           __x._M_buckets = _M_buckets;
01259           _M_buckets = &_M_single_bucket;
01260         }       
01261       else
01262         std::swap(_M_buckets, __x._M_buckets);
01263 
01264       std::swap(_M_bucket_count, __x._M_bucket_count);
01265       std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
01266       std::swap(_M_element_count, __x._M_element_count);
01267       std::swap(_M_single_bucket, __x._M_single_bucket);
01268 
01269       // Fix buckets containing the _M_before_begin pointers that can't be
01270       // swapped.
01271       if (_M_begin())
01272         _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
01273 
01274       if (__x._M_begin())
01275         __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
01276           = &__x._M_before_begin;
01277     }
01278 
01279   template<typename _Key, typename _Value,
01280            typename _Alloc, typename _ExtractKey, typename _Equal,
01281            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01282            typename _Traits>
01283     void
01284     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01285                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01286     __rehash_policy(const _RehashPolicy& __pol)
01287     {
01288       auto __do_rehash =
01289         __pol._M_need_rehash(_M_bucket_count, _M_element_count, 0);
01290       if (__do_rehash.first)
01291         _M_rehash(__do_rehash.second, _M_rehash_policy._M_state());
01292       _M_rehash_policy = __pol;
01293     }
01294 
01295   template<typename _Key, typename _Value,
01296            typename _Alloc, typename _ExtractKey, typename _Equal,
01297            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01298            typename _Traits>
01299     auto
01300     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01301                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01302     find(const key_type& __k)
01303     -> iterator
01304     {
01305       __hash_code __code = this->_M_hash_code(__k);
01306       std::size_t __n = _M_bucket_index(__k, __code);
01307       __node_type* __p = _M_find_node(__n, __k, __code);
01308       return __p ? iterator(__p) : end();
01309     }
01310 
01311   template<typename _Key, typename _Value,
01312            typename _Alloc, typename _ExtractKey, typename _Equal,
01313            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01314            typename _Traits>
01315     auto
01316     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01317                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01318     find(const key_type& __k) const
01319     -> const_iterator
01320     {
01321       __hash_code __code = this->_M_hash_code(__k);
01322       std::size_t __n = _M_bucket_index(__k, __code);
01323       __node_type* __p = _M_find_node(__n, __k, __code);
01324       return __p ? const_iterator(__p) : end();
01325     }
01326 
01327   template<typename _Key, typename _Value,
01328            typename _Alloc, typename _ExtractKey, typename _Equal,
01329            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01330            typename _Traits>
01331     auto
01332     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01333                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01334     count(const key_type& __k) const
01335     -> size_type
01336     {
01337       __hash_code __code = this->_M_hash_code(__k);
01338       std::size_t __n = _M_bucket_index(__k, __code);
01339       __node_type* __p = _M_bucket_begin(__n);
01340       if (!__p)
01341         return 0;
01342 
01343       std::size_t __result = 0;
01344       for (;; __p = __p->_M_next())
01345         {
01346           if (this->_M_equals(__k, __code, __p))
01347             ++__result;
01348           else if (__result)
01349             // All equivalent values are next to each other, if we
01350             // found a non-equivalent value after an equivalent one it
01351             // means that we won't find any new equivalent value.
01352             break;
01353           if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
01354             break;
01355         }
01356       return __result;
01357     }
01358 
01359   template<typename _Key, typename _Value,
01360            typename _Alloc, typename _ExtractKey, typename _Equal,
01361            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01362            typename _Traits>
01363     auto
01364     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01365                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01366     equal_range(const key_type& __k)
01367     -> pair<iterator, iterator>
01368     {
01369       __hash_code __code = this->_M_hash_code(__k);
01370       std::size_t __n = _M_bucket_index(__k, __code);
01371       __node_type* __p = _M_find_node(__n, __k, __code);
01372 
01373       if (__p)
01374         {
01375           __node_type* __p1 = __p->_M_next();
01376           while (__p1 && _M_bucket_index(__p1) == __n
01377                  && this->_M_equals(__k, __code, __p1))
01378             __p1 = __p1->_M_next();
01379 
01380           return std::make_pair(iterator(__p), iterator(__p1));
01381         }
01382       else
01383         return std::make_pair(end(), end());
01384     }
01385 
01386   template<typename _Key, typename _Value,
01387            typename _Alloc, typename _ExtractKey, typename _Equal,
01388            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01389            typename _Traits>
01390     auto
01391     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01392                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01393     equal_range(const key_type& __k) const
01394     -> pair<const_iterator, const_iterator>
01395     {
01396       __hash_code __code = this->_M_hash_code(__k);
01397       std::size_t __n = _M_bucket_index(__k, __code);
01398       __node_type* __p = _M_find_node(__n, __k, __code);
01399 
01400       if (__p)
01401         {
01402           __node_type* __p1 = __p->_M_next();
01403           while (__p1 && _M_bucket_index(__p1) == __n
01404                  && this->_M_equals(__k, __code, __p1))
01405             __p1 = __p1->_M_next();
01406 
01407           return std::make_pair(const_iterator(__p), const_iterator(__p1));
01408         }
01409       else
01410         return std::make_pair(end(), end());
01411     }
01412 
01413   // Find the node whose key compares equal to k in the bucket n.
01414   // Return nullptr if no node is found.
01415   template<typename _Key, typename _Value,
01416            typename _Alloc, typename _ExtractKey, typename _Equal,
01417            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01418            typename _Traits>
01419     auto
01420     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01421                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01422     _M_find_before_node(size_type __n, const key_type& __k,
01423                         __hash_code __code) const
01424     -> __node_base*
01425     {
01426       __node_base* __prev_p = _M_buckets[__n];
01427       if (!__prev_p)
01428         return nullptr;
01429 
01430       for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
01431            __p = __p->_M_next())
01432         {
01433           if (this->_M_equals(__k, __code, __p))
01434             return __prev_p;
01435 
01436           if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
01437             break;
01438           __prev_p = __p;
01439         }
01440       return nullptr;
01441     }
01442 
01443   template<typename _Key, typename _Value,
01444            typename _Alloc, typename _ExtractKey, typename _Equal,
01445            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01446            typename _Traits>
01447     void
01448     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01449                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01450     _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
01451     {
01452       if (_M_buckets[__bkt])
01453         {
01454           // Bucket is not empty, we just need to insert the new node
01455           // after the bucket before begin.
01456           __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
01457           _M_buckets[__bkt]->_M_nxt = __node;
01458         }
01459       else
01460         {
01461           // The bucket is empty, the new node is inserted at the
01462           // beginning of the singly-linked list and the bucket will
01463           // contain _M_before_begin pointer.
01464           __node->_M_nxt = _M_before_begin._M_nxt;
01465           _M_before_begin._M_nxt = __node;
01466           if (__node->_M_nxt)
01467             // We must update former begin bucket that is pointing to
01468             // _M_before_begin.
01469             _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
01470           _M_buckets[__bkt] = &_M_before_begin;
01471         }
01472     }
01473 
01474   template<typename _Key, typename _Value,
01475            typename _Alloc, typename _ExtractKey, typename _Equal,
01476            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01477            typename _Traits>
01478     void
01479     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01480                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01481     _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
01482                            size_type __next_bkt)
01483     {
01484       if (!__next || __next_bkt != __bkt)
01485         {
01486           // Bucket is now empty
01487           // First update next bucket if any
01488           if (__next)
01489             _M_buckets[__next_bkt] = _M_buckets[__bkt];
01490 
01491           // Second update before begin node if necessary
01492           if (&_M_before_begin == _M_buckets[__bkt])
01493             _M_before_begin._M_nxt = __next;
01494           _M_buckets[__bkt] = nullptr;
01495         }
01496     }
01497 
01498   template<typename _Key, typename _Value,
01499            typename _Alloc, typename _ExtractKey, typename _Equal,
01500            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01501            typename _Traits>
01502     auto
01503     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01504                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01505     _M_get_previous_node(size_type __bkt, __node_base* __n)
01506     -> __node_base*
01507     {
01508       __node_base* __prev_n = _M_buckets[__bkt];
01509       while (__prev_n->_M_nxt != __n)
01510         __prev_n = __prev_n->_M_nxt;
01511       return __prev_n;
01512     }
01513 
01514   template<typename _Key, typename _Value,
01515            typename _Alloc, typename _ExtractKey, typename _Equal,
01516            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01517            typename _Traits>
01518     template<typename... _Args>
01519       auto
01520       _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01521                  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01522       _M_emplace(std::true_type, _Args&&... __args)
01523       -> pair<iterator, bool>
01524       {
01525         // First build the node to get access to the hash code
01526         __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
01527         const key_type& __k = this->_M_extract()(__node->_M_v());
01528         __hash_code __code;
01529         __try
01530           {
01531             __code = this->_M_hash_code(__k);
01532           }
01533         __catch(...)
01534           {
01535             this->_M_deallocate_node(__node);
01536             __throw_exception_again;
01537           }
01538 
01539         size_type __bkt = _M_bucket_index(__k, __code);
01540         if (__node_type* __p = _M_find_node(__bkt, __k, __code))
01541           {
01542             // There is already an equivalent node, no insertion
01543             this->_M_deallocate_node(__node);
01544             return std::make_pair(iterator(__p), false);
01545           }
01546 
01547         // Insert the node
01548         return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
01549                               true);
01550       }
01551 
01552   template<typename _Key, typename _Value,
01553            typename _Alloc, typename _ExtractKey, typename _Equal,
01554            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01555            typename _Traits>
01556     template<typename... _Args>
01557       auto
01558       _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01559                  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01560       _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
01561       -> iterator
01562       {
01563         // First build the node to get its hash code.
01564         __node_type* __node =
01565           this->_M_allocate_node(std::forward<_Args>(__args)...);
01566 
01567         __hash_code __code;
01568         __try
01569           {
01570             __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
01571           }
01572         __catch(...)
01573           {
01574             this->_M_deallocate_node(__node);
01575             __throw_exception_again;
01576           }
01577 
01578         return _M_insert_multi_node(__hint._M_cur, __code, __node);
01579       }
01580 
01581   template<typename _Key, typename _Value,
01582            typename _Alloc, typename _ExtractKey, typename _Equal,
01583            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01584            typename _Traits>
01585     auto
01586     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01587                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01588     _M_insert_unique_node(size_type __bkt, __hash_code __code,
01589                           __node_type* __node)
01590     -> iterator
01591     {
01592       const __rehash_state& __saved_state = _M_rehash_policy._M_state();
01593       std::pair<bool, std::size_t> __do_rehash
01594         = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
01595 
01596       __try
01597         {
01598           if (__do_rehash.first)
01599             {
01600               _M_rehash(__do_rehash.second, __saved_state);
01601               __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
01602             }
01603 
01604           this->_M_store_code(__node, __code);
01605 
01606           // Always insert at the beginning of the bucket.
01607           _M_insert_bucket_begin(__bkt, __node);
01608           ++_M_element_count;
01609           return iterator(__node);
01610         }
01611       __catch(...)
01612         {
01613           this->_M_deallocate_node(__node);
01614           __throw_exception_again;
01615         }
01616     }
01617 
01618   // Insert node, in bucket bkt if no rehash (assumes no element with its key
01619   // already present). Take ownership of the node, deallocate it on exception.
01620   template<typename _Key, typename _Value,
01621            typename _Alloc, typename _ExtractKey, typename _Equal,
01622            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01623            typename _Traits>
01624     auto
01625     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01626                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01627     _M_insert_multi_node(__node_type* __hint, __hash_code __code,
01628                          __node_type* __node)
01629     -> iterator
01630     {
01631       const __rehash_state& __saved_state = _M_rehash_policy._M_state();
01632       std::pair<bool, std::size_t> __do_rehash
01633         = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
01634 
01635       __try
01636         {
01637           if (__do_rehash.first)
01638             _M_rehash(__do_rehash.second, __saved_state);
01639 
01640           this->_M_store_code(__node, __code);
01641           const key_type& __k = this->_M_extract()(__node->_M_v());
01642           size_type __bkt = _M_bucket_index(__k, __code);
01643 
01644           // Find the node before an equivalent one or use hint if it exists and
01645           // if it is equivalent.
01646           __node_base* __prev
01647             = __builtin_expect(__hint != nullptr, false)
01648               && this->_M_equals(__k, __code, __hint)
01649                 ? __hint
01650                 : _M_find_before_node(__bkt, __k, __code);
01651           if (__prev)
01652             {
01653               // Insert after the node before the equivalent one.
01654               __node->_M_nxt = __prev->_M_nxt;
01655               __prev->_M_nxt = __node;
01656               if (__builtin_expect(__prev == __hint, false))
01657                 // hint might be the last bucket node, in this case we need to
01658                 // update next bucket.
01659                 if (__node->_M_nxt
01660                     && !this->_M_equals(__k, __code, __node->_M_next()))
01661                   {
01662                     size_type __next_bkt = _M_bucket_index(__node->_M_next());
01663                     if (__next_bkt != __bkt)
01664                       _M_buckets[__next_bkt] = __node;
01665                   }
01666             }
01667           else
01668             // The inserted node has no equivalent in the
01669             // hashtable. We must insert the new node at the
01670             // beginning of the bucket to preserve equivalent
01671             // elements' relative positions.
01672             _M_insert_bucket_begin(__bkt, __node);
01673           ++_M_element_count;
01674           return iterator(__node);
01675         }
01676       __catch(...)
01677         {
01678           this->_M_deallocate_node(__node);
01679           __throw_exception_again;
01680         }
01681     }
01682 
01683   // Insert v if no element with its key is already present.
01684   template<typename _Key, typename _Value,
01685            typename _Alloc, typename _ExtractKey, typename _Equal,
01686            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01687            typename _Traits>
01688     template<typename _Arg, typename _NodeGenerator>
01689       auto
01690       _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01691                  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01692       _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, std::true_type)
01693       -> pair<iterator, bool>
01694       {
01695         const key_type& __k = this->_M_extract()(__v);
01696         __hash_code __code = this->_M_hash_code(__k);
01697         size_type __bkt = _M_bucket_index(__k, __code);
01698 
01699         __node_type* __n = _M_find_node(__bkt, __k, __code);
01700         if (__n)
01701           return std::make_pair(iterator(__n), false);
01702 
01703         __n = __node_gen(std::forward<_Arg>(__v));
01704         return std::make_pair(_M_insert_unique_node(__bkt, __code, __n), true);
01705       }
01706 
01707   // Insert v unconditionally.
01708   template<typename _Key, typename _Value,
01709            typename _Alloc, typename _ExtractKey, typename _Equal,
01710            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01711            typename _Traits>
01712     template<typename _Arg, typename _NodeGenerator>
01713       auto
01714       _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01715                  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01716       _M_insert(const_iterator __hint, _Arg&& __v,
01717                 const _NodeGenerator& __node_gen, std::false_type)
01718       -> iterator
01719       {
01720         // First compute the hash code so that we don't do anything if it
01721         // throws.
01722         __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
01723 
01724         // Second allocate new node so that we don't rehash if it throws.
01725         __node_type* __node = __node_gen(std::forward<_Arg>(__v));
01726 
01727         return _M_insert_multi_node(__hint._M_cur, __code, __node);
01728       }
01729 
01730   template<typename _Key, typename _Value,
01731            typename _Alloc, typename _ExtractKey, typename _Equal,
01732            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01733            typename _Traits>
01734     auto
01735     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01736                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01737     erase(const_iterator __it)
01738     -> iterator
01739     {
01740       __node_type* __n = __it._M_cur;
01741       std::size_t __bkt = _M_bucket_index(__n);
01742 
01743       // Look for previous node to unlink it from the erased one, this
01744       // is why we need buckets to contain the before begin to make
01745       // this search fast.
01746       __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
01747       return _M_erase(__bkt, __prev_n, __n);
01748     }
01749 
01750   template<typename _Key, typename _Value,
01751            typename _Alloc, typename _ExtractKey, typename _Equal,
01752            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01753            typename _Traits>
01754     auto
01755     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01756                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01757     _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
01758     -> iterator
01759     {
01760       if (__prev_n == _M_buckets[__bkt])
01761         _M_remove_bucket_begin(__bkt, __n->_M_next(),
01762            __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
01763       else if (__n->_M_nxt)
01764         {
01765           size_type __next_bkt = _M_bucket_index(__n->_M_next());
01766           if (__next_bkt != __bkt)
01767             _M_buckets[__next_bkt] = __prev_n;
01768         }
01769 
01770       __prev_n->_M_nxt = __n->_M_nxt;
01771       iterator __result(__n->_M_next());
01772       this->_M_deallocate_node(__n);
01773       --_M_element_count;
01774 
01775       return __result;
01776     }
01777 
01778   template<typename _Key, typename _Value,
01779            typename _Alloc, typename _ExtractKey, typename _Equal,
01780            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01781            typename _Traits>
01782     auto
01783     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01784                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01785     _M_erase(std::true_type, const key_type& __k)
01786     -> size_type
01787     {
01788       __hash_code __code = this->_M_hash_code(__k);
01789       std::size_t __bkt = _M_bucket_index(__k, __code);
01790 
01791       // Look for the node before the first matching node.
01792       __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
01793       if (!__prev_n)
01794         return 0;
01795 
01796       // We found a matching node, erase it.
01797       __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
01798       _M_erase(__bkt, __prev_n, __n);
01799       return 1;
01800     }
01801 
01802   template<typename _Key, typename _Value,
01803            typename _Alloc, typename _ExtractKey, typename _Equal,
01804            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01805            typename _Traits>
01806     auto
01807     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01808                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01809     _M_erase(std::false_type, const key_type& __k)
01810     -> size_type
01811     {
01812       __hash_code __code = this->_M_hash_code(__k);
01813       std::size_t __bkt = _M_bucket_index(__k, __code);
01814 
01815       // Look for the node before the first matching node.
01816       __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
01817       if (!__prev_n)
01818         return 0;
01819 
01820       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01821       // 526. Is it undefined if a function in the standard changes
01822       // in parameters?
01823       // We use one loop to find all matching nodes and another to deallocate
01824       // them so that the key stays valid during the first loop. It might be
01825       // invalidated indirectly when destroying nodes.
01826       __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
01827       __node_type* __n_last = __n;
01828       std::size_t __n_last_bkt = __bkt;
01829       do
01830         {
01831           __n_last = __n_last->_M_next();
01832           if (!__n_last)
01833             break;
01834           __n_last_bkt = _M_bucket_index(__n_last);
01835         }
01836       while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
01837 
01838       // Deallocate nodes.
01839       size_type __result = 0;
01840       do
01841         {
01842           __node_type* __p = __n->_M_next();
01843           this->_M_deallocate_node(__n);
01844           __n = __p;
01845           ++__result;
01846           --_M_element_count;
01847         }
01848       while (__n != __n_last);
01849 
01850       if (__prev_n == _M_buckets[__bkt])
01851         _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
01852       else if (__n_last && __n_last_bkt != __bkt)
01853         _M_buckets[__n_last_bkt] = __prev_n;
01854       __prev_n->_M_nxt = __n_last;
01855       return __result;
01856     }
01857 
01858   template<typename _Key, typename _Value,
01859            typename _Alloc, typename _ExtractKey, typename _Equal,
01860            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01861            typename _Traits>
01862     auto
01863     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01864                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01865     erase(const_iterator __first, const_iterator __last)
01866     -> iterator
01867     {
01868       __node_type* __n = __first._M_cur;
01869       __node_type* __last_n = __last._M_cur;
01870       if (__n == __last_n)
01871         return iterator(__n);
01872 
01873       std::size_t __bkt = _M_bucket_index(__n);
01874 
01875       __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
01876       bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
01877       std::size_t __n_bkt = __bkt;
01878       for (;;)
01879         {
01880           do
01881             {
01882               __node_type* __tmp = __n;
01883               __n = __n->_M_next();
01884               this->_M_deallocate_node(__tmp);
01885               --_M_element_count;
01886               if (!__n)
01887                 break;
01888               __n_bkt = _M_bucket_index(__n);
01889             }
01890           while (__n != __last_n && __n_bkt == __bkt);
01891           if (__is_bucket_begin)
01892             _M_remove_bucket_begin(__bkt, __n, __n_bkt);
01893           if (__n == __last_n)
01894             break;
01895           __is_bucket_begin = true;
01896           __bkt = __n_bkt;
01897         }
01898 
01899       if (__n && (__n_bkt != __bkt || __is_bucket_begin))
01900         _M_buckets[__n_bkt] = __prev_n;
01901       __prev_n->_M_nxt = __n;
01902       return iterator(__n);
01903     }
01904 
01905   template<typename _Key, typename _Value,
01906            typename _Alloc, typename _ExtractKey, typename _Equal,
01907            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01908            typename _Traits>
01909     void
01910     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01911                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01912     clear() noexcept
01913     {
01914       this->_M_deallocate_nodes(_M_begin());
01915       __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
01916       _M_element_count = 0;
01917       _M_before_begin._M_nxt = nullptr;
01918     }
01919 
01920   template<typename _Key, typename _Value,
01921            typename _Alloc, typename _ExtractKey, typename _Equal,
01922            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01923            typename _Traits>
01924     void
01925     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01926                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01927     rehash(size_type __n)
01928     {
01929       const __rehash_state& __saved_state = _M_rehash_policy._M_state();
01930       std::size_t __buckets
01931         = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
01932                    __n);
01933       __buckets = _M_rehash_policy._M_next_bkt(__buckets);
01934 
01935       if (__buckets != _M_bucket_count)
01936         _M_rehash(__buckets, __saved_state);
01937       else
01938         // No rehash, restore previous state to keep a consistent state.
01939         _M_rehash_policy._M_reset(__saved_state);
01940     }
01941 
01942   template<typename _Key, typename _Value,
01943            typename _Alloc, typename _ExtractKey, typename _Equal,
01944            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01945            typename _Traits>
01946     void
01947     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01948                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01949     _M_rehash(size_type __n, const __rehash_state& __state)
01950     {
01951       __try
01952         {
01953           _M_rehash_aux(__n, __unique_keys());
01954         }
01955       __catch(...)
01956         {
01957           // A failure here means that buckets allocation failed.  We only
01958           // have to restore hash policy previous state.
01959           _M_rehash_policy._M_reset(__state);
01960           __throw_exception_again;
01961         }
01962     }
01963 
01964   // Rehash when there is no equivalent elements.
01965   template<typename _Key, typename _Value,
01966            typename _Alloc, typename _ExtractKey, typename _Equal,
01967            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
01968            typename _Traits>
01969     void
01970     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01971                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
01972     _M_rehash_aux(size_type __n, std::true_type)
01973     {
01974       __bucket_type* __new_buckets = _M_allocate_buckets(__n);
01975       __node_type* __p = _M_begin();
01976       _M_before_begin._M_nxt = nullptr;
01977       std::size_t __bbegin_bkt = 0;
01978       while (__p)
01979         {
01980           __node_type* __next = __p->_M_next();
01981           std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
01982           if (!__new_buckets[__bkt])
01983             {
01984               __p->_M_nxt = _M_before_begin._M_nxt;
01985               _M_before_begin._M_nxt = __p;
01986               __new_buckets[__bkt] = &_M_before_begin;
01987               if (__p->_M_nxt)
01988                 __new_buckets[__bbegin_bkt] = __p;
01989               __bbegin_bkt = __bkt;
01990             }
01991           else
01992             {
01993               __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
01994               __new_buckets[__bkt]->_M_nxt = __p;
01995             }
01996           __p = __next;
01997         }
01998 
01999       _M_deallocate_buckets();
02000       _M_bucket_count = __n;
02001       _M_buckets = __new_buckets;
02002     }
02003 
02004   // Rehash when there can be equivalent elements, preserve their relative
02005   // order.
02006   template<typename _Key, typename _Value,
02007            typename _Alloc, typename _ExtractKey, typename _Equal,
02008            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
02009            typename _Traits>
02010     void
02011     _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
02012                _H1, _H2, _Hash, _RehashPolicy, _Traits>::
02013     _M_rehash_aux(size_type __n, std::false_type)
02014     {
02015       __bucket_type* __new_buckets = _M_allocate_buckets(__n);
02016 
02017       __node_type* __p = _M_begin();
02018       _M_before_begin._M_nxt = nullptr;
02019       std::size_t __bbegin_bkt = 0;
02020       std::size_t __prev_bkt = 0;
02021       __node_type* __prev_p = nullptr;
02022       bool __check_bucket = false;
02023 
02024       while (__p)
02025         {
02026           __node_type* __next = __p->_M_next();
02027           std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
02028 
02029           if (__prev_p && __prev_bkt == __bkt)
02030             {
02031               // Previous insert was already in this bucket, we insert after
02032               // the previously inserted one to preserve equivalent elements
02033               // relative order.
02034               __p->_M_nxt = __prev_p->_M_nxt;
02035               __prev_p->_M_nxt = __p;
02036 
02037               // Inserting after a node in a bucket require to check that we
02038               // haven't change the bucket last node, in this case next
02039               // bucket containing its before begin node must be updated. We
02040               // schedule a check as soon as we move out of the sequence of
02041               // equivalent nodes to limit the number of checks.
02042               __check_bucket = true;
02043             }
02044           else
02045             {
02046               if (__check_bucket)
02047                 {
02048                   // Check if we shall update the next bucket because of
02049                   // insertions into __prev_bkt bucket.
02050                   if (__prev_p->_M_nxt)
02051                     {
02052                       std::size_t __next_bkt
02053                         = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
02054                                                             __n);
02055                       if (__next_bkt != __prev_bkt)
02056                         __new_buckets[__next_bkt] = __prev_p;
02057                     }
02058                   __check_bucket = false;
02059                 }
02060 
02061               if (!__new_buckets[__bkt])
02062                 {
02063                   __p->_M_nxt = _M_before_begin._M_nxt;
02064                   _M_before_begin._M_nxt = __p;
02065                   __new_buckets[__bkt] = &_M_before_begin;
02066                   if (__p->_M_nxt)
02067                     __new_buckets[__bbegin_bkt] = __p;
02068                   __bbegin_bkt = __bkt;
02069                 }
02070               else
02071                 {
02072                   __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
02073                   __new_buckets[__bkt]->_M_nxt = __p;
02074                 }
02075             }
02076           __prev_p = __p;
02077           __prev_bkt = __bkt;
02078           __p = __next;
02079         }
02080 
02081       if (__check_bucket && __prev_p->_M_nxt)
02082         {
02083           std::size_t __next_bkt
02084             = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
02085           if (__next_bkt != __prev_bkt)
02086             __new_buckets[__next_bkt] = __prev_p;
02087         }
02088 
02089       _M_deallocate_buckets();
02090       _M_bucket_count = __n;
02091       _M_buckets = __new_buckets;
02092     }
02093 
02094 _GLIBCXX_END_NAMESPACE_VERSION
02095 } // namespace std
02096 
02097 #endif // _HASHTABLE_H