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// hashtable.h header -*- C++ -*-

// Copyright (C) 2007-2013 Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library is free

// software; you can redistribute it and/or modify it under the

// terms of the GNU General Public License as published by the

// Free Software Foundation; either version 3, or (at your option)

// any later version.

// This library is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// .

/** @file bits/hashtable.h

 *  This is an internal header file, included by other library headers.

 *  Do not attempt to use it directly. @headername{unordered_map, unordered_set}

 */

#ifndef _HASHTABLE_H

#define _HASHTABLE_H 1

#pragma GCC system_header

#include 

namespace std _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  template

    using __cache_default

      =  __not_<__and_

		       __is_fast_hash<_Hash>,

		       // Mandatory to make local_iterator default

		       // constructible and assignable.

		       is_default_constructible<_Hash>,

		       is_copy_assignable<_Hash>,

		       // Mandatory to have erase not throwing.

		       __detail::__is_noexcept_hash<_Tp, _Hash>>>;

  /**

   *  Primary class template _Hashtable.

   *

   *  @ingroup hashtable-detail

   *

   *  @tparam _Value  CopyConstructible type.

   *

   *  @tparam _Key    CopyConstructible type.

   *

   *  @tparam _Alloc  An allocator type

   *  ([lib.allocator.requirements]) whose _Alloc::value_type is

   *  _Value.  As a conforming extension, we allow for

   *  _Alloc::value_type != _Value.

   *

   *  @tparam _ExtractKey  Function object that takes an object of type

   *  _Value and returns a value of type _Key.

   *

   *  @tparam _Equal  Function object that takes two objects of type k

   *  and returns a bool-like value that is true if the two objects

   *  are considered equal.

   *

   *  @tparam _H1  The hash function. A unary function object with

   *  argument type _Key and result type size_t. Return values should

   *  be distributed over the entire range [0, numeric_limits:::max()].

   *

   *  @tparam _H2  The range-hashing function (in the terminology of

   *  Tavori and Dreizin).  A binary function object whose argument

   *  types and result type are all size_t.  Given arguments r and N,

   *  the return value is in the range [0, N).

   *

   *  @tparam _Hash  The ranged hash function (Tavori and Dreizin). A

   *  binary function whose argument types are _Key and size_t and

   *  whose result type is size_t.  Given arguments k and N, the

   *  return value is in the range [0, N).  Default: hash(k, N) =

   *  h2(h1(k), N).  If _Hash is anything other than the default, _H1

   *  and _H2 are ignored.

   *

   *  @tparam _RehashPolicy  Policy class with three members, all of

   *  which govern the bucket count. _M_next_bkt(n) returns a bucket

   *  count no smaller than n.  _M_bkt_for_elements(n) returns a

   *  bucket count appropriate for an element count of n.

   *  _M_need_rehash(n_bkt, n_elt, n_ins) determines whether, if the

   *  current bucket count is n_bkt and the current element count is

   *  n_elt, we need to increase the bucket count.  If so, returns

   *  make_pair(true, n), where n is the new bucket count.  If not,

   *  returns make_pair(false, )

   *

   *  @tparam _Traits  Compile-time class with three boolean

   *  std::integral_constant members:  __cache_hash_code, __constant_iterators,

   *   __unique_keys.

   *

   *  Each _Hashtable data structure has:

   *

   *  - _Bucket[]       _M_buckets

   *  - _Hash_node_base _M_bbegin

   *  - size_type       _M_bucket_count

   *  - size_type       _M_element_count

   *

   *  with _Bucket being _Hash_node* and _Hash_node containing:

   *

   *  - _Hash_node*   _M_next

   *  - Tp            _M_value

   *  - size_t        _M_hash_code if cache_hash_code is true

   *

   *  In terms of Standard containers the hashtable is like the aggregation of:

   *

   *  - std::forward_list<_Node> containing the elements

   *  - std::vector::iterator> representing the buckets

   *

   *  The non-empty buckets contain the node before the first node in the

   *  bucket. This design makes it possible to implement something like a

   *  std::forward_list::insert_after on container insertion and

   *  std::forward_list::erase_after on container erase

   *  calls. _M_before_begin is equivalent to

   *  std::forward_list::before_begin. Empty buckets contain

   *  nullptr.  Note that one of the non-empty buckets contains

   *  &_M_before_begin which is not a dereferenceable node so the

   *  node pointer in a bucket shall never be dereferenced, only its

   *  next node can be.

   *

   *  Walking through a bucket's nodes requires a check on the hash code to

   *  see if each node is still in the bucket. Such a design assumes a

   *  quite efficient hash functor and is one of the reasons it is

   *  highly advisable to set __cache_hash_code to true.

   *

   *  The container iterators are simply built from nodes. This way

   *  incrementing the iterator is perfectly efficient independent of

   *  how many empty buckets there are in the container.

   *

   *  On insert we compute the element's hash code and use it to find the

   *  bucket index. If the element must be inserted in an empty bucket

   *  we add it at the beginning of the singly linked list and make the

   *  bucket point to _M_before_begin. The bucket that used to point to

   *  _M_before_begin, if any, is updated to point to its new before

   *  begin node.

   *

   *  On erase, the simple iterator design requires using the hash

   *  functor to get the index of the bucket to update. For this

   *  reason, when __cache_hash_code is set to false the hash functor must

   *  not throw and this is enforced by a static assertion.

   *

   *  Functionality is implemented by decomposition into base classes,

   *  where the derived _Hashtable class is used in _Map_base,

   *  _Insert, _Rehash_base, and _Equality base classes to access the

   *  "this" pointer. _Hashtable_base is used in the base classes as a

   *  non-recursive, fully-completed-type so that detailed nested type

   *  information, such as iterator type and node type, can be

   *  used. This is similar to the "Curiously Recurring Template

   *  Pattern" (CRTP) technique, but uses a reconstructed, not

   *  explicitly passed, template pattern.

   *

   *  Base class templates are:

   *    - __detail::_Hashtable_base

   *    - __detail::_Map_base

   *    - __detail::_Insert

   *    - __detail::_Rehash_base

   *    - __detail::_Equality

   */

  template

	   typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash,

	   typename _RehashPolicy, typename _Traits>

    class _Hashtable

    : public __detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal,

				       _H1, _H2, _Hash, _Traits>,

      public __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,

				 _H1, _H2, _Hash, _RehashPolicy, _Traits>,

      public __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,

			       _H1, _H2, _Hash, _RehashPolicy, _Traits>,

      public __detail::_Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,

				    _H1, _H2, _Hash, _RehashPolicy, _Traits>,

      public __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,

				 _H1, _H2, _Hash, _RehashPolicy, _Traits>

    {

    public:

      typedef _Key                                    key_type;

      typedef _Value                                  value_type;

      typedef _Alloc                                  allocator_type;

      typedef _Equal                                  key_equal;

      // mapped_type, if present, comes from _Map_base.

      // hasher, if present, comes from _Hash_code_base/_Hashtable_base.

      typedef typename _Alloc::pointer		      pointer;

      typedef typename _Alloc::const_pointer          const_pointer;

      typedef typename _Alloc::reference              reference;

      typedef typename _Alloc::const_reference        const_reference;

    private:

      using __rehash_type = _RehashPolicy;

      using __rehash_state = typename __rehash_type::_State;

      using __traits_type = _Traits;

      using __hash_cached = typename __traits_type::__hash_cached;

      using __constant_iterators = typename __traits_type::__constant_iterators;

      using __unique_keys = typename __traits_type::__unique_keys;

      using __key_extract = typename std::conditional<

					     __constant_iterators::value,

				       	     __detail::_Identity,

					     __detail::_Select1st>::type;

      using __hashtable_base = __detail::

			       _Hashtable_base<_Key, _Value, _ExtractKey,

					      _Equal, _H1, _H2, _Hash, _Traits>;

      using __hash_code_base =  typename __hashtable_base::__hash_code_base;

      using __hash_code =  typename __hashtable_base::__hash_code;

      using __node_type = typename __hashtable_base::__node_type;

      using __node_base = typename __hashtable_base::__node_base;

      using __bucket_type = typename __hashtable_base::__bucket_type;

      using __ireturn_type = typename __hashtable_base::__ireturn_type;

      using __iconv_type = typename __hashtable_base::__iconv_type;

      using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,

					     _Equal, _H1, _H2, _Hash,

					     _RehashPolicy, _Traits>;

      using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,

						   _ExtractKey, _Equal,

						   _H1, _H2, _Hash,

						   _RehashPolicy, _Traits>;

      using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,

					    _Equal, _H1, _H2, _Hash,

					    _RehashPolicy, _Traits>;

      // Metaprogramming for picking apart hash caching.

      using __hash_noexcept = __detail::__is_noexcept_hash<_Key, _H1>;

      template

	using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;

      template

	using __if_hash_not_cached = __or_<__hash_cached, _Cond>;

      // Compile-time diagnostics.

      // When hash codes are not cached the hash functor shall not

      // throw because it is used in methods (erase, swap...) that

      // shall not throw.

      static_assert(__if_hash_not_cached<__hash_noexcept>::value,

		    "Cache the hash code"

		    " or qualify your hash functor with noexcept");

      // Following two static assertions are necessary to guarantee

      // that local_iterator will be default constructible.

      // When hash codes are cached local iterator inherits from H2 functor

      // which must then be default constructible.

      static_assert(__if_hash_cached>::value,

		    "Functor used to map hash code to bucket index"

		    " must be default constructible");

      // When hash codes are not cached local iterator inherits from

      // __hash_code_base above to compute node bucket index so it has to be

      // default constructible.

      static_assert(__if_hash_not_cached<

		    is_default_constructible<

		      // We use _Hashtable_ebo_helper to access the protected

		      // default constructor.

		      __detail::_Hashtable_ebo_helper<0, __hash_code_base>>>::value,

		    "Cache the hash code or make functors involved in hash code"

		    " and bucket index computation default constructible");

      // When hash codes are not cached local iterator inherits from

      // __hash_code_base above to compute node bucket index so it has to be

      // assignable.

      static_assert(__if_hash_not_cached<

		      is_copy_assignable<__hash_code_base>>::value,

		    "Cache the hash code or make functors involved in hash code"

		    " and bucket index computation copy assignable");

    public:

      template

	       typename _ExtractKeya, typename _Equala,

	       typename _H1a, typename _H2a, typename _Hasha,

	       typename _RehashPolicya, typename _Traitsa,

	       bool _Unique_keysa>

	friend struct __detail::_Map_base;

      template

	       typename _ExtractKeya, typename _Equala,

	       typename _H1a, typename _H2a, typename _Hasha,

	       typename _RehashPolicya, typename _Traitsa>

	friend struct __detail::_Insert_base;

      template

	       typename _ExtractKeya, typename _Equala,

	       typename _H1a, typename _H2a, typename _Hasha,

	       typename _RehashPolicya, typename _Traitsa,

	       bool _Constant_iteratorsa, bool _Unique_keysa>

	friend struct __detail::_Insert;

      using size_type = typename __hashtable_base::size_type;

      using difference_type = typename __hashtable_base::difference_type;

      using iterator = typename __hashtable_base::iterator;

      using const_iterator = typename __hashtable_base::const_iterator;

      using local_iterator = typename __hashtable_base::local_iterator;

      using const_local_iterator = typename __hashtable_base::

				   const_local_iterator;

    private:

      typedef typename _Alloc::template rebind<__node_type>::other

							_Node_allocator_type;

      typedef typename _Alloc::template rebind<__bucket_type>::other

							_Bucket_allocator_type;

      using __before_begin = __detail::_Before_begin<_Node_allocator_type>;

      __bucket_type*		_M_buckets;

      size_type			_M_bucket_count;

      __before_begin		_M_bbegin;

      size_type			_M_element_count;

      _RehashPolicy		_M_rehash_policy;

      _Node_allocator_type&

      _M_node_allocator()

      { return _M_bbegin; }

      const _Node_allocator_type&

      _M_node_allocator() const

      { return _M_bbegin; }

      __node_base&

      _M_before_begin()

      { return _M_bbegin._M_node; }

      const __node_base&

      _M_before_begin() const

      { return _M_bbegin._M_node; }

      template

	__node_type*

	_M_allocate_node(_Args&&... __args);

      void

      _M_deallocate_node(__node_type* __n);

      // Deallocate the linked list of nodes pointed to by __n

      void

      _M_deallocate_nodes(__node_type* __n);

      __bucket_type*

      _M_allocate_buckets(size_type __n);

      void

      _M_deallocate_buckets(__bucket_type*, size_type __n);

      // Gets bucket begin, deals with the fact that non-empty buckets contain

      // their before begin node.

      __node_type*

      _M_bucket_begin(size_type __bkt) const;

      __node_type*

      _M_begin() const

      { return static_cast<__node_type*>(_M_before_begin()._M_nxt); }

    public:

      // Constructor, destructor, assignment, swap

      _Hashtable(size_type __bucket_hint,

		 const _H1&, const _H2&, const _Hash&,

		 const _Equal&, const _ExtractKey&,

		 const allocator_type&);

      template

	_Hashtable(_InputIterator __first, _InputIterator __last,

		   size_type __bucket_hint,

		   const _H1&, const _H2&, const _Hash&,

		   const _Equal&, const _ExtractKey&,

		   const allocator_type&);

      _Hashtable(const _Hashtable&);

      _Hashtable(_Hashtable&&);

      // Use delegating constructors.

      explicit

      _Hashtable(size_type __n = 10,

		 const _H1& __hf = _H1(),

		 const key_equal& __eql = key_equal(),

		 const allocator_type& __a = allocator_type())

      : _Hashtable(__n, __hf, __detail::_Mod_range_hashing(),

		   __detail::_Default_ranged_hash(), __eql,

		   __key_extract(), __a)

      { }

      template

	_Hashtable(_InputIterator __f, _InputIterator __l,

		   size_type __n = 0,

		   const _H1& __hf = _H1(),

		   const key_equal& __eql = key_equal(),

		   const allocator_type& __a = allocator_type())

	: _Hashtable(__f, __l, __n, __hf, __detail::_Mod_range_hashing(),

		     __detail::_Default_ranged_hash(), __eql,

		     __key_extract(), __a)

	{ }

      _Hashtable(initializer_list __l,

		 size_type __n = 0,

		 const _H1& __hf = _H1(),

		 const key_equal& __eql = key_equal(),

		 const allocator_type& __a = allocator_type())

      : _Hashtable(__l.begin(), __l.end(), __n, __hf,

		   __detail::_Mod_range_hashing(),

		   __detail::_Default_ranged_hash(), __eql,

		   __key_extract(), __a)

      { }

      _Hashtable&

      operator=(const _Hashtable& __ht)

      {

	_Hashtable __tmp(__ht);

	this->swap(__tmp);

	return *this;

      }

      _Hashtable&

      operator=(_Hashtable&& __ht)

      {

	// NB: DR 1204.

	// NB: DR 675.

	this->clear();

	this->swap(__ht);

	return *this;

      }

      _Hashtable&

      operator=(initializer_list __l)

      {

	this->clear();

	this->insert(__l.begin(), __l.end());

	return *this;

      }

      ~_Hashtable() noexcept;

      void swap(_Hashtable&);

      // Basic container operations

      iterator

      begin() noexcept

      { return iterator(_M_begin()); }

      const_iterator

      begin() const noexcept

      { return const_iterator(_M_begin()); }

      iterator

      end() noexcept

      { return iterator(nullptr); }

      const_iterator

      end() const noexcept

      { return const_iterator(nullptr); }

      const_iterator

      cbegin() const noexcept

      { return const_iterator(_M_begin()); }

      const_iterator

      cend() const noexcept

      { return const_iterator(nullptr); }

      size_type

      size() const noexcept

      { return _M_element_count; }

      bool

      empty() const noexcept

      { return size() == 0; }

      allocator_type

      get_allocator() const noexcept

      { return allocator_type(_M_node_allocator()); }

      size_type

      max_size() const noexcept

      { return _M_node_allocator().max_size(); }

      // Observers

      key_equal

      key_eq() const

      { return this->_M_eq(); }

      // hash_function, if present, comes from _Hash_code_base.

      // Bucket operations

      size_type

      bucket_count() const noexcept

      { return _M_bucket_count; }

      size_type

      max_bucket_count() const noexcept

      { return max_size(); }

      size_type

      bucket_size(size_type __n) const

      { return std::distance(begin(__n), end(__n)); }

      size_type

      bucket(const key_type& __k) const

      { return _M_bucket_index(__k, this->_M_hash_code(__k)); }

      local_iterator

      begin(size_type __n)

      {

	return local_iterator(*this, _M_bucket_begin(__n),

			      __n, _M_bucket_count);

      }

      local_iterator

      end(size_type __n)

      { return local_iterator(*this, nullptr, __n, _M_bucket_count); }

      const_local_iterator

      begin(size_type __n) const

      {

	return const_local_iterator(*this, _M_bucket_begin(__n),

				    __n, _M_bucket_count);

      }

      const_local_iterator

      end(size_type __n) const

      { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }

      // DR 691.

      const_local_iterator

      cbegin(size_type __n) const

      {

	return const_local_iterator(*this, _M_bucket_begin(__n),

				    __n, _M_bucket_count);

      }

      const_local_iterator

      cend(size_type __n) const

      { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }

      float

      load_factor() const noexcept

      {

	return static_cast(size()) / static_cast(bucket_count());

      }

      // max_load_factor, if present, comes from _Rehash_base.

      // Generalization of max_load_factor.  Extension, not found in

      // TR1.  Only useful if _RehashPolicy is something other than

      // the default.

      const _RehashPolicy&

      __rehash_policy() const

      { return _M_rehash_policy; }

      void

      __rehash_policy(const _RehashPolicy&);

      // Lookup.

      iterator

      find(const key_type& __k);

      const_iterator

      find(const key_type& __k) const;

      size_type

      count(const key_type& __k) const;

      std::pair

      equal_range(const key_type& __k);

      std::pair

      equal_range(const key_type& __k) const;

    protected:

      // Bucket index computation helpers.

      size_type

      _M_bucket_index(__node_type* __n) const

      { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }

      size_type

      _M_bucket_index(const key_type& __k, __hash_code __c) const

      { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }

      // Find and insert helper functions and types

      // Find the node before the one matching the criteria.

      __node_base*

      _M_find_before_node(size_type, const key_type&, __hash_code) const;

      __node_type*

      _M_find_node(size_type __bkt, const key_type& __key,

		   __hash_code __c) const

      {

	__node_base* __before_n = _M_find_before_node(__bkt, __key, __c);

	if (__before_n)

	  return static_cast<__node_type*>(__before_n->_M_nxt);

	return nullptr;

      }

      // Insert a node at the beginning of a bucket.

      void

      _M_insert_bucket_begin(size_type, __node_type*);

      // Remove the bucket first node

      void

      _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,

			     size_type __next_bkt);

      // Get the node before __n in the bucket __bkt

      __node_base*

      _M_get_previous_node(size_type __bkt, __node_base* __n);

      // Insert node with hash code __code, in bucket bkt if no rehash (assumes

      // no element with its key already present). Take ownership of the node,

      // deallocate it on exception.

      iterator

      _M_insert_unique_node(size_type __bkt, __hash_code __code,

			    __node_type* __n);

      // Insert node with hash code __code. Take ownership of the node,

      // deallocate it on exception.

      iterator

      _M_insert_multi_node(__hash_code __code, __node_type* __n);

      template

	std::pair

	_M_emplace(std::true_type, _Args&&... __args);

      template

	iterator

	_M_emplace(std::false_type, _Args&&... __args);

      template

	std::pair

	_M_insert(_Arg&&, std::true_type);

      template

	iterator

	_M_insert(_Arg&&, std::false_type);

      size_type

      _M_erase(std::true_type, const key_type&);

      size_type

      _M_erase(std::false_type, const key_type&);

      iterator

      _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);

    public:

      // Emplace

      template

	__ireturn_type

	emplace(_Args&&... __args)

	{ return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }

      template

	iterator

	emplace_hint(const_iterator, _Args&&... __args)

	{ return __iconv_type()(emplace(std::forward<_Args>(__args)...)); }

      // Insert member functions via inheritance.

      // Erase

      iterator

      erase(const_iterator);

      // LWG 2059.

      iterator

      erase(iterator __it)

      { return erase(const_iterator(__it)); }

      size_type

      erase(const key_type& __k)

      { return _M_erase(__unique_keys(), __k); }

      iterator

      erase(const_iterator, const_iterator);

      void

      clear() noexcept;

      // Set number of buckets to be appropriate for container of n element.

      void rehash(size_type __n);

      // DR 1189.

      // reserve, if present, comes from _Rehash_base.

    private:

      // Helper rehash method used when keys are unique.

      void _M_rehash_aux(size_type __n, std::true_type);

      // Helper rehash method used when keys can be non-unique.

      void _M_rehash_aux(size_type __n, std::false_type);

      // Unconditionally change size of bucket array to n, restore

      // hash policy state to __state on exception.

      void _M_rehash(size_type __n, const __rehash_state& __state);

    };

  // Definitions of class template _Hashtable's out-of-line member functions.

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    template

      typename _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

			  _H1, _H2, _Hash, _RehashPolicy, _Traits>::__node_type*

      _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

		 _H1, _H2, _Hash, _RehashPolicy, _Traits>::

      _M_allocate_node(_Args&&... __args)

      {

	__node_type* __n = _M_node_allocator().allocate(1);

	__try

	  {

	    _M_node_allocator().construct(__n, std::forward<_Args>(__args)...);

	    return __n;

	  }

	__catch(...)

	  {

	    _M_node_allocator().deallocate(__n, 1);

	    __throw_exception_again;

	  }

      }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    void

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _M_deallocate_node(__node_type* __n)

    {

      _M_node_allocator().destroy(__n);

      _M_node_allocator().deallocate(__n, 1);

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    void

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _M_deallocate_nodes(__node_type* __n)

    {

      while (__n)

	{

	  __node_type* __tmp = __n;

	  __n = __n->_M_next();

	  _M_deallocate_node(__tmp);

	}

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    typename _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

			_H1, _H2, _Hash, _RehashPolicy, _Traits>::__bucket_type*

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _M_allocate_buckets(size_type __n)

    {

      _Bucket_allocator_type __alloc(_M_node_allocator());

      __bucket_type* __p = __alloc.allocate(__n);

      __builtin_memset(__p, 0, __n * sizeof(__bucket_type));

      return __p;

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    void

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _M_deallocate_buckets(__bucket_type* __p, size_type __n)

    {

      _Bucket_allocator_type __alloc(_M_node_allocator());

      __alloc.deallocate(__p, __n);

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    typename _Hashtable<_Key, _Value, _Alloc, _ExtractKey,

			_Equal, _H1, _H2, _Hash, _RehashPolicy,

			_Traits>::__node_type*

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _M_bucket_begin(size_type __bkt) const

    {

      __node_base* __n = _M_buckets[__bkt];

      return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _Hashtable(size_type __bucket_hint,

	       const _H1& __h1, const _H2& __h2, const _Hash& __h,

	       const _Equal& __eq, const _ExtractKey& __exk,

	       const allocator_type& __a)

    : __hashtable_base(__exk, __h1, __h2, __h, __eq),

      __map_base(),

      __rehash_base(),

      _M_bucket_count(0),

      _M_bbegin(__a),

      _M_element_count(0),

      _M_rehash_policy()

    {

      _M_bucket_count = _M_rehash_policy._M_next_bkt(__bucket_hint);

      _M_buckets = _M_allocate_buckets(_M_bucket_count);

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    template

      _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

		 _H1, _H2, _Hash, _RehashPolicy, _Traits>::

      _Hashtable(_InputIterator __f, _InputIterator __l,

		 size_type __bucket_hint,

		 const _H1& __h1, const _H2& __h2, const _Hash& __h,

		 const _Equal& __eq, const _ExtractKey& __exk,

		 const allocator_type& __a)

      : __hashtable_base(__exk, __h1, __h2, __h, __eq),

	__map_base(),

	__rehash_base(),

	_M_bucket_count(0),

	_M_bbegin(__a),

	_M_element_count(0),

	_M_rehash_policy()

      {

	auto __nb_elems = __detail::__distance_fw(__f, __l);

	_M_bucket_count =

	  _M_rehash_policy._M_next_bkt(

	    std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),

		     __bucket_hint));

	_M_buckets = _M_allocate_buckets(_M_bucket_count);

	__try

	  {

	    for (; __f != __l; ++__f)

	      this->insert(*__f);

	  }

	__catch(...)

	  {

	    clear();

	    _M_deallocate_buckets(_M_buckets, _M_bucket_count);

	    __throw_exception_again;

	  }

      }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _Hashtable(const _Hashtable& __ht)

    : __hashtable_base(__ht),

      __map_base(__ht),

      __rehash_base(__ht),

      _M_bucket_count(__ht._M_bucket_count),

      _M_bbegin(__ht._M_bbegin),

      _M_element_count(__ht._M_element_count),

      _M_rehash_policy(__ht._M_rehash_policy)

    {

      _M_buckets = _M_allocate_buckets(_M_bucket_count);

      __try

	{

	  if (!__ht._M_before_begin()._M_nxt)

	    return;

	  // First deal with the special first node pointed to by

	  // _M_before_begin.

	  const __node_type* __ht_n = __ht._M_begin();

	  __node_type* __this_n = _M_allocate_node(__ht_n->_M_v);

	  this->_M_copy_code(__this_n, __ht_n);

	  _M_before_begin()._M_nxt = __this_n;

	  _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin();

	  // Then deal with other nodes.

	  __node_base* __prev_n = __this_n;

	  for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())

	    {

	      __this_n = _M_allocate_node(__ht_n->_M_v);

	      __prev_n->_M_nxt = __this_n;

	      this->_M_copy_code(__this_n, __ht_n);

	      size_type __bkt = _M_bucket_index(__this_n);

	      if (!_M_buckets[__bkt])

		_M_buckets[__bkt] = __prev_n;

	      __prev_n = __this_n;

	    }

	}

      __catch(...)

	{

	  clear();

	  _M_deallocate_buckets(_M_buckets, _M_bucket_count);

	  __throw_exception_again;

	}

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    _Hashtable(_Hashtable&& __ht)

    : __hashtable_base(__ht),

      __map_base(__ht),

      __rehash_base(__ht),

      _M_buckets(__ht._M_buckets),

      _M_bucket_count(__ht._M_bucket_count),

      _M_bbegin(std::move(__ht._M_bbegin)),

      _M_element_count(__ht._M_element_count),

      _M_rehash_policy(__ht._M_rehash_policy)

    {

      // Update, if necessary, bucket pointing to before begin that hasn't moved.

      if (_M_begin())

	_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin();

      __ht._M_rehash_policy = _RehashPolicy();

      __ht._M_bucket_count = __ht._M_rehash_policy._M_next_bkt(0);

      __ht._M_buckets = __ht._M_allocate_buckets(__ht._M_bucket_count);

      __ht._M_before_begin()._M_nxt = nullptr;

      __ht._M_element_count = 0;

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    ~_Hashtable() noexcept

    {

      clear();

      _M_deallocate_buckets(_M_buckets, _M_bucket_count);

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    void

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    swap(_Hashtable& __x)

    {

      // The only base class with member variables is hash_code_base.

      // We define _Hash_code_base::_M_swap because different

      // specializations have different members.

      this->_M_swap(__x);

      // _GLIBCXX_RESOLVE_LIB_DEFECTS

      // 431. Swapping containers with unequal allocators.

      std::__alloc_swap<_Node_allocator_type>::_S_do_it(_M_node_allocator(),

							__x._M_node_allocator());

      std::swap(_M_rehash_policy, __x._M_rehash_policy);

      std::swap(_M_buckets, __x._M_buckets);

      std::swap(_M_bucket_count, __x._M_bucket_count);

      std::swap(_M_before_begin()._M_nxt, __x._M_before_begin()._M_nxt);

      std::swap(_M_element_count, __x._M_element_count);

      // Fix buckets containing the _M_before_begin pointers that

      // can't be swapped.

      if (_M_begin())

	_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin();

      if (__x._M_begin())

	__x._M_buckets[__x._M_bucket_index(__x._M_begin())]

	  = &(__x._M_before_begin());

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    void

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    __rehash_policy(const _RehashPolicy& __pol)

    {

      size_type __n_bkt = __pol._M_bkt_for_elements(_M_element_count);

      __n_bkt = __pol._M_next_bkt(__n_bkt);

      if (__n_bkt != _M_bucket_count)

	_M_rehash(__n_bkt, _M_rehash_policy._M_state());

      _M_rehash_policy = __pol;

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    typename _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

			_H1, _H2, _Hash, _RehashPolicy,

			_Traits>::iterator

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    find(const key_type& __k)

    {

      __hash_code __code = this->_M_hash_code(__k);

      std::size_t __n = _M_bucket_index(__k, __code);

      __node_type* __p = _M_find_node(__n, __k, __code);

      return __p ? iterator(__p) : this->end();

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    typename _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

			_H1, _H2, _Hash, _RehashPolicy,

			_Traits>::const_iterator

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    find(const key_type& __k) const

    {

      __hash_code __code = this->_M_hash_code(__k);

      std::size_t __n = _M_bucket_index(__k, __code);

      __node_type* __p = _M_find_node(__n, __k, __code);

      return __p ? const_iterator(__p) : this->end();

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    typename _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

			_H1, _H2, _Hash, _RehashPolicy,

			_Traits>::size_type

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    count(const key_type& __k) const

    {

      __hash_code __code = this->_M_hash_code(__k);

      std::size_t __n = _M_bucket_index(__k, __code);

      __node_type* __p = _M_bucket_begin(__n);

      if (!__p)

	return 0;

      std::size_t __result = 0;

      for (;; __p = __p->_M_next())

	{

	  if (this->_M_equals(__k, __code, __p))

	    ++__result;

	  else if (__result)

	    // All equivalent values are next to each other, if we

	    // found a non-equivalent value after an equivalent one it

	    // means that we won't find any more equivalent values.

	    break;

	  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)

	    break;

	}

      return __result;

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    std::pair

				  _ExtractKey, _Equal, _H1,

				  _H2, _Hash, _RehashPolicy,

				  _Traits>::iterator,

	      typename _Hashtable<_Key, _Value, _Alloc,

				  _ExtractKey, _Equal, _H1,

				  _H2, _Hash, _RehashPolicy,

				  _Traits>::iterator>

    _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,

	       _H1, _H2, _Hash, _RehashPolicy, _Traits>::

    equal_range(const key_type& __k)

    {

      __hash_code __code = this->_M_hash_code(__k);

      std::size_t __n = _M_bucket_index(__k, __code);

      __node_type* __p = _M_find_node(__n, __k, __code);

      if (__p)

	{

	  __node_type* __p1 = __p->_M_next();

	  while (__p1 && _M_bucket_index(__p1) == __n

		 && this->_M_equals(__k, __code, __p1))

	    __p1 = __p1->_M_next();

	  return std::make_pair(iterator(__p), iterator(__p1));

	}

      else

	return std::make_pair(this->end(), this->end());

    }

  template

	   typename _Alloc, typename _ExtractKey, typename _Equal,

	   typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,

	   typename _Traits>

    std::pair

				  _ExtractKey, _Equal, _H1,

				  _H2, _Hash, _RehashPolicy,

				  _Traits>::const_iterator,

	      typename _Hashtable<_Key, _Value, _Alloc,

				  _ExtractKey, _Equal, _H1,

				  _H2, _Hash, _RehashPolicy,