// Internal policy header for unordered_set and unordered_map -*- C++ -*-
	
	// Copyright (C) 2010-2019 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
	// <http://www.gnu.org/licenses/>.
	
	/** @file bits/hashtable_policy.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_POLICY_H
	#define _HASHTABLE_POLICY_H 1
	
	#include <tuple>		// for std::tuple, std::forward_as_tuple
	#include <limits>		// for std::numeric_limits
	#include <bits/stl_algobase.h>	// for std::min.
	
	namespace std _GLIBCXX_VISIBILITY(default)
	{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    class _Hashtable;
	
	namespace __detail
	{
	  /**
	   *  @defgroup hashtable-detail Base and Implementation Classes
	   *  @ingroup unordered_associative_containers
	   *  @{
	   */
	  template<typename _Key, typename _Value,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash, typename _Traits>
	    struct _Hashtable_base;
	
	  // Helper function: return distance(first, last) for forward
	  // iterators, or 0/1 for input iterators.
	  template<class _Iterator>
	    inline typename std::iterator_traits<_Iterator>::difference_type
	    __distance_fw(_Iterator __first, _Iterator __last,
			  std::input_iterator_tag)
	    { return __first != __last ? 1 : 0; }
	
	  template<class _Iterator>
	    inline typename std::iterator_traits<_Iterator>::difference_type
	    __distance_fw(_Iterator __first, _Iterator __last,
			  std::forward_iterator_tag)
	    { return std::distance(__first, __last); }
	
	  template<class _Iterator>
	    inline typename std::iterator_traits<_Iterator>::difference_type
	    __distance_fw(_Iterator __first, _Iterator __last)
	    { return __distance_fw(__first, __last,
				   std::__iterator_category(__first)); }
	
	  struct _Identity
	  {
	    template<typename _Tp>
	      _Tp&&
	      operator()(_Tp&& __x) const
	      { return std::forward<_Tp>(__x); }
	  };
	
	  struct _Select1st
	  {
	    template<typename _Tp>
	      auto
	      operator()(_Tp&& __x) const
	      -> decltype(std::get<0>(std::forward<_Tp>(__x)))
	      { return std::get<0>(std::forward<_Tp>(__x)); }
	  };
	
	  template<typename _NodeAlloc>
	    struct _Hashtable_alloc;
	
	  // Functor recycling a pool of nodes and using allocation once the pool is
	  // empty.
	  template<typename _NodeAlloc>
	    struct _ReuseOrAllocNode
	    {
	    private:
	      using __node_alloc_type = _NodeAlloc;
	      using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
	      using __node_alloc_traits =
		typename __hashtable_alloc::__node_alloc_traits;
	      using __node_type = typename __hashtable_alloc::__node_type;
	
	    public:
	      _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
		: _M_nodes(__nodes), _M_h(__h) { }
	      _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
	
	      ~_ReuseOrAllocNode()
	      { _M_h._M_deallocate_nodes(_M_nodes); }
	
	      template<typename _Arg>
		__node_type*
		operator()(_Arg&& __arg) const
		{
		  if (_M_nodes)
		    {
		      __node_type* __node = _M_nodes;
		      _M_nodes = _M_nodes->_M_next();
		      __node->_M_nxt = nullptr;
		      auto& __a = _M_h._M_node_allocator();
		      __node_alloc_traits::destroy(__a, __node->_M_valptr());
		      __try
			{
			  __node_alloc_traits::construct(__a, __node->_M_valptr(),
							 std::forward<_Arg>(__arg));
			}
		      __catch(...)
			{
			  _M_h._M_deallocate_node_ptr(__node);
			  __throw_exception_again;
			}
		      return __node;
		    }
		  return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
		}
	
	    private:
	      mutable __node_type* _M_nodes;
	      __hashtable_alloc& _M_h;
	    };
	
	  // Functor similar to the previous one but without any pool of nodes to
	  // recycle.
	  template<typename _NodeAlloc>
	    struct _AllocNode
	    {
	    private:
	      using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
	      using __node_type = typename __hashtable_alloc::__node_type;
	
	    public:
	      _AllocNode(__hashtable_alloc& __h)
		: _M_h(__h) { }
	
	      template<typename _Arg>
		__node_type*
		operator()(_Arg&& __arg) const
		{ return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
	
	    private:
	      __hashtable_alloc& _M_h;
	    };
	
	  // Auxiliary types used for all instantiations of _Hashtable nodes
	  // and iterators.
	
	  /**
	   *  struct _Hashtable_traits
	   *
	   *  Important traits for hash tables.
	   *
	   *  @tparam _Cache_hash_code  Boolean value. True if the value of
	   *  the hash function is stored along with the value. This is a
	   *  time-space tradeoff.  Storing it may improve lookup speed by
	   *  reducing the number of times we need to call the _Equal
	   *  function.
	   *
	   *  @tparam _Constant_iterators  Boolean value. True if iterator and
	   *  const_iterator are both constant iterator types. This is true
	   *  for unordered_set and unordered_multiset, false for
	   *  unordered_map and unordered_multimap.
	   *
	   *  @tparam _Unique_keys  Boolean value. True if the return value
	   *  of _Hashtable::count(k) is always at most one, false if it may
	   *  be an arbitrary number. This is true for unordered_set and
	   *  unordered_map, false for unordered_multiset and
	   *  unordered_multimap.
	   */
	  template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
	    struct _Hashtable_traits
	    {
	      using __hash_cached = __bool_constant<_Cache_hash_code>;
	      using __constant_iterators = __bool_constant<_Constant_iterators>;
	      using __unique_keys = __bool_constant<_Unique_keys>;
	    };
	
	  /**
	   *  struct _Hash_node_base
	   *
	   *  Nodes, used to wrap elements stored in the hash table.  A policy
	   *  template parameter of class template _Hashtable controls whether
	   *  nodes also store a hash code. In some cases (e.g. strings) this
	   *  may be a performance win.
	   */
	  struct _Hash_node_base
	  {
	    _Hash_node_base* _M_nxt;
	
	    _Hash_node_base() noexcept : _M_nxt() { }
	
	    _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
	  };
	
	  /**
	   *  struct _Hash_node_value_base
	   *
	   *  Node type with the value to store.
	   */
	  template<typename _Value>
	    struct _Hash_node_value_base : _Hash_node_base
	    {
	      typedef _Value value_type;
	
	      __gnu_cxx::__aligned_buffer<_Value> _M_storage;
	
	      _Value*

	      _M_valptr() noexcept
	      { return _M_storage._M_ptr(); }
	
	      const _Value*
	      _M_valptr() const noexcept
	      { return _M_storage._M_ptr(); }
	
	      _Value&

	      _M_v() noexcept
	      { return *_M_valptr(); }
	
	      const _Value&
	      _M_v() const noexcept
	      { return *_M_valptr(); }
	    };
	
	  /**
	   *  Primary template struct _Hash_node.
	   */
	  template<typename _Value, bool _Cache_hash_code>
	    struct _Hash_node;
	
	  /**
	   *  Specialization for nodes with caches, struct _Hash_node.
	   *
	   *  Base class is __detail::_Hash_node_value_base.
	   */
	  template<typename _Value>
	    struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value>
	    {
	      std::size_t  _M_hash_code;
	
	      _Hash_node*
	      _M_next() const noexcept
	      { return static_cast<_Hash_node*>(this->_M_nxt); }
	    };
	
	  /**
	   *  Specialization for nodes without caches, struct _Hash_node.
	   *
	   *  Base class is __detail::_Hash_node_value_base.
	   */
	  template<typename _Value>
	    struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value>
	    {
	      _Hash_node*
	      _M_next() const noexcept
	      { return static_cast<_Hash_node*>(this->_M_nxt); }
	    };
	
	  /// Base class for node iterators.
	  template<typename _Value, bool _Cache_hash_code>
	    struct _Node_iterator_base
	    {
	      using __node_type = _Hash_node<_Value, _Cache_hash_code>;
	
	      __node_type*  _M_cur;
	
	      _Node_iterator_base(__node_type* __p) noexcept
	      : _M_cur(__p) { }
	
	      void
	      _M_incr() noexcept
	      { _M_cur = _M_cur->_M_next(); }
	    };
	
	  template<typename _Value, bool _Cache_hash_code>
	    inline bool
	    operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
		       const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
	    noexcept
	    { return __x._M_cur == __y._M_cur; }
	
	  template<typename _Value, bool _Cache_hash_code>
	    inline bool
	    operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
		       const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
	    noexcept
	    { return __x._M_cur != __y._M_cur; }
	
	  /// Node iterators, used to iterate through all the hashtable.
	  template<typename _Value, bool __constant_iterators, bool __cache>
	    struct _Node_iterator
	    : public _Node_iterator_base<_Value, __cache>
	    {
	    private:
	      using __base_type = _Node_iterator_base<_Value, __cache>;
	      using __node_type = typename __base_type::__node_type;
	
	    public:
	      typedef _Value					value_type;
	      typedef std::ptrdiff_t				difference_type;
	      typedef std::forward_iterator_tag			iterator_category;
	
	      using pointer = typename std::conditional<__constant_iterators,
							const _Value*, _Value*>::type;
	
	      using reference = typename std::conditional<__constant_iterators,
							  const _Value&, _Value&>::type;
	
	      _Node_iterator() noexcept
	      : __base_type(0) { }
	
	      explicit
	      _Node_iterator(__node_type* __p) noexcept
	      : __base_type(__p) { }
	
	      reference
	      operator*() const noexcept
	      { return this->_M_cur->_M_v(); }
	
	      pointer
	      operator->() const noexcept
	      { return this->_M_cur->_M_valptr(); }
	
	      _Node_iterator&
	      operator++() noexcept
	      {
		this->_M_incr();
		return *this;
	      }
	
	      _Node_iterator
	      operator++(int) noexcept
	      {
		_Node_iterator __tmp(*this);
		this->_M_incr();
		return __tmp;
	      }
	    };
	
	  /// Node const_iterators, used to iterate through all the hashtable.
	  template<typename _Value, bool __constant_iterators, bool __cache>
	    struct _Node_const_iterator
	    : public _Node_iterator_base<_Value, __cache>
	    {
	    private:
	      using __base_type = _Node_iterator_base<_Value, __cache>;
	      using __node_type = typename __base_type::__node_type;
	
	    public:
	      typedef _Value					value_type;
	      typedef std::ptrdiff_t				difference_type;
	      typedef std::forward_iterator_tag			iterator_category;
	
	      typedef const _Value*				pointer;
	      typedef const _Value&				reference;
	
	      _Node_const_iterator() noexcept
	      : __base_type(0) { }
	
	      explicit
	      _Node_const_iterator(__node_type* __p) noexcept
	      : __base_type(__p) { }
	
	      _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
				   __cache>& __x) noexcept
	      : __base_type(__x._M_cur) { }
	
	      reference
	      operator*() const noexcept
	      { return this->_M_cur->_M_v(); }
	
	      pointer
	      operator->() const noexcept
	      { return this->_M_cur->_M_valptr(); }
	
	      _Node_const_iterator&
	      operator++() noexcept
	      {
		this->_M_incr();
		return *this;
	      }
	
	      _Node_const_iterator
	      operator++(int) noexcept
	      {
		_Node_const_iterator __tmp(*this);
		this->_M_incr();
		return __tmp;
	      }
	    };
	
	  // Many of class template _Hashtable's template parameters are policy
	  // classes.  These are defaults for the policies.
	
	  /// Default range hashing function: use division to fold a large number
	  /// into the range [0, N).
	  struct _Mod_range_hashing
	  {
	    typedef std::size_t first_argument_type;
	    typedef std::size_t second_argument_type;
	    typedef std::size_t result_type;
	
	    result_type
	    operator()(first_argument_type __num,
		       second_argument_type __den) const noexcept
	    { return __num % __den; }
	  };
	
	  /// Default ranged hash function H.  In principle it should be a
	  /// function object composed from objects of type H1 and H2 such that
	  /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
	  /// h1 and h2.  So instead we'll just use a tag to tell class template
	  /// hashtable to do that composition.
	  struct _Default_ranged_hash { };
	
	  /// Default value for rehash policy.  Bucket size is (usually) the
	  /// smallest prime that keeps the load factor small enough.
	  struct _Prime_rehash_policy
	  {
	    using __has_load_factor = std::true_type;
	
	    _Prime_rehash_policy(float __z = 1.0) noexcept
	    : _M_max_load_factor(__z), _M_next_resize(0) { }
	
	    float
	    max_load_factor() const noexcept
	    { return _M_max_load_factor; }
	
	    // Return a bucket size no smaller than n.
	    std::size_t
	    _M_next_bkt(std::size_t __n) const;
	
	    // Return a bucket count appropriate for n elements
	    std::size_t
	    _M_bkt_for_elements(std::size_t __n) const
	    { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
	
	    // __n_bkt is current bucket count, __n_elt is current element count,
	    // and __n_ins is number of elements to be inserted.  Do we need to
	    // increase bucket count?  If so, return make_pair(true, n), where n
	    // is the new bucket count.  If not, return make_pair(false, 0).
	    std::pair<bool, std::size_t>
	    _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
			   std::size_t __n_ins) const;
	
	    typedef std::size_t _State;
	
	    _State
	    _M_state() const
	    { return _M_next_resize; }
	
	    void
	    _M_reset() noexcept
	    { _M_next_resize = 0; }
	
	    void
	    _M_reset(_State __state)
	    { _M_next_resize = __state; }
	
	    static const std::size_t _S_growth_factor = 2;
	
	    float		_M_max_load_factor;
	    mutable std::size_t	_M_next_resize;
	  };
	
	  /// Range hashing function assuming that second arg is a power of 2.
	  struct _Mask_range_hashing
	  {
	    typedef std::size_t first_argument_type;
	    typedef std::size_t second_argument_type;
	    typedef std::size_t result_type;
	
	    result_type
	    operator()(first_argument_type __num,
		       second_argument_type __den) const noexcept
	    { return __num & (__den - 1); }
	  };
	
	  /// Compute closest power of 2 not less than __n
	  inline std::size_t
	  __clp2(std::size_t __n) noexcept
	  {
	    // Equivalent to return __n ? std::ceil2(__n) : 0;
	    if (__n < 2)
	      return __n;
	    const unsigned __lz = sizeof(size_t) > sizeof(long)
	      ? __builtin_clzll(__n - 1ull)
	      : __builtin_clzl(__n - 1ul);
	    // Doing two shifts avoids undefined behaviour when __lz == 0.
	    return (size_t(1) << (numeric_limits<size_t>::digits - __lz - 1)) << 1;
	  }
	
	  /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
	  /// operations.
	  struct _Power2_rehash_policy
	  {
	    using __has_load_factor = std::true_type;
	
	    _Power2_rehash_policy(float __z = 1.0) noexcept
	    : _M_max_load_factor(__z), _M_next_resize(0) { }
	
	    float
	    max_load_factor() const noexcept
	    { return _M_max_load_factor; }
	
	    // Return a bucket size no smaller than n (as long as n is not above the
	    // highest power of 2).
	    std::size_t
	    _M_next_bkt(std::size_t __n) noexcept
	    {
	      const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
	      const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
	      std::size_t __res = __clp2(__n);
	
	      if (__res == __n)
		__res <<= 1;
	
	      if (__res == 0)
		__res = __max_bkt;
	
	      if (__res == __max_bkt)
		// Set next resize to the max value so that we never try to rehash again
		// as we already reach the biggest possible bucket number.
		// Note that it might result in max_load_factor not being respected.
		_M_next_resize = std::size_t(-1);
	      else
		_M_next_resize
		  = __builtin_ceil(__res * (long double)_M_max_load_factor);
	
	      return __res;
	    }
	
	    // Return a bucket count appropriate for n elements
	    std::size_t
	    _M_bkt_for_elements(std::size_t __n) const noexcept
	    { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
	
	    // __n_bkt is current bucket count, __n_elt is current element count,
	    // and __n_ins is number of elements to be inserted.  Do we need to
	    // increase bucket count?  If so, return make_pair(true, n), where n
	    // is the new bucket count.  If not, return make_pair(false, 0).
	    std::pair<bool, std::size_t>
	    _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
			   std::size_t __n_ins) noexcept
	    {
	      if (__n_elt + __n_ins >= _M_next_resize)
		{
		  long double __min_bkts = (__n_elt + __n_ins)
						/ (long double)_M_max_load_factor;
		  if (__min_bkts >= __n_bkt)
		    return std::make_pair(true,
		      _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
							__n_bkt * _S_growth_factor)));
	
		  _M_next_resize
		    = __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
		  return std::make_pair(false, 0);
		}
	      else
		return std::make_pair(false, 0);
	    }
	
	    typedef std::size_t _State;
	
	    _State
	    _M_state() const noexcept
	    { return _M_next_resize; }
	
	    void
	    _M_reset() noexcept
	    { _M_next_resize = 0; }
	
	    void
	    _M_reset(_State __state) noexcept
	    { _M_next_resize = __state; }
	
	    static const std::size_t _S_growth_factor = 2;
	
	    float	_M_max_load_factor;
	    std::size_t	_M_next_resize;
	  };
	
	  // Base classes for std::_Hashtable.  We define these base classes
	  // because in some cases we want to do different things depending on
	  // the value of a policy class.  In some cases the policy class
	  // affects which member functions and nested typedefs are defined;
	  // we handle that by specializing base class templates.  Several of
	  // the base class templates need to access other members of class
	  // template _Hashtable, so we use a variant of the "Curiously
	  // Recurring Template Pattern" (CRTP) technique.
	
	  /**
	   *  Primary class template _Map_base.
	   *
	   *  If the hashtable has a value type of the form pair<T1, T2> and a
	   *  key extraction policy (_ExtractKey) that returns the first part
	   *  of the pair, the hashtable gets a mapped_type typedef.  If it
	   *  satisfies those criteria and also has unique keys, then it also
	   *  gets an operator[].
	   */
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits,
		   bool _Unique_keys = _Traits::__unique_keys::value>
	    struct _Map_base { };
	
	  /// Partial specialization, __unique_keys set to false.
	  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
			     _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
	    {
	      using mapped_type = typename std::tuple_element<1, _Pair>::type;
	    };
	
	  /// Partial specialization, __unique_keys set to true.
	  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
			     _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
	    {
	    private:
	      using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
								 _Select1st,
								_Equal, _H1, _H2, _Hash,
								  _Traits>;
	
	      using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
					     _Select1st, _Equal,
					     _H1, _H2, _Hash, _RehashPolicy, _Traits>;
	
	      using __hash_code = typename __hashtable_base::__hash_code;
	      using __node_type = typename __hashtable_base::__node_type;
	
	    public:
	      using key_type = typename __hashtable_base::key_type;
	      using iterator = typename __hashtable_base::iterator;
	      using mapped_type = typename std::tuple_element<1, _Pair>::type;
	
	      mapped_type&
	      operator[](const key_type& __k);
	
	      mapped_type&
	      operator[](key_type&& __k);
	
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // DR 761. unordered_map needs an at() member function.
	      mapped_type&
	      at(const key_type& __k);
	
	      const mapped_type&
	      at(const key_type& __k) const;
	    };
	
	  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    auto
	    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
	    operator[](const key_type& __k)
	    -> mapped_type&
	    {
	      __hashtable* __h = static_cast<__hashtable*>(this);
	      __hash_code __code = __h->_M_hash_code(__k);
	      std::size_t __n = __h->_M_bucket_index(__k, __code);
	      __node_type* __p = __h->_M_find_node(__n, __k, __code);
	
	      if (!__p)
		{
		  __p = __h->_M_allocate_node(std::piecewise_construct,
					      std::tuple<const key_type&>(__k),
					      std::tuple<>());
		  return __h->_M_insert_unique_node(__n, __code, __p)->second;
		}
	
	      return __p->_M_v().second;
	    }
	
	  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    auto
	    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
	    operator[](key_type&& __k)
	    -> mapped_type&
	    {
	      __hashtable* __h = static_cast<__hashtable*>(this);
	      __hash_code __code = __h->_M_hash_code(__k);
	      std::size_t __n = __h->_M_bucket_index(__k, __code);
	      __node_type* __p = __h->_M_find_node(__n, __k, __code);
	
	      if (!__p)
		{
		  __p = __h->_M_allocate_node(std::piecewise_construct,
					      std::forward_as_tuple(std::move(__k)),
					      std::tuple<>());
		  return __h->_M_insert_unique_node(__n, __code, __p)->second;
		}
	
	      return __p->_M_v().second;
	    }
	
	  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    auto
	    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
	    at(const key_type& __k)
	    -> mapped_type&
	    {
	      __hashtable* __h = static_cast<__hashtable*>(this);
	      __hash_code __code = __h->_M_hash_code(__k);
	      std::size_t __n = __h->_M_bucket_index(__k, __code);
	      __node_type* __p = __h->_M_find_node(__n, __k, __code);
	
	      if (!__p)
		__throw_out_of_range(__N("_Map_base::at"));
	      return __p->_M_v().second;
	    }
	
	  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    auto
	    _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
	    at(const key_type& __k) const
	    -> const mapped_type&
	    {
	      const __hashtable* __h = static_cast<const __hashtable*>(this);
	      __hash_code __code = __h->_M_hash_code(__k);
	      std::size_t __n = __h->_M_bucket_index(__k, __code);
	      __node_type* __p = __h->_M_find_node(__n, __k, __code);
	
	      if (!__p)
		__throw_out_of_range(__N("_Map_base::at"));
	      return __p->_M_v().second;
	    }
	
	  /**
	   *  Primary class template _Insert_base.
	   *
	   *  Defines @c insert member functions appropriate to all _Hashtables.
	   */
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Insert_base
	    {
	    protected:
	      using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
					     _Equal, _H1, _H2, _Hash,
					     _RehashPolicy, _Traits>;
	
	      using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
						       _Equal, _H1, _H2, _Hash,
						       _Traits>;
	
	      using value_type = typename __hashtable_base::value_type;
	      using iterator = typename __hashtable_base::iterator;
	      using const_iterator =  typename __hashtable_base::const_iterator;
	      using size_type = typename __hashtable_base::size_type;
	
	      using __unique_keys = typename __hashtable_base::__unique_keys;
	      using __ireturn_type = typename __hashtable_base::__ireturn_type;
	      using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>;
	      using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
	      using __node_gen_type = _AllocNode<__node_alloc_type>;
	
	      __hashtable&
	      _M_conjure_hashtable()
	      { return *(static_cast<__hashtable*>(this)); }
	
	      template<typename _InputIterator, typename _NodeGetter>
		void
		_M_insert_range(_InputIterator __first, _InputIterator __last,
				const _NodeGetter&, true_type);
	
	      template<typename _InputIterator, typename _NodeGetter>
		void
		_M_insert_range(_InputIterator __first, _InputIterator __last,
				const _NodeGetter&, false_type);
	
	    public:
	      __ireturn_type
	      insert(const value_type& __v)
	      {
		__hashtable& __h = _M_conjure_hashtable();
		__node_gen_type __node_gen(__h);
		return __h._M_insert(__v, __node_gen, __unique_keys());
	      }
	
	      iterator
	      insert(const_iterator __hint, const value_type& __v)
	      {
		__hashtable& __h = _M_conjure_hashtable();
		__node_gen_type __node_gen(__h);	
		return __h._M_insert(__hint, __v, __node_gen, __unique_keys());
	      }
	
	      void
	      insert(initializer_list<value_type> __l)
	      { this->insert(__l.begin(), __l.end()); }
	
	      template<typename _InputIterator>
		void
		insert(_InputIterator __first, _InputIterator __last)
		{
		  __hashtable& __h = _M_conjure_hashtable();
		  __node_gen_type __node_gen(__h);
		  return _M_insert_range(__first, __last, __node_gen, __unique_keys());
		}
	    };
	
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    template<typename _InputIterator, typename _NodeGetter>
	      void
	      _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
			    _RehashPolicy, _Traits>::
	      _M_insert_range(_InputIterator __first, _InputIterator __last,
			      const _NodeGetter& __node_gen, true_type)
	      {
		size_type __n_elt = __detail::__distance_fw(__first, __last);
		if (__n_elt == 0)
		  return;
	
		__hashtable& __h = _M_conjure_hashtable();
		for (; __first != __last; ++__first)
		  {
		    if (__h._M_insert(*__first, __node_gen, __unique_keys(),
				      __n_elt).second)
		      __n_elt = 1;
		    else if (__n_elt != 1)
		      --__n_elt;
		  }
	      }
	
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    template<typename _InputIterator, typename _NodeGetter>
	      void
	      _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
			    _RehashPolicy, _Traits>::
	      _M_insert_range(_InputIterator __first, _InputIterator __last,
			      const _NodeGetter& __node_gen, false_type)
	      {
		using __rehash_type = typename __hashtable::__rehash_type;
		using __rehash_state = typename __hashtable::__rehash_state;
		using pair_type = std::pair<bool, std::size_t>;
	
		size_type __n_elt = __detail::__distance_fw(__first, __last);
		if (__n_elt == 0)
		  return;
	
		__hashtable& __h = _M_conjure_hashtable();
		__rehash_type& __rehash = __h._M_rehash_policy;
		const __rehash_state& __saved_state = __rehash._M_state();
		pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
								__h._M_element_count,
								__n_elt);
	
		if (__do_rehash.first)
		  __h._M_rehash(__do_rehash.second, __saved_state);
	
		for (; __first != __last; ++__first)
		  __h._M_insert(*__first, __node_gen, __unique_keys());
	      }
	
	  /**
	   *  Primary class template _Insert.
	   *
	   *  Defines @c insert member functions that depend on _Hashtable policies,
	   *  via partial specializations.
	   */
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits,
		   bool _Constant_iterators = _Traits::__constant_iterators::value>
	    struct _Insert;
	
	  /// Specialization.
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
			   _RehashPolicy, _Traits, true>
	    : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
				   _H1, _H2, _Hash, _RehashPolicy, _Traits>
	    {
	      using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
						_Equal, _H1, _H2, _Hash,
						_RehashPolicy, _Traits>;
	
	      using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
						       _Equal, _H1, _H2, _Hash,
						       _Traits>;
	
	      using value_type = typename __base_type::value_type;
	      using iterator = typename __base_type::iterator;
	      using const_iterator =  typename __base_type::const_iterator;
	
	      using __unique_keys = typename __base_type::__unique_keys;
	      using __ireturn_type = typename __hashtable_base::__ireturn_type;
	      using __hashtable = typename __base_type::__hashtable;
	      using __node_gen_type = typename __base_type::__node_gen_type;
	
	      using __base_type::insert;
	
	      __ireturn_type
	      insert(value_type&& __v)
	      {
		__hashtable& __h = this->_M_conjure_hashtable();
		__node_gen_type __node_gen(__h);
		return __h._M_insert(std::move(__v), __node_gen, __unique_keys());
	      }
	
	      iterator
	      insert(const_iterator __hint, value_type&& __v)
	      {
		__hashtable& __h = this->_M_conjure_hashtable();
		__node_gen_type __node_gen(__h);
		return __h._M_insert(__hint, std::move(__v), __node_gen,
				     __unique_keys());
	      }
	    };
	
	  /// Specialization.
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
			   _RehashPolicy, _Traits, false>
	    : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
				   _H1, _H2, _Hash, _RehashPolicy, _Traits>
	    {
	      using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
					       _Equal, _H1, _H2, _Hash,
					       _RehashPolicy, _Traits>;
	      using value_type = typename __base_type::value_type;
	      using iterator = typename __base_type::iterator;
	      using const_iterator =  typename __base_type::const_iterator;
	
	      using __unique_keys = typename __base_type::__unique_keys;
	      using __hashtable = typename __base_type::__hashtable;
	      using __ireturn_type = typename __base_type::__ireturn_type;
	
	      using __base_type::insert;
	
	      template<typename _Pair>
		using __is_cons = std::is_constructible<value_type, _Pair&&>;
	
	      template<typename _Pair>
		using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
	
	      template<typename _Pair>
		using _IFconsp = typename _IFcons<_Pair>::type;
	
	      template<typename _Pair, typename = _IFconsp<_Pair>>
		__ireturn_type
		insert(_Pair&& __v)
		{
		  __hashtable& __h = this->_M_conjure_hashtable();
		  return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
		}
	
	      template<typename _Pair, typename = _IFconsp<_Pair>>
		iterator
		insert(const_iterator __hint, _Pair&& __v)
		{
		  __hashtable& __h = this->_M_conjure_hashtable();
		  return __h._M_emplace(__hint, __unique_keys(),
					std::forward<_Pair>(__v));
		}
	   };
	
	  template<typename _Policy>
	    using __has_load_factor = typename _Policy::__has_load_factor;
	
	  /**
	   *  Primary class template  _Rehash_base.
	   *
	   *  Give hashtable the max_load_factor functions and reserve iff the
	   *  rehash policy supports it.
	  */
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits,
		   typename =
		     __detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>>
	    struct _Rehash_base;
	
	  /// Specialization when rehash policy doesn't provide load factor management.
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
			      _H1, _H2, _Hash, _RehashPolicy, _Traits,
			      std::false_type>
	    {
	    };
	
	  /// Specialization when rehash policy provide load factor management.
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
				_H1, _H2, _Hash, _RehashPolicy, _Traits,
				std::true_type>
	    {
	      using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
					     _Equal, _H1, _H2, _Hash,
					     _RehashPolicy, _Traits>;
	
	      float
	      max_load_factor() const noexcept
	      {
		const __hashtable* __this = static_cast<const __hashtable*>(this);
		return __this->__rehash_policy().max_load_factor();
	      }
	
	      void
	      max_load_factor(float __z)
	      {
		__hashtable* __this = static_cast<__hashtable*>(this);
		__this->__rehash_policy(_RehashPolicy(__z));
	      }
	
	      void
	      reserve(std::size_t __n)
	      {
		__hashtable* __this = static_cast<__hashtable*>(this);
		__this->rehash(__builtin_ceil(__n / max_load_factor()));
	      }
	    };
	
	  /**
	   *  Primary class template _Hashtable_ebo_helper.
	   *
	   *  Helper class using EBO when it is not forbidden (the type is not
	   *  final) and when it is worth it (the type is empty.)
	   */
	  template<int _Nm, typename _Tp,
		   bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
	    struct _Hashtable_ebo_helper;
	
	  /// Specialization using EBO.
	  template<int _Nm, typename _Tp>
	    struct _Hashtable_ebo_helper<_Nm, _Tp, true>
	    : private _Tp
	    {
	      _Hashtable_ebo_helper() = default;
	
	      template<typename _OtherTp>
		_Hashtable_ebo_helper(_OtherTp&& __tp)
		  : _Tp(std::forward<_OtherTp>(__tp))
		{ }
	
	      static const _Tp&
	      _S_cget(const _Hashtable_ebo_helper& __eboh)
	      { return static_cast<const _Tp&>(__eboh); }
	
	      static _Tp&
	      _S_get(_Hashtable_ebo_helper& __eboh)
	      { return static_cast<_Tp&>(__eboh); }
	    };
	
	  /// Specialization not using EBO.
	  template<int _Nm, typename _Tp>
	    struct _Hashtable_ebo_helper<_Nm, _Tp, false>
	    {
	      _Hashtable_ebo_helper() = default;
	
	      template<typename _OtherTp>
		_Hashtable_ebo_helper(_OtherTp&& __tp)
		  : _M_tp(std::forward<_OtherTp>(__tp))
		{ }
	
	      static const _Tp&
	      _S_cget(const _Hashtable_ebo_helper& __eboh)
	      { return __eboh._M_tp; }
	
	      static _Tp&
	      _S_get(_Hashtable_ebo_helper& __eboh)
	      { return __eboh._M_tp; }
	
	    private:
	      _Tp _M_tp;
	    };
	
	  /**
	   *  Primary class template _Local_iterator_base.
	   *
	   *  Base class for local iterators, used to iterate within a bucket
	   *  but not between buckets.
	   */
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash,
		   bool __cache_hash_code>
	    struct _Local_iterator_base;
	
	  /**
	   *  Primary class template _Hash_code_base.
	   *
	   *  Encapsulates two policy issues that aren't quite orthogonal.
	   *   (1) the difference between using a ranged hash function and using
	   *       the combination of a hash function and a range-hashing function.
	   *       In the former case we don't have such things as hash codes, so
	   *       we have a dummy type as placeholder.
	   *   (2) Whether or not we cache hash codes.  Caching hash codes is
	   *       meaningless if we have a ranged hash function.
	   *
	   *  We also put the key extraction objects here, for convenience.
	   *  Each specialization derives from one or more of the template
	   *  parameters to benefit from Ebo. This is important as this type
	   *  is inherited in some cases by the _Local_iterator_base type used
	   *  to implement local_iterator and const_local_iterator. As with
	   *  any iterator type we prefer to make it as small as possible.
	   *
	   *  Primary template is unused except as a hook for specializations.
	   */
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash,
		   bool __cache_hash_code>
	    struct _Hash_code_base;
	
	  /// Specialization: ranged hash function, no caching hash codes.  H1
	  /// and H2 are provided but ignored.  We define a dummy hash code type.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash>
	    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
	    : private _Hashtable_ebo_helper<0, _ExtractKey>,
	      private _Hashtable_ebo_helper<1, _Hash>
	    {
	    private:
	      using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
	      using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
	
	    protected:
	      typedef void* 					__hash_code;
	      typedef _Hash_node<_Value, false>			__node_type;
	
	      // We need the default constructor for the local iterators and _Hashtable
	      // default constructor.
	      _Hash_code_base() = default;
	
	      _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
			      const _Hash& __h)
	      : __ebo_extract_key(__ex), __ebo_hash(__h) { }
	
	      __hash_code
	      _M_hash_code(const _Key& __key) const
	      { return 0; }
	
	      std::size_t
	      _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
	      { return _M_ranged_hash()(__k, __n); }
	
	      std::size_t
	      _M_bucket_index(const __node_type* __p, std::size_t __n) const
		noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(),
							   (std::size_t)0)) )
	      { return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); }
	
	      void
	      _M_store_code(__node_type*, __hash_code) const
	      { }
	
	      void
	      _M_copy_code(__node_type*, const __node_type*) const
	      { }
	
	      void
	      _M_swap(_Hash_code_base& __x)
	      {
		std::swap(_M_extract(), __x._M_extract());
		std::swap(_M_ranged_hash(), __x._M_ranged_hash());
	      }
	
	      const _ExtractKey&
	      _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
	
	      _ExtractKey&
	      _M_extract() { return __ebo_extract_key::_S_get(*this); }
	
	      const _Hash&
	      _M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }
	
	      _Hash&
	      _M_ranged_hash() { return __ebo_hash::_S_get(*this); }
	    };
	
	  // No specialization for ranged hash function while caching hash codes.
	  // That combination is meaningless, and trying to do it is an error.
	
	  /// Specialization: ranged hash function, cache hash codes.  This
	  /// combination is meaningless, so we provide only a declaration
	  /// and no definition.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash>
	    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
	
	  /// Specialization: hash function and range-hashing function, no
	  /// caching of hash codes.
	  /// Provides typedef and accessor required by C++ 11.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2>
	    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
				   _Default_ranged_hash, false>
	    : private _Hashtable_ebo_helper<0, _ExtractKey>,
	      private _Hashtable_ebo_helper<1, _H1>,
	      private _Hashtable_ebo_helper<2, _H2>
	    {
	    private:
	      using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
	      using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
	      using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
	
	      // Gives the local iterator implementation access to _M_bucket_index().
	      friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
						 _Default_ranged_hash, false>;
	
	    public:
	      typedef _H1 					hasher;
	
	      hasher
	      hash_function() const
	      { return _M_h1(); }
	
	    protected:
	      typedef std::size_t 				__hash_code;
	      typedef _Hash_node<_Value, false>			__node_type;
	
	      // We need the default constructor for the local iterators and _Hashtable
	      // default constructor.
	      _Hash_code_base() = default;
	
	      _Hash_code_base(const _ExtractKey& __ex,
			      const _H1& __h1, const _H2& __h2,
			      const _Default_ranged_hash&)
	      : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
	
	      __hash_code
	      _M_hash_code(const _Key& __k) const
	      {
		static_assert(__is_invocable<const _H1&, const _Key&>{},
		    "hash function must be invocable with an argument of key type");
		return _M_h1()(__k);
	      }
	
	      std::size_t
	      _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
	      { return _M_h2()(__c, __n); }
	
	      std::size_t
	      _M_bucket_index(const __node_type* __p, std::size_t __n) const
		noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>()))
			  && noexcept(declval<const _H2&>()((__hash_code)0,
							    (std::size_t)0)) )
	      { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); }
	
	      void
	      _M_store_code(__node_type*, __hash_code) const
	      { }
	
	      void
	      _M_copy_code(__node_type*, const __node_type*) const
	      { }
	
	      void
	      _M_swap(_Hash_code_base& __x)
	      {
		std::swap(_M_extract(), __x._M_extract());
		std::swap(_M_h1(), __x._M_h1());
		std::swap(_M_h2(), __x._M_h2());
	      }
	
	      const _ExtractKey&
	      _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
	
	      _ExtractKey&
	      _M_extract() { return __ebo_extract_key::_S_get(*this); }
	
	      const _H1&
	      _M_h1() const { return __ebo_h1::_S_cget(*this); }
	
	      _H1&
	      _M_h1() { return __ebo_h1::_S_get(*this); }
	
	      const _H2&
	      _M_h2() const { return __ebo_h2::_S_cget(*this); }
	
	      _H2&
	      _M_h2() { return __ebo_h2::_S_get(*this); }
	    };
	
	  /// Specialization: hash function and range-hashing function,
	  /// caching hash codes.  H is provided but ignored.  Provides
	  /// typedef and accessor required by C++ 11.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2>
	    struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
				   _Default_ranged_hash, true>
	    : private _Hashtable_ebo_helper<0, _ExtractKey>,
	      private _Hashtable_ebo_helper<1, _H1>,
	      private _Hashtable_ebo_helper<2, _H2>
	    {
	    private:
	      // Gives the local iterator implementation access to _M_h2().
	      friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
						 _Default_ranged_hash, true>;
	
	      using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
	      using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
	      using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
	
	    public:
	      typedef _H1 					hasher;
	
	      hasher
	      hash_function() const
	      { return _M_h1(); }
	
	    protected:
	      typedef std::size_t 				__hash_code;
	      typedef _Hash_node<_Value, true>			__node_type;
	
	      // We need the default constructor for _Hashtable default constructor.
	      _Hash_code_base() = default;
	      _Hash_code_base(const _ExtractKey& __ex,
			      const _H1& __h1, const _H2& __h2,
			      const _Default_ranged_hash&)
	      : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
	
	      __hash_code
	      _M_hash_code(const _Key& __k) const
	      {
		static_assert(__is_invocable<const _H1&, const _Key&>{},
		    "hash function must be invocable with an argument of key type");
		return _M_h1()(__k);
	      }
	
	      std::size_t
	      _M_bucket_index(const _Key&, __hash_code __c,
			      std::size_t __n) const
	      { return _M_h2()(__c, __n); }
	
	      std::size_t
	      _M_bucket_index(const __node_type* __p, std::size_t __n) const
		noexcept( noexcept(declval<const _H2&>()((__hash_code)0,
							 (std::size_t)0)) )
	      { return _M_h2()(__p->_M_hash_code, __n); }
	
	      void
	      _M_store_code(__node_type* __n, __hash_code __c) const
	      { __n->_M_hash_code = __c; }
	
	      void
	      _M_copy_code(__node_type* __to, const __node_type* __from) const
	      { __to->_M_hash_code = __from->_M_hash_code; }
	
	      void
	      _M_swap(_Hash_code_base& __x)
	      {
		std::swap(_M_extract(), __x._M_extract());
		std::swap(_M_h1(), __x._M_h1());
		std::swap(_M_h2(), __x._M_h2());
	      }
	
	      const _ExtractKey&
	      _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
	
	      _ExtractKey&
	      _M_extract() { return __ebo_extract_key::_S_get(*this); }
	
	      const _H1&
	      _M_h1() const { return __ebo_h1::_S_cget(*this); }
	
	      _H1&
	      _M_h1() { return __ebo_h1::_S_get(*this); }
	
	      const _H2&
	      _M_h2() const { return __ebo_h2::_S_cget(*this); }
	
	      _H2&
	      _M_h2() { return __ebo_h2::_S_get(*this); }
	    };
	
	  /**
	   *  Primary class template _Equal_helper.
	   *
	   */
	  template <typename _Key, typename _Value, typename _ExtractKey,
		    typename _Equal, typename _HashCodeType,
		    bool __cache_hash_code>
	  struct _Equal_helper;
	
	  /// Specialization.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _Equal, typename _HashCodeType>
	  struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
	  {
	    static bool
	    _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
		      const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
	    { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); }
	  };
	
	  /// Specialization.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _Equal, typename _HashCodeType>
	  struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
	  {
	    static bool
	    _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
		      const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
	    { return __eq(__k, __extract(__n->_M_v())); }
	  };
	
	
	  /// Partial specialization used when nodes contain a cached hash code.
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash>
	    struct _Local_iterator_base<_Key, _Value, _ExtractKey,
					_H1, _H2, _Hash, true>
	    : private _Hashtable_ebo_helper<0, _H2>
	    {
	    protected:
	      using __base_type = _Hashtable_ebo_helper<0, _H2>;
	      using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
						       _H1, _H2, _Hash, true>;
	
	      _Local_iterator_base() = default;
	      _Local_iterator_base(const __hash_code_base& __base,
				   _Hash_node<_Value, true>* __p,
				   std::size_t __bkt, std::size_t __bkt_count)
	      : __base_type(__base._M_h2()),
		_M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
	
	      void
	      _M_incr()
	      {
		_M_cur = _M_cur->_M_next();
		if (_M_cur)
		  {
		    std::size_t __bkt
		      = __base_type::_S_get(*this)(_M_cur->_M_hash_code,
						   _M_bucket_count);
		    if (__bkt != _M_bucket)
		      _M_cur = nullptr;
		  }
	      }
	
	      _Hash_node<_Value, true>*  _M_cur;
	      std::size_t _M_bucket;
	      std::size_t _M_bucket_count;
	
	    public:
	      const void*
	      _M_curr() const { return _M_cur; }  // for equality ops
	
	      std::size_t
	      _M_get_bucket() const { return _M_bucket; }  // for debug mode
	    };
	
	  // Uninitialized storage for a _Hash_code_base.
	  // This type is DefaultConstructible and Assignable even if the
	  // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
	  // can be DefaultConstructible and Assignable.
	  template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
	    struct _Hash_code_storage
	    {
	      __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
	
	      _Tp*
	      _M_h() { return _M_storage._M_ptr(); }
	
	      const _Tp*
	      _M_h() const { return _M_storage._M_ptr(); }
	    };
	
	  // Empty partial specialization for empty _Hash_code_base types.
	  template<typename _Tp>
	    struct _Hash_code_storage<_Tp, true>
	    {
	      static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
	
	      // As _Tp is an empty type there will be no bytes written/read through
	      // the cast pointer, so no strict-aliasing violation.
	      _Tp*
	      _M_h() { return reinterpret_cast<_Tp*>(this); }
	
	      const _Tp*
	      _M_h() const { return reinterpret_cast<const _Tp*>(this); }
	    };
	
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash>
	    using __hash_code_for_local_iter
	      = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
						   _H1, _H2, _Hash, false>>;
	
	  // Partial specialization used when hash codes are not cached
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash>
	    struct _Local_iterator_base<_Key, _Value, _ExtractKey,
					_H1, _H2, _Hash, false>
	    : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash>
	    {
	    protected:
	      using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
						       _H1, _H2, _Hash, false>;
	
	      _Local_iterator_base() : _M_bucket_count(-1) { }
	
	      _Local_iterator_base(const __hash_code_base& __base,
				   _Hash_node<_Value, false>* __p,
				   std::size_t __bkt, std::size_t __bkt_count)
	      : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
	      { _M_init(__base); }
	
	      ~_Local_iterator_base()
	      {
		if (_M_bucket_count != -1)
		  _M_destroy();
	      }
	
	      _Local_iterator_base(const _Local_iterator_base& __iter)
	      : _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket),
	        _M_bucket_count(__iter._M_bucket_count)
	      {
		if (_M_bucket_count != -1)
		  _M_init(*__iter._M_h());
	      }
	
	      _Local_iterator_base&
	      operator=(const _Local_iterator_base& __iter)
	      {
		if (_M_bucket_count != -1)
		  _M_destroy();
		_M_cur = __iter._M_cur;
		_M_bucket = __iter._M_bucket;
		_M_bucket_count = __iter._M_bucket_count;
		if (_M_bucket_count != -1)
		  _M_init(*__iter._M_h());
		return *this;
	      }
	
	      void
	      _M_incr()
	      {
		_M_cur = _M_cur->_M_next();
		if (_M_cur)
		  {
		    std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur,
								      _M_bucket_count);
		    if (__bkt != _M_bucket)
		      _M_cur = nullptr;
		  }
	      }
	
	      _Hash_node<_Value, false>*  _M_cur;
	      std::size_t _M_bucket;
	      std::size_t _M_bucket_count;
	
	      void
	      _M_init(const __hash_code_base& __base)
	      { ::new(this->_M_h()) __hash_code_base(__base); }
	
	      void
	      _M_destroy() { this->_M_h()->~__hash_code_base(); }
	
	    public:
	      const void*
	      _M_curr() const { return _M_cur; }  // for equality ops and debug mode
	
	      std::size_t
	      _M_get_bucket() const { return _M_bucket; }  // for debug mode
	    };
	
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash, bool __cache>
	    inline bool
	    operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
						  _H1, _H2, _Hash, __cache>& __x,
		       const _Local_iterator_base<_Key, _Value, _ExtractKey,
						  _H1, _H2, _Hash, __cache>& __y)
	    { return __x._M_curr() == __y._M_curr(); }
	
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash, bool __cache>
	    inline bool
	    operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
						  _H1, _H2, _Hash, __cache>& __x,
		       const _Local_iterator_base<_Key, _Value, _ExtractKey,
						  _H1, _H2, _Hash, __cache>& __y)
	    { return __x._M_curr() != __y._M_curr(); }
	
	  /// local iterators
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash,
		   bool __constant_iterators, bool __cache>
	    struct _Local_iterator
	    : public _Local_iterator_base<_Key, _Value, _ExtractKey,
					  _H1, _H2, _Hash, __cache>
	    {
	    private:
	      using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
						       _H1, _H2, _Hash, __cache>;
	      using __hash_code_base = typename __base_type::__hash_code_base;
	    public:
	      typedef _Value					value_type;
	      typedef typename std::conditional<__constant_iterators,
						const _Value*, _Value*>::type
							       pointer;
	      typedef typename std::conditional<__constant_iterators,
						const _Value&, _Value&>::type
							       reference;
	      typedef std::ptrdiff_t				difference_type;
	      typedef std::forward_iterator_tag			iterator_category;
	
	      _Local_iterator() = default;
	
	      _Local_iterator(const __hash_code_base& __base,
			      _Hash_node<_Value, __cache>* __p,
			      std::size_t __bkt, std::size_t __bkt_count)
		: __base_type(__base, __p, __bkt, __bkt_count)
	      { }
	
	      reference
	      operator*() const
	      { return this->_M_cur->_M_v(); }
	
	      pointer
	      operator->() const
	      { return this->_M_cur->_M_valptr(); }
	
	      _Local_iterator&
	      operator++()
	      {
		this->_M_incr();
		return *this;
	      }
	
	      _Local_iterator
	      operator++(int)
	      {
		_Local_iterator __tmp(*this);
		this->_M_incr();
		return __tmp;
	      }
	    };
	
	  /// local const_iterators
	  template<typename _Key, typename _Value, typename _ExtractKey,
		   typename _H1, typename _H2, typename _Hash,
		   bool __constant_iterators, bool __cache>
	    struct _Local_const_iterator
	    : public _Local_iterator_base<_Key, _Value, _ExtractKey,
					  _H1, _H2, _Hash, __cache>
	    {
	    private:
	      using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
						       _H1, _H2, _Hash, __cache>;
	      using __hash_code_base = typename __base_type::__hash_code_base;
	
	    public:
	      typedef _Value					value_type;
	      typedef const _Value*				pointer;
	      typedef const _Value&				reference;
	      typedef std::ptrdiff_t				difference_type;
	      typedef std::forward_iterator_tag			iterator_category;
	
	      _Local_const_iterator() = default;
	
	      _Local_const_iterator(const __hash_code_base& __base,
				    _Hash_node<_Value, __cache>* __p,
				    std::size_t __bkt, std::size_t __bkt_count)
		: __base_type(__base, __p, __bkt, __bkt_count)
	      { }
	
	      _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
							  _H1, _H2, _Hash,
							  __constant_iterators,
							  __cache>& __x)
		: __base_type(__x)
	      { }
	
	      reference
	      operator*() const
	      { return this->_M_cur->_M_v(); }
	
	      pointer
	      operator->() const
	      { return this->_M_cur->_M_valptr(); }
	
	      _Local_const_iterator&
	      operator++()
	      {
		this->_M_incr();
		return *this;
	      }
	
	      _Local_const_iterator
	      operator++(int)
	      {
		_Local_const_iterator __tmp(*this);
		this->_M_incr();
		return __tmp;
	      }
	    };
	
	  /**
	   *  Primary class template _Hashtable_base.
	   *
	   *  Helper class adding management of _Equal functor to
	   *  _Hash_code_base type.
	   *
	   *  Base class templates are:
	   *    - __detail::_Hash_code_base
	   *    - __detail::_Hashtable_ebo_helper
	   */
	  template<typename _Key, typename _Value,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash, typename _Traits>
	  struct _Hashtable_base
	  : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
				   _Traits::__hash_cached::value>,
	    private _Hashtable_ebo_helper<0, _Equal>
	  {
	  public:
	    typedef _Key					key_type;
	    typedef _Value					value_type;
	    typedef _Equal					key_equal;
	    typedef std::size_t					size_type;
	    typedef std::ptrdiff_t				difference_type;
	
	    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 __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
						     _H1, _H2, _Hash,
						     __hash_cached::value>;
	
	    using __hash_code = typename __hash_code_base::__hash_code;
	    using __node_type = typename __hash_code_base::__node_type;
	
	    using iterator = __detail::_Node_iterator<value_type,
						      __constant_iterators::value,
						      __hash_cached::value>;
	
	    using const_iterator = __detail::_Node_const_iterator<value_type,
							   __constant_iterators::value,
							   __hash_cached::value>;
	
	    using local_iterator = __detail::_Local_iterator<key_type, value_type,
							  _ExtractKey, _H1, _H2, _Hash,
							  __constant_iterators::value,
							     __hash_cached::value>;
	
	    using const_local_iterator = __detail::_Local_const_iterator<key_type,
									 value_type,
						_ExtractKey, _H1, _H2, _Hash,
						__constant_iterators::value,
						__hash_cached::value>;
	
	    using __ireturn_type = typename std::conditional<__unique_keys::value,
							     std::pair<iterator, bool>,
							     iterator>::type;
	  private:
	    using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
	    using _EqualHelper =  _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
						__hash_code, __hash_cached::value>;
	
	  protected:
	    _Hashtable_base() = default;
	    _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
			    const _Hash& __hash, const _Equal& __eq)
	    : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
	    { }
	
	    bool
	    _M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
	    {
	      static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
		  "key equality predicate must be invocable with two arguments of "
		  "key type");
	      return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
					     __k, __c, __n);
	    }
	
	    void
	    _M_swap(_Hashtable_base& __x)
	    {
	      __hash_code_base::_M_swap(__x);
	      std::swap(_M_eq(), __x._M_eq());
	    }
	
	    const _Equal&
	    _M_eq() const { return _EqualEBO::_S_cget(*this); }
	
	    _Equal&
	    _M_eq() { return _EqualEBO::_S_get(*this); }
	  };
	
	  /**
	   *  struct _Equality_base.
	   *
	   *  Common types and functions for class _Equality.
	   */
	  struct _Equality_base
	  {
	  protected:
	    template<typename _Uiterator>
	      static bool
	      _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
	  };
	
	  // See std::is_permutation in N3068.
	  template<typename _Uiterator>
	    bool
	    _Equality_base::
	    _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
			      _Uiterator __first2)
	    {
	      for (; __first1 != __last1; ++__first1, ++__first2)
		if (!(*__first1 == *__first2))
		  break;
	
	      if (__first1 == __last1)
		return true;
	
	      _Uiterator __last2 = __first2;
	      std::advance(__last2, std::distance(__first1, __last1));
	
	      for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
		{
		  _Uiterator __tmp =  __first1;
		  while (__tmp != __it1 && !bool(*__tmp == *__it1))
		    ++__tmp;
	
		  // We've seen this one before.
		  if (__tmp != __it1)
		    continue;
	
		  std::ptrdiff_t __n2 = 0;
		  for (__tmp = __first2; __tmp != __last2; ++__tmp)
		    if (*__tmp == *__it1)
		      ++__n2;
	
		  if (!__n2)
		    return false;
	
		  std::ptrdiff_t __n1 = 0;
		  for (__tmp = __it1; __tmp != __last1; ++__tmp)
		    if (*__tmp == *__it1)
		      ++__n1;
	
		  if (__n1 != __n2)
		    return false;
		}
	      return true;
	    }
	
	  /**
	   *  Primary class template  _Equality.
	   *
	   *  This is for implementing equality comparison for unordered
	   *  containers, per N3068, by John Lakos and Pablo Halpern.
	   *  Algorithmically, we follow closely the reference implementations
	   *  therein.
	   */
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits,
		   bool _Unique_keys = _Traits::__unique_keys::value>
	    struct _Equality;
	
	  /// Specialization.
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
			     _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
	    {
	      using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
					     _H1, _H2, _Hash, _RehashPolicy, _Traits>;
	
	      bool
	      _M_equal(const __hashtable&) const;
	    };
	
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    bool
	    _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
	    _M_equal(const __hashtable& __other) const
	    {
	      const __hashtable* __this = static_cast<const __hashtable*>(this);
	
	      if (__this->size() != __other.size())
		return false;
	
	      for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
		{
		  const auto __ity = __other.find(_ExtractKey()(*__itx));
		  if (__ity == __other.end() || !bool(*__ity == *__itx))
		    return false;
		}
	      return true;
	    }
	
	  /// Specialization.
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
			     _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
	    : public _Equality_base
	    {
	      using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
					     _H1, _H2, _Hash, _RehashPolicy, _Traits>;
	
	      bool
	      _M_equal(const __hashtable&) const;
	    };
	
	  template<typename _Key, typename _Value, typename _Alloc,
		   typename _ExtractKey, typename _Equal,
		   typename _H1, typename _H2, typename _Hash,
		   typename _RehashPolicy, typename _Traits>
	    bool
	    _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
		      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
	    _M_equal(const __hashtable& __other) const
	    {
	      const __hashtable* __this = static_cast<const __hashtable*>(this);
	
	      if (__this->size() != __other.size())
		return false;
	
	      for (auto __itx = __this->begin(); __itx != __this->end();)
		{
		  const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
		  const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
	
		  if (std::distance(__xrange.first, __xrange.second)
		      != std::distance(__yrange.first, __yrange.second))
		    return false;
	
		  if (!_S_is_permutation(__xrange.first, __xrange.second,
					 __yrange.first))
		    return false;
	
		  __itx = __xrange.second;
		}
	      return true;
	    }
	
	  /**
	   * This type deals with all allocation and keeps an allocator instance through
	   * inheritance to benefit from EBO when possible.
	   */
	  template<typename _NodeAlloc>
	    struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
	    {
	    private:
	      using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
	    public:
	      using __node_type = typename _NodeAlloc::value_type;
	      using __node_alloc_type = _NodeAlloc;
	      // Use __gnu_cxx to benefit from _S_always_equal and al.
	      using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
	
	      using __value_alloc_traits = typename __node_alloc_traits::template
		rebind_traits<typename __node_type::value_type>;
	
	      using __node_base = __detail::_Hash_node_base;
	      using __bucket_type = __node_base*;      
	      using __bucket_alloc_type =
		__alloc_rebind<__node_alloc_type, __bucket_type>;
	      using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>;
	
	      _Hashtable_alloc() = default;
	      _Hashtable_alloc(const _Hashtable_alloc&) = default;
	      _Hashtable_alloc(_Hashtable_alloc&&) = default;
	
	      template<typename _Alloc>
		_Hashtable_alloc(_Alloc&& __a)
		  : __ebo_node_alloc(std::forward<_Alloc>(__a))
		{ }
	
	      __node_alloc_type&
	      _M_node_allocator()
	      { return __ebo_node_alloc::_S_get(*this); }
	
	      const __node_alloc_type&
	      _M_node_allocator() const
	      { return __ebo_node_alloc::_S_cget(*this); }
	
	      template<typename... _Args>
		__node_type*
		_M_allocate_node(_Args&&... __args);
	
	      void
	      _M_deallocate_node(__node_type* __n);
	
	      void
	      _M_deallocate_node_ptr(__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(std::size_t __n);
	
	      void
	      _M_deallocate_buckets(__bucket_type*, std::size_t __n);
	    };
	
	  // Definitions of class template _Hashtable_alloc's out-of-line member
	  // functions.
	  template<typename _NodeAlloc>
	    template<typename... _Args>
	      typename _Hashtable_alloc<_NodeAlloc>::__node_type*
	      _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
	      {

		auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);

		__node_type* __n = std::__to_address(__nptr);
		__try
		  {

		    ::new ((void*)__n) __node_type;

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

		    return __n;
		  }
		__catch(...)
		  {
		    __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
		    __throw_exception_again;
		  }
	      }
	
	  template<typename _NodeAlloc>
	    void

	    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
	    {
	      __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
	      _M_deallocate_node_ptr(__n);
	    }
	
	  template<typename _NodeAlloc>
	    void
	    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_type* __n)
	    {
	      typedef typename __node_alloc_traits::pointer _Ptr;
	      auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
	      __n->~__node_type();
	      __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
	    }
	
	  template<typename _NodeAlloc>
	    void
	    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type* __n)
	    {
	      while (__n)
		{
		  __node_type* __tmp = __n;
		  __n = __n->_M_next();
		  _M_deallocate_node(__tmp);
		}
	    }
	
	  template<typename _NodeAlloc>
	    typename _Hashtable_alloc<_NodeAlloc>::__bucket_type*
	    _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n)
	    {
	      __bucket_alloc_type __alloc(_M_node_allocator());
	
	      auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
	      __bucket_type* __p = std::__to_address(__ptr);
	      __builtin_memset(__p, 0, __n * sizeof(__bucket_type));
	      return __p;
	    }
	
	  template<typename _NodeAlloc>
	    void
	    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts,
								std::size_t __n)
	    {
	      typedef typename __bucket_alloc_traits::pointer _Ptr;
	      auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
	      __bucket_alloc_type __alloc(_M_node_allocator());
	      __bucket_alloc_traits::deallocate(__alloc, __ptr, __n);
	    }
	
	 //@} hashtable-detail
	} // namespace __detail
	_GLIBCXX_END_NAMESPACE_VERSION
	} // namespace std
	
	#endif // _HASHTABLE_POLICY_H