hashtable_policy.h source code [include/c++/7/bits/hashtable

1	// Internal policy header for unordered_set and unordered_map -- C++ --
2
3	// Copyright (C) 2010-2017 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/** @file bits/hashtable_policy.h
26	* This is an internal header file, included by other library headers.
27	* Do not attempt to use it directly.
28	* @headername{unordered_map,unordered_set}
29	*/
30
31	#ifndef _HASHTABLE_POLICY_H
32	#define _HASHTABLE_POLICY_H 1
33
34	#include <bits/stl_algobase.h> // for std::min.
35
36	namespace std _GLIBCXX_VISIBILITY(default)
37	{
38	_GLIBCXX_BEGIN_NAMESPACE_VERSION
39
40	template<typename _Key, typename _Value, typename _Alloc,
41	typename _ExtractKey, typename _Equal,
42	typename _H1, typename _H2, typename _Hash,
43	typename _RehashPolicy, typename _Traits>
44	class _Hashtable;
45
46	_GLIBCXX_END_NAMESPACE_VERSION
47
48	namespace __detail
49	{
50	_GLIBCXX_BEGIN_NAMESPACE_VERSION
51
52	/**
53	* @defgroup hashtable-detail Base and Implementation Classes
54	* @ingroup unordered_associative_containers
55	* @{
56	*/
57	template<typename _Key, typename _Value,
58	typename _ExtractKey, typename _Equal,
59	typename _H1, typename _H2, typename _Hash, typename _Traits>
60	struct _Hashtable_base;
61
62	// Helper function: return distance(first, last) for forward
63	// iterators, or 0 for input iterators.
64	template<class _Iterator>
65	inline typename std::iterator_traits<_Iterator>::difference_type
66	__distance_fw(_Iterator __first, _Iterator __last,
67	std::input_iterator_tag)
68	{ return 0; }
69
70	template<class _Iterator>
71	inline typename std::iterator_traits<_Iterator>::difference_type
72	__distance_fw(_Iterator __first, _Iterator __last,
73	std::forward_iterator_tag)
74	{ return std::distance(__first, __last); }
75
76	template<class _Iterator>
77	inline typename std::iterator_traits<_Iterator>::difference_type
78	__distance_fw(_Iterator __first, _Iterator __last)
79	{
80	typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag;
81	return __distance_fw(__first, __last, _Tag());
82	}
83
84	// Helper type used to detect whether the hash functor is noexcept.
85	template <typename _Key, typename _Hash>
86	struct __is_noexcept_hash : std::__bool_constant<
87	noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
88	{ };
89
90	struct _Identity
91	{
92	template<typename _Tp>
93	_Tp&&
94	operator()(_Tp&& __x) const
95	{ return std::forward<_Tp>(__x); }
96	};
97
98	struct _Select1st
99	{
100	template<typename _Tp>
101	auto
102	operator()(_Tp&& __x) const
103	-> decltype(std::get<0>(std::forward<_Tp>(__x)))
104	{ return std::get<0>(std::forward<_Tp>(__x)); }
105	};
106
107	template<typename _NodeAlloc>
108	struct _Hashtable_alloc;
109
110	// Functor recycling a pool of nodes and using allocation once the pool is
111	// empty.
112	template<typename _NodeAlloc>
113	struct _ReuseOrAllocNode
114	{
115	private:
116	using __node_alloc_type = _NodeAlloc;
117	using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
118	using __value_alloc_type = typename __hashtable_alloc::__value_alloc_type;
119	using __value_alloc_traits =
120	typename __hashtable_alloc::__value_alloc_traits;
121	using __node_alloc_traits =
122	typename __hashtable_alloc::__node_alloc_traits;
123	using __node_type = typename __hashtable_alloc::__node_type;
124
125	public:
126	_ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
127	: _M_nodes(__nodes), _M_h(__h) { }
128	_ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
129
130	~_ReuseOrAllocNode()
131	{ _M_h._M_deallocate_nodes(_M_nodes); }
132
133	template<typename _Arg>
134	__node_type*
135	operator()(_Arg&& __arg) const
136	{
137	if (_M_nodes)
138	{
139	__node_type* __node = _M_nodes;
140	_M_nodes = _M_nodes->_M_next();
141	__node->_M_nxt = nullptr;
142	__value_alloc_type __a(_M_h._M_node_allocator());
143	__value_alloc_traits::destroy(__a, __node->_M_valptr());
144	__try
145	{
146	__value_alloc_traits::construct(__a, __node->_M_valptr(),
147	std::forward<_Arg>(__arg));
148	}
149	__catch(...)
150	{
151	__node->~__node_type();
152	__node_alloc_traits::deallocate(_M_h._M_node_allocator(),
153	__node, 1);
154	__throw_exception_again;
155	}
156	return __node;
157	}
158	return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
159	}
160
161	private:
162	mutable __node_type* _M_nodes;
163	__hashtable_alloc& _M_h;
164	};
165
166	// Functor similar to the previous one but without any pool of nodes to
167	// recycle.
168	template<typename _NodeAlloc>
169	struct _AllocNode
170	{
171	private:
172	using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
173	using __node_type = typename __hashtable_alloc::__node_type;
174
175	public:
176	_AllocNode(__hashtable_alloc& __h)
177	: _M_h(__h) { }
178
179	template<typename _Arg>
180	__node_type*
181	operator()(_Arg&& __arg) const
182	{ return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
183
184	private:
185	__hashtable_alloc& _M_h;
186	};
187
188	// Auxiliary types used for all instantiations of _Hashtable nodes
189	// and iterators.
190
191	/**
192	* struct _Hashtable_traits
193	*
194	* Important traits for hash tables.
195	*
196	* @tparam _Cache_hash_code Boolean value. True if the value of
197	* the hash function is stored along with the value. This is a
198	* time-space tradeoff. Storing it may improve lookup speed by
199	* reducing the number of times we need to call the _Equal
200	* function.
201	*
202	* @tparam _Constant_iterators Boolean value. True if iterator and
203	* const_iterator are both constant iterator types. This is true
204	* for unordered_set and unordered_multiset, false for
205	* unordered_map and unordered_multimap.
206	*
207	* @tparam _Unique_keys Boolean value. True if the return value
208	* of _Hashtable::count(k) is always at most one, false if it may
209	* be an arbitrary number. This is true for unordered_set and
210	* unordered_map, false for unordered_multiset and
211	* unordered_multimap.
212	*/
213	template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
214	struct _Hashtable_traits
215	{
216	using __hash_cached = __bool_constant<_Cache_hash_code>;
217	using __constant_iterators = __bool_constant<_Constant_iterators>;
218	using __unique_keys = __bool_constant<_Unique_keys>;
219	};
220
221	/**
222	* struct _Hash_node_base
223	*
224	* Nodes, used to wrap elements stored in the hash table. A policy
225	* template parameter of class template _Hashtable controls whether
226	* nodes also store a hash code. In some cases (e.g. strings) this
227	* may be a performance win.
228	*/
229	struct _Hash_node_base
230	{
231	_Hash_node_base* _M_nxt;
232
233	_Hash_node_base() noexcept : _M_nxt() { }
234
235	_Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
236	};
237
238	/**
239	* struct _Hash_node_value_base
240	*
241	* Node type with the value to store.
242	*/
243	template<typename _Value>
244	struct _Hash_node_value_base : _Hash_node_base
245	{
246	typedef _Value value_type;
247
248	__gnu_cxx::__aligned_buffer<_Value> _M_storage;
249
250	_Value*
251	_M_valptr() noexcept
252	{ return _M_storage._M_ptr(); }
253
254	const _Value*
255	_M_valptr() const noexcept
256	{ return _M_storage._M_ptr(); }
257
258	_Value&
259	_M_v() noexcept
260	{ return *_M_valptr(); }
261
262	const _Value&
263	_M_v() const noexcept
264	{ return *_M_valptr(); }
265	};
266
267	/**
268	* Primary template struct _Hash_node.
269	*/
270	template<typename _Value, bool _Cache_hash_code>
271	struct _Hash_node;
272
273	/**
274	* Specialization for nodes with caches, struct _Hash_node.
275	*
276	* Base class is __detail::_Hash_node_value_base.
277	*/
278	template<typename _Value>
279	struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value>
280	{
281	std::size_t _M_hash_code;
282
283	_Hash_node*
284	_M_next() const noexcept
285	{ return static_cast<_Hash_node*>(this->_M_nxt); }
286	};
287
288	/**
289	* Specialization for nodes without caches, struct _Hash_node.
290	*
291	* Base class is __detail::_Hash_node_value_base.
292	*/
293	template<typename _Value>
294	struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value>
295	{
296	_Hash_node*
297	_M_next() const noexcept
298	{ return static_cast<_Hash_node*>(this->_M_nxt); }
299	};
300
301	/// Base class for node iterators.
302	template<typename _Value, bool _Cache_hash_code>
303	struct _Node_iterator_base
304	{
305	using __node_type = _Hash_node<_Value, _Cache_hash_code>;
306
307	__node_type* _M_cur;
308
309	_Node_iterator_base(__node_type* __p) noexcept
310	: _M_cur(__p) { }
311
312	void
313	_M_incr() noexcept
314	{ _M_cur = _M_cur->_M_next(); }
315	};
316
317	template<typename _Value, bool _Cache_hash_code>
318	inline bool
319	operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
320	const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
321	noexcept
322	{ return __x._M_cur == __y._M_cur; }
323
324	template<typename _Value, bool _Cache_hash_code>
325	inline bool
326	operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
327	const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
328	noexcept
329	{ return __x._M_cur != __y._M_cur; }
330
331	/// Node iterators, used to iterate through all the hashtable.
332	template<typename _Value, bool __constant_iterators, bool __cache>
333	struct _Node_iterator
334	: public _Node_iterator_base<_Value, __cache>
335	{
336	private:
337	using __base_type = _Node_iterator_base<_Value, __cache>;
338	using __node_type = typename __base_type::__node_type;
339
340	public:
341	typedef _Value value_type;
342	typedef std::ptrdiff_t difference_type;
343	typedef std::forward_iterator_tag iterator_category;
344
345	using pointer = typename std::conditional<__constant_iterators,
346	const _Value, _Value>::type;
347
348	using reference = typename std::conditional<__constant_iterators,
349	const _Value&, _Value&>::type;
350
351	_Node_iterator() noexcept
352	: __base_type(0) { }
353
354	explicit
355	_Node_iterator(__node_type* __p) noexcept
356	: __base_type(__p) { }
357
358	reference
359	operator*() const noexcept
360	{ return this->_M_cur->_M_v(); }
361
362	pointer
363	operator->() const noexcept
364	{ return this->_M_cur->_M_valptr(); }
365
366	_Node_iterator&
367	operator++() noexcept
368	{
369	this->_M_incr();
370	return *this;
371	}
372
373	_Node_iterator
374	operator++(int) noexcept
375	{
376	_Node_iterator __tmp(*this);
377	this->_M_incr();
378	return __tmp;
379	}
380	};
381
382	/// Node const_iterators, used to iterate through all the hashtable.
383	template<typename _Value, bool __constant_iterators, bool __cache>
384	struct _Node_const_iterator
385	: public _Node_iterator_base<_Value, __cache>
386	{
387	private:
388	using __base_type = _Node_iterator_base<_Value, __cache>;
389	using __node_type = typename __base_type::__node_type;
390
391	public:
392	typedef _Value value_type;
393	typedef std::ptrdiff_t difference_type;
394	typedef std::forward_iterator_tag iterator_category;
395
396	typedef const _Value* pointer;
397	typedef const _Value& reference;
398
399	_Node_const_iterator() noexcept
400	: __base_type(0) { }
401
402	explicit
403	_Node_const_iterator(__node_type* __p) noexcept
404	: __base_type(__p) { }
405
406	_Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
407	__cache>& __x) noexcept
408	: __base_type(__x._M_cur) { }
409
410	reference
411	operator*() const noexcept
412	{ return this->_M_cur->_M_v(); }
413
414	pointer
415	operator->() const noexcept
416	{ return this->_M_cur->_M_valptr(); }
417
418	_Node_const_iterator&
419	operator++() noexcept
420	{
421	this->_M_incr();
422	return *this;
423	}
424
425	_Node_const_iterator
426	operator++(int) noexcept
427	{
428	_Node_const_iterator __tmp(*this);
429	this->_M_incr();
430	return __tmp;
431	}
432	};
433
434	// Many of class template _Hashtable's template parameters are policy
435	// classes. These are defaults for the policies.
436
437	/// Default range hashing function: use division to fold a large number
438	/// into the range [0, N).
439	struct _Mod_range_hashing
440	{
441	typedef std::size_t first_argument_type;
442	typedef std::size_t second_argument_type;
443	typedef std::size_t result_type;
444
445	result_type
446	operator()(first_argument_type __num,
447	second_argument_type __den) const noexcept
448	{ return __num % __den; }
449	};
450
451	/// Default ranged hash function H. In principle it should be a
452	/// function object composed from objects of type H1 and H2 such that
453	/// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
454	/// h1 and h2. So instead we'll just use a tag to tell class template
455	/// hashtable to do that composition.
456	struct _Default_ranged_hash { };
457
458	/// Default value for rehash policy. Bucket size is (usually) the
459	/// smallest prime that keeps the load factor small enough.
460	struct _Prime_rehash_policy
461	{
462	using __has_load_factor = std::true_type;
463
464	_Prime_rehash_policy(float __z = 1.0) noexcept
465	: _M_max_load_factor(__z), _M_next_resize(0) { }
466
467	float
468	max_load_factor() const noexcept
469	{ return _M_max_load_factor; }
470
471	// Return a bucket size no smaller than n.
472	std::size_t
473	_M_next_bkt(std::size_t __n) const;
474
475	// Return a bucket count appropriate for n elements
476	std::size_t
477	_M_bkt_for_elements(std::size_t __n) const
478	{ return __builtin_ceil(__n / (long double)_M_max_load_factor); }
479
480	// __n_bkt is current bucket count, __n_elt is current element count,
481	// and __n_ins is number of elements to be inserted. Do we need to
482	// increase bucket count? If so, return make_pair(true, n), where n
483	// is the new bucket count. If not, return make_pair(false, 0).
484	std::pair<bool, std::size_t>
485	_M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
486	std::size_t __n_ins) const;
487
488	typedef std::size_t _State;
489
490	_State
491	_M_state() const
492	{ return _M_next_resize; }
493
494	void
495	_M_reset() noexcept
496	{ _M_next_resize = 0; }
497
498	void
499	_M_reset(_State __state)
500	{ _M_next_resize = __state; }
501
502	static const std::size_t _S_growth_factor = 2;
503
504	float _M_max_load_factor;
505	mutable std::size_t _M_next_resize;
506	};
507
508	/// Range hashing function assuming that second arg is a power of 2.
509	struct _Mask_range_hashing
510	{
511	typedef std::size_t first_argument_type;
512	typedef std::size_t second_argument_type;
513	typedef std::size_t result_type;
514
515	result_type
516	operator()(first_argument_type __num,
517	second_argument_type __den) const noexcept
518	{ return __num & (__den - 1); }
519	};
520
521	/// Compute closest power of 2.
522	_GLIBCXX14_CONSTEXPR
523	inline std::size_t
524	__clp2(std::size_t __n) noexcept
525	{
526	#if __SIZEOF_SIZE_T__ >= 8
527	std::uint_fast64_t __x = __n;
528	#else
529	std::uint_fast32_t __x = __n;
530	#endif
531	// Algorithm from Hacker's Delight, Figure 3-3.
532	__x = __x - 1;
533	__x = __x \| (__x >> 1);
534	__x = __x \| (__x >> 2);
535	__x = __x \| (__x >> 4);
536	__x = __x \| (__x >> 8);
537	__x = __x \| (__x >>16);
538	#if __SIZEOF_SIZE_T__ >= 8
539	__x = __x \| (__x >>32);
540	#endif
541	return __x + 1;
542	}
543
544	/// Rehash policy providing power of 2 bucket numbers. Avoids modulo
545	/// operations.
546	struct _Power2_rehash_policy
547	{
548	using __has_load_factor = std::true_type;
549
550	_Power2_rehash_policy(float __z = 1.0) noexcept
551	: _M_max_load_factor(__z), _M_next_resize(0) { }
552
553	float
554	max_load_factor() const noexcept
555	{ return _M_max_load_factor; }
556
557	// Return a bucket size no smaller than n (as long as n is not above the
558	// highest power of 2).
559	std::size_t
560	_M_next_bkt(std::size_t __n) noexcept
561	{
562	const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
563	const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
564	std::size_t __res = __clp2(__n);
565
566	if (__res == __n)
567	__res <<= 1;
568
569	if (__res == 0)
570	__res = __max_bkt;
571
572	if (__res == __max_bkt)
573	// Set next resize to the max value so that we never try to rehash again
574	// as we already reach the biggest possible bucket number.
575	// Note that it might result in max_load_factor not being respected.
576	_M_next_resize = std::size_t(-1);
577	else
578	_M_next_resize
579	= __builtin_ceil(__res * (long double)_M_max_load_factor);
580
581	return __res;
582	}
583
584	// Return a bucket count appropriate for n elements
585	std::size_t
586	_M_bkt_for_elements(std::size_t __n) const noexcept
587	{ return __builtin_ceil(__n / (long double)_M_max_load_factor); }
588
589	// __n_bkt is current bucket count, __n_elt is current element count,
590	// and __n_ins is number of elements to be inserted. Do we need to
591	// increase bucket count? If so, return make_pair(true, n), where n
592	// is the new bucket count. If not, return make_pair(false, 0).
593	std::pair<bool, std::size_t>
594	_M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
595	std::size_t __n_ins) noexcept
596	{
597	if (__n_elt + __n_ins >= _M_next_resize)
598	{
599	long double __min_bkts = (__n_elt + __n_ins)
600	/ (long double)_M_max_load_factor;
601	if (__min_bkts >= __n_bkt)
602	return std::make_pair(true,
603	_M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
604	__n_bkt * _S_growth_factor)));
605
606	_M_next_resize
607	= __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
608	return std::make_pair(false, 0);
609	}
610	else
611	return std::make_pair(false, 0);
612	}
613
614	typedef std::size_t _State;
615
616	_State
617	_M_state() const noexcept
618	{ return _M_next_resize; }
619
620	void
621	_M_reset() noexcept
622	{ _M_next_resize = 0; }
623
624	void
625	_M_reset(_State __state) noexcept
626	{ _M_next_resize = __state; }
627
628	static const std::size_t _S_growth_factor = 2;
629
630	float _M_max_load_factor;
631	std::size_t _M_next_resize;
632	};
633
634	// Base classes for std::_Hashtable. We define these base classes
635	// because in some cases we want to do different things depending on
636	// the value of a policy class. In some cases the policy class
637	// affects which member functions and nested typedefs are defined;
638	// we handle that by specializing base class templates. Several of
639	// the base class templates need to access other members of class
640	// template _Hashtable, so we use a variant of the "Curiously
641	// Recurring Template Pattern" (CRTP) technique.
642
643	/**
644	* Primary class template _Map_base.
645	*
646	* If the hashtable has a value type of the form pair<T1, T2> and a
647	* key extraction policy (_ExtractKey) that returns the first part
648	* of the pair, the hashtable gets a mapped_type typedef. If it
649	* satisfies those criteria and also has unique keys, then it also
650	* gets an operator[].
651	*/
652	template<typename _Key, typename _Value, typename _Alloc,
653	typename _ExtractKey, typename _Equal,
654	typename _H1, typename _H2, typename _Hash,
655	typename _RehashPolicy, typename _Traits,
656	bool _Unique_keys = _Traits::__unique_keys::value>
657	struct _Map_base { };
658
659	/// Partial specialization, __unique_keys set to false.
660	template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
661	typename _H1, typename _H2, typename _Hash,
662	typename _RehashPolicy, typename _Traits>
663	struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
664	_H1, _H2, _Hash, _RehashPolicy, _Traits, false>
665	{
666	using mapped_type = typename std::tuple_element<1, _Pair>::type;
667	};
668
669	/// Partial specialization, __unique_keys set to true.
670	template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
671	typename _H1, typename _H2, typename _Hash,
672	typename _RehashPolicy, typename _Traits>
673	struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
674	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>
675	{
676	private:
677	using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
678	_Select1st,
679	_Equal, _H1, _H2, _Hash,
680	_Traits>;
681
682	using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
683	_Select1st, _Equal,
684	_H1, _H2, _Hash, _RehashPolicy, _Traits>;
685
686	using __hash_code = typename __hashtable_base::__hash_code;
687	using __node_type = typename __hashtable_base::__node_type;
688
689	public:
690	using key_type = typename __hashtable_base::key_type;
691	using iterator = typename __hashtable_base::iterator;
692	using mapped_type = typename std::tuple_element<1, _Pair>::type;
693
694	mapped_type&
695	operator[](const key_type& __k);
696
697	mapped_type&
698	operator[](key_type&& __k);
699
700	// _GLIBCXX_RESOLVE_LIB_DEFECTS
701	// DR 761. unordered_map needs an at() member function.
702	mapped_type&
703	at(const key_type& __k);
704
705	const mapped_type&
706	at(const key_type& __k) const;
707	};
708
709	template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
710	typename _H1, typename _H2, typename _Hash,
711	typename _RehashPolicy, typename _Traits>
712	auto
713	_Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
714	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
715	operator[](const key_type& __k)
716	-> mapped_type&
717	{
718	__hashtable* __h = static_cast<__hashtable*>(this);
719	__hash_code __code = __h->_M_hash_code(__k);
720	std::size_t __n = __h->_M_bucket_index(__k, __code);
721	__node_type* __p = __h->_M_find_node(__n, __k, __code);
722
723	if (!__p)
724	{
725	__p = __h->_M_allocate_node(std::piecewise_construct,
726	std::tuple<const key_type&>(__k),
727	std::tuple<>());
728	return __h->_M_insert_unique_node(__n, __code, __p)->second;
729	}
730
731	return __p->_M_v().second;
732	}
733
734	template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
735	typename _H1, typename _H2, typename _Hash,
736	typename _RehashPolicy, typename _Traits>
737	auto
738	_Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
739	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
740	operator[](key_type&& __k)
741	-> mapped_type&
742	{
743	__hashtable* __h = static_cast<__hashtable*>(this);
744	__hash_code __code = __h->_M_hash_code(__k);
745	std::size_t __n = __h->_M_bucket_index(__k, __code);
746	__node_type* __p = __h->_M_find_node(__n, __k, __code);
747
748	if (!__p)
749	{
750	__p = __h->_M_allocate_node(std::piecewise_construct,
751	std::forward_as_tuple(std::move(__k)),
752	std::tuple<>());
753	return __h->_M_insert_unique_node(__n, __code, __p)->second;
754	}
755
756	return __p->_M_v().second;
757	}
758
759	template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
760	typename _H1, typename _H2, typename _Hash,
761	typename _RehashPolicy, typename _Traits>
762	auto
763	_Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
764	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
765	at(const key_type& __k)
766	-> mapped_type&
767	{
768	__hashtable* __h = static_cast<__hashtable*>(this);
769	__hash_code __code = __h->_M_hash_code(__k);
770	std::size_t __n = __h->_M_bucket_index(__k, __code);
771	__node_type* __p = __h->_M_find_node(__n, __k, __code);
772
773	if (!__p)
774	__throw_out_of_range(__N("_Map_base::at"));
775	return __p->_M_v().second;
776	}
777
778	template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
779	typename _H1, typename _H2, typename _Hash,
780	typename _RehashPolicy, typename _Traits>
781	auto
782	_Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
783	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
784	at(const key_type& __k) const
785	-> const mapped_type&
786	{
787	const __hashtable* __h = static_cast<const __hashtable*>(this);
788	__hash_code __code = __h->_M_hash_code(__k);
789	std::size_t __n = __h->_M_bucket_index(__k, __code);
790	__node_type* __p = __h->_M_find_node(__n, __k, __code);
791
792	if (!__p)
793	__throw_out_of_range(__N("_Map_base::at"));
794	return __p->_M_v().second;
795	}
796
797	/**
798	* Primary class template _Insert_base.
799	*
800	* Defines @c insert member functions appropriate to all _Hashtables.
801	*/
802	template<typename _Key, typename _Value, typename _Alloc,
803	typename _ExtractKey, typename _Equal,
804	typename _H1, typename _H2, typename _Hash,
805	typename _RehashPolicy, typename _Traits>
806	struct _Insert_base
807	{
808	protected:
809	using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
810	_Equal, _H1, _H2, _Hash,
811	_RehashPolicy, _Traits>;
812
813	using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
814	_Equal, _H1, _H2, _Hash,
815	_Traits>;
816
817	using value_type = typename __hashtable_base::value_type;
818	using iterator = typename __hashtable_base::iterator;
819	using const_iterator = typename __hashtable_base::const_iterator;
820	using size_type = typename __hashtable_base::size_type;
821
822	using __unique_keys = typename __hashtable_base::__unique_keys;
823	using __ireturn_type = typename __hashtable_base::__ireturn_type;
824	using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>;
825	using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
826	using __node_gen_type = _AllocNode<__node_alloc_type>;
827
828	__hashtable&
829	_M_conjure_hashtable()
830	{ return (static_cast<__hashtable>(this)); }
831
832	template<typename _InputIterator, typename _NodeGetter>
833	void
834	_M_insert_range(_InputIterator __first, _InputIterator __last,
835	const _NodeGetter&);
836
837	public:
838	__ireturn_type
839	insert(const value_type& __v)
840	{
841	__hashtable& __h = _M_conjure_hashtable();
842	__node_gen_type __node_gen(__h);
843	return __h._M_insert(__v, __node_gen, __unique_keys());
844	}
845
846	iterator
847	insert(const_iterator __hint, const value_type& __v)
848	{
849	__hashtable& __h = _M_conjure_hashtable();
850	__node_gen_type __node_gen(__h);
851	return __h._M_insert(__hint, __v, __node_gen, __unique_keys());
852	}
853
854	void
855	insert(initializer_list<value_type> __l)
856	{ this->insert(__l.begin(), __l.end()); }
857
858	template<typename _InputIterator>
859	void
860	insert(_InputIterator __first, _InputIterator __last)
861	{
862	__hashtable& __h = _M_conjure_hashtable();
863	__node_gen_type __node_gen(__h);
864	return _M_insert_range(__first, __last, __node_gen);
865	}
866	};
867
868	template<typename _Key, typename _Value, typename _Alloc,
869	typename _ExtractKey, typename _Equal,
870	typename _H1, typename _H2, typename _Hash,
871	typename _RehashPolicy, typename _Traits>
872	template<typename _InputIterator, typename _NodeGetter>
873	void
874	_Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
875	_RehashPolicy, _Traits>::
876	_M_insert_range(_InputIterator __first, _InputIterator __last,
877	const _NodeGetter& __node_gen)
878	{
879	using __rehash_type = typename __hashtable::__rehash_type;
880	using __rehash_state = typename __hashtable::__rehash_state;
881	using pair_type = std::pair<bool, std::size_t>;
882
883	size_type __n_elt = __detail::__distance_fw(__first, __last);
884
885	__hashtable& __h = _M_conjure_hashtable();
886	__rehash_type& __rehash = __h._M_rehash_policy;
887	const __rehash_state& __saved_state = __rehash._M_state();
888	pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
889	__h._M_element_count,
890	__n_elt);
891
892	if (__do_rehash.first)
893	__h._M_rehash(__do_rehash.second, __saved_state);
894
895	for (; __first != __last; ++__first)
896	__h._M_insert(*__first, __node_gen, __unique_keys());
897	}
898
899	/**
900	* Primary class template _Insert.
901	*
902	* Defines @c insert member functions that depend on _Hashtable policies,
903	* via partial specializations.
904	*/
905	template<typename _Key, typename _Value, typename _Alloc,
906	typename _ExtractKey, typename _Equal,
907	typename _H1, typename _H2, typename _Hash,
908	typename _RehashPolicy, typename _Traits,
909	bool _Constant_iterators = _Traits::__constant_iterators::value>
910	struct _Insert;
911
912	/// Specialization.
913	template<typename _Key, typename _Value, typename _Alloc,
914	typename _ExtractKey, typename _Equal,
915	typename _H1, typename _H2, typename _Hash,
916	typename _RehashPolicy, typename _Traits>
917	struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
918	_RehashPolicy, _Traits, true>
919	: public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
920	_H1, _H2, _Hash, _RehashPolicy, _Traits>
921	{
922	using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
923	_Equal, _H1, _H2, _Hash,
924	_RehashPolicy, _Traits>;
925
926	using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
927	_Equal, _H1, _H2, _Hash,
928	_Traits>;
929
930	using value_type = typename __base_type::value_type;
931	using iterator = typename __base_type::iterator;
932	using const_iterator = typename __base_type::const_iterator;
933
934	using __unique_keys = typename __base_type::__unique_keys;
935	using __ireturn_type = typename __hashtable_base::__ireturn_type;
936	using __hashtable = typename __base_type::__hashtable;
937	using __node_gen_type = typename __base_type::__node_gen_type;
938
939	using __base_type::insert;
940
941	__ireturn_type
942	insert(value_type&& __v)
943	{
944	__hashtable& __h = this->_M_conjure_hashtable();
945	__node_gen_type __node_gen(__h);
946	return __h._M_insert(std::move(__v), __node_gen, __unique_keys());
947	}
948
949	iterator
950	insert(const_iterator __hint, value_type&& __v)
951	{
952	__hashtable& __h = this->_M_conjure_hashtable();
953	__node_gen_type __node_gen(__h);
954	return __h._M_insert(__hint, std::move(__v), __node_gen,
955	__unique_keys());
956	}
957	};
958
959	/// Specialization.
960	template<typename _Key, typename _Value, typename _Alloc,
961	typename _ExtractKey, typename _Equal,
962	typename _H1, typename _H2, typename _Hash,
963	typename _RehashPolicy, typename _Traits>
964	struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
965	_RehashPolicy, _Traits, false>
966	: public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
967	_H1, _H2, _Hash, _RehashPolicy, _Traits>
968	{
969	using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
970	_Equal, _H1, _H2, _Hash,
971	_RehashPolicy, _Traits>;
972	using value_type = typename __base_type::value_type;
973	using iterator = typename __base_type::iterator;
974	using const_iterator = typename __base_type::const_iterator;
975
976	using __unique_keys = typename __base_type::__unique_keys;
977	using __hashtable = typename __base_type::__hashtable;
978	using __ireturn_type = typename __base_type::__ireturn_type;
979
980	using __base_type::insert;
981
982	template<typename _Pair>
983	using __is_cons = std::is_constructible<value_type, _Pair&&>;
984
985	template<typename _Pair>
986	using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
987
988	template<typename _Pair>
989	using _IFconsp = typename _IFcons<_Pair>::type;
990
991	template<typename _Pair, typename = _IFconsp<_Pair>>
992	__ireturn_type
993	insert(_Pair&& __v)
994	{
995	__hashtable& __h = this->_M_conjure_hashtable();
996	return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
997	}
998
999	template<typename _Pair, typename = _IFconsp<_Pair>>
1000	iterator
1001	insert(const_iterator __hint, _Pair&& __v)
1002	{
1003	__hashtable& __h = this->_M_conjure_hashtable();
1004	return __h._M_emplace(__hint, __unique_keys(),
1005	std::forward<_Pair>(__v));
1006	}
1007	};
1008
1009	template<typename _Policy>
1010	using __has_load_factor = typename _Policy::__has_load_factor;
1011
1012	/**
1013	* Primary class template _Rehash_base.
1014	*
1015	* Give hashtable the max_load_factor functions and reserve iff the
1016	* rehash policy supports it.
1017	*/
1018	template<typename _Key, typename _Value, typename _Alloc,
1019	typename _ExtractKey, typename _Equal,
1020	typename _H1, typename _H2, typename _Hash,
1021	typename _RehashPolicy, typename _Traits,
1022	typename =
1023	__detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>>
1024	struct _Rehash_base;
1025
1026	/// Specialization when rehash policy doesn't provide load factor management.
1027	template<typename _Key, typename _Value, typename _Alloc,
1028	typename _ExtractKey, typename _Equal,
1029	typename _H1, typename _H2, typename _Hash,
1030	typename _RehashPolicy, typename _Traits>
1031	struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1032	_H1, _H2, _Hash, _RehashPolicy, _Traits,
1033	std::false_type>
1034	{
1035	};
1036
1037	/// Specialization when rehash policy provide load factor management.
1038	template<typename _Key, typename _Value, typename _Alloc,
1039	typename _ExtractKey, typename _Equal,
1040	typename _H1, typename _H2, typename _Hash,
1041	typename _RehashPolicy, typename _Traits>
1042	struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1043	_H1, _H2, _Hash, _RehashPolicy, _Traits,
1044	std::true_type>
1045	{
1046	using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1047	_Equal, _H1, _H2, _Hash,
1048	_RehashPolicy, _Traits>;
1049
1050	float
1051	max_load_factor() const noexcept
1052	{
1053	const __hashtable* __this = static_cast<const __hashtable*>(this);
1054	return __this->__rehash_policy().max_load_factor();
1055	}
1056
1057	void
1058	max_load_factor(float __z)
1059	{
1060	__hashtable* __this = static_cast<__hashtable*>(this);
1061	__this->__rehash_policy(_RehashPolicy(__z));
1062	}
1063
1064	void
1065	reserve(std::size_t __n)
1066	{
1067	__hashtable* __this = static_cast<__hashtable*>(this);
1068	__this->rehash(__builtin_ceil(__n / max_load_factor()));
1069	}
1070	};
1071
1072	/**
1073	* Primary class template _Hashtable_ebo_helper.
1074	*
1075	* Helper class using EBO when it is not forbidden (the type is not
1076	* final) and when it is worth it (the type is empty.)
1077	*/
1078	template<int _Nm, typename _Tp,
1079	bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1080	struct _Hashtable_ebo_helper;
1081
1082	/// Specialization using EBO.
1083	template<int _Nm, typename _Tp>
1084	struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1085	: private _Tp
1086	{
1087	_Hashtable_ebo_helper() = default;
1088
1089	template<typename _OtherTp>
1090	_Hashtable_ebo_helper(_OtherTp&& __tp)
1091	: _Tp(std::forward<_OtherTp>(__tp))
1092	{ }
1093
1094	static const _Tp&
1095	_S_cget(const _Hashtable_ebo_helper& __eboh)
1096	{ return static_cast<const _Tp&>(__eboh); }
1097
1098	static _Tp&
1099	_S_get(_Hashtable_ebo_helper& __eboh)
1100	{ return static_cast<_Tp&>(__eboh); }
1101	};
1102
1103	/// Specialization not using EBO.
1104	template<int _Nm, typename _Tp>
1105	struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1106	{
1107	_Hashtable_ebo_helper() = default;
1108
1109	template<typename _OtherTp>
1110	_Hashtable_ebo_helper(_OtherTp&& __tp)
1111	: _M_tp(std::forward<_OtherTp>(__tp))
1112	{ }
1113
1114	static const _Tp&
1115	_S_cget(const _Hashtable_ebo_helper& __eboh)
1116	{ return __eboh._M_tp; }
1117
1118	static _Tp&
1119	_S_get(_Hashtable_ebo_helper& __eboh)
1120	{ return __eboh._M_tp; }
1121
1122	private:
1123	_Tp _M_tp;
1124	};
1125
1126	/**
1127	* Primary class template _Local_iterator_base.
1128	*
1129	* Base class for local iterators, used to iterate within a bucket
1130	* but not between buckets.
1131	*/
1132	template<typename _Key, typename _Value, typename _ExtractKey,
1133	typename _H1, typename _H2, typename _Hash,
1134	bool __cache_hash_code>
1135	struct _Local_iterator_base;
1136
1137	/**
1138	* Primary class template _Hash_code_base.
1139	*
1140	* Encapsulates two policy issues that aren't quite orthogonal.
1141	* (1) the difference between using a ranged hash function and using
1142	* the combination of a hash function and a range-hashing function.
1143	* In the former case we don't have such things as hash codes, so
1144	* we have a dummy type as placeholder.
1145	* (2) Whether or not we cache hash codes. Caching hash codes is
1146	* meaningless if we have a ranged hash function.
1147	*
1148	* We also put the key extraction objects here, for convenience.
1149	* Each specialization derives from one or more of the template
1150	* parameters to benefit from Ebo. This is important as this type
1151	* is inherited in some cases by the _Local_iterator_base type used
1152	* to implement local_iterator and const_local_iterator. As with
1153	* any iterator type we prefer to make it as small as possible.
1154	*
1155	* Primary template is unused except as a hook for specializations.
1156	*/
1157	template<typename _Key, typename _Value, typename _ExtractKey,
1158	typename _H1, typename _H2, typename _Hash,
1159	bool __cache_hash_code>
1160	struct _Hash_code_base;
1161
1162	/// Specialization: ranged hash function, no caching hash codes. H1
1163	/// and H2 are provided but ignored. We define a dummy hash code type.
1164	template<typename _Key, typename _Value, typename _ExtractKey,
1165	typename _H1, typename _H2, typename _Hash>
1166	struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
1167	: private _Hashtable_ebo_helper<0, _ExtractKey>,
1168	private _Hashtable_ebo_helper<1, _Hash>
1169	{
1170	private:
1171	using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
1172	using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
1173
1174	protected:
1175	typedef void* __hash_code;
1176	typedef _Hash_node<_Value, false> __node_type;
1177
1178	// We need the default constructor for the local iterators and _Hashtable
1179	// default constructor.
1180	_Hash_code_base() = default;
1181
1182	_Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
1183	const _Hash& __h)
1184	: __ebo_extract_key(__ex), __ebo_hash(__h) { }
1185
1186	__hash_code
1187	_M_hash_code(const _Key& __key) const
1188	{ return 0; }
1189
1190	std::size_t
1191	_M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
1192	{ return _M_ranged_hash()(__k, __n); }
1193
1194	std::size_t
1195	_M_bucket_index(const __node_type* __p, std::size_t __n) const
1196	noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(),
1197	(std::size_t)0)) )
1198	{ return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); }
1199
1200	void
1201	_M_store_code(__node_type*, __hash_code) const
1202	{ }
1203
1204	void
1205	_M_copy_code(__node_type, const __node_type) const
1206	{ }
1207
1208	void
1209	_M_swap(_Hash_code_base& __x)
1210	{
1211	std::swap(_M_extract(), __x._M_extract());
1212	std::swap(_M_ranged_hash(), __x._M_ranged_hash());
1213	}
1214
1215	const _ExtractKey&
1216	_M_extract() const { return __ebo_extract_key::_S_cget(*this); }
1217
1218	_ExtractKey&
1219	_M_extract() { return __ebo_extract_key::_S_get(*this); }
1220
1221	const _Hash&
1222	_M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }
1223
1224	_Hash&
1225	_M_ranged_hash() { return __ebo_hash::_S_get(*this); }
1226	};
1227
1228	// No specialization for ranged hash function while caching hash codes.
1229	// That combination is meaningless, and trying to do it is an error.
1230
1231	/// Specialization: ranged hash function, cache hash codes. This
1232	/// combination is meaningless, so we provide only a declaration
1233	/// and no definition.
1234	template<typename _Key, typename _Value, typename _ExtractKey,
1235	typename _H1, typename _H2, typename _Hash>
1236	struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
1237
1238	/// Specialization: hash function and range-hashing function, no
1239	/// caching of hash codes.
1240	/// Provides typedef and accessor required by C++ 11.
1241	template<typename _Key, typename _Value, typename _ExtractKey,
1242	typename _H1, typename _H2>
1243	struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
1244	_Default_ranged_hash, false>
1245	: private _Hashtable_ebo_helper<0, _ExtractKey>,
1246	private _Hashtable_ebo_helper<1, _H1>,
1247	private _Hashtable_ebo_helper<2, _H2>
1248	{
1249	private:
1250	using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
1251	using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
1252	using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
1253
1254	// Gives the local iterator implementation access to _M_bucket_index().
1255	friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
1256	_Default_ranged_hash, false>;
1257
1258	public:
1259	typedef _H1 hasher;
1260
1261	hasher
1262	hash_function() const
1263	{ return _M_h1(); }
1264
1265	protected:
1266	typedef std::size_t __hash_code;
1267	typedef _Hash_node<_Value, false> __node_type;
1268
1269	// We need the default constructor for the local iterators and _Hashtable
1270	// default constructor.
1271	_Hash_code_base() = default;
1272
1273	_Hash_code_base(const _ExtractKey& __ex,
1274	const _H1& __h1, const _H2& __h2,
1275	const _Default_ranged_hash&)
1276	: __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
1277
1278	__hash_code
1279	_M_hash_code(const _Key& __k) const
1280	{ return _M_h1()(__k); }
1281
1282	std::size_t
1283	_M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
1284	{ return _M_h2()(__c, __n); }
1285
1286	std::size_t
1287	_M_bucket_index(const __node_type* __p, std::size_t __n) const
1288	noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>()))
1289	&& noexcept(declval<const _H2&>()((__hash_code)0,
1290	(std::size_t)0)) )
1291	{ return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); }
1292
1293	void
1294	_M_store_code(__node_type*, __hash_code) const
1295	{ }
1296
1297	void
1298	_M_copy_code(__node_type, const __node_type) const
1299	{ }
1300
1301	void
1302	_M_swap(_Hash_code_base& __x)
1303	{
1304	std::swap(_M_extract(), __x._M_extract());
1305	std::swap(_M_h1(), __x._M_h1());
1306	std::swap(_M_h2(), __x._M_h2());
1307	}
1308
1309	const _ExtractKey&
1310	_M_extract() const { return __ebo_extract_key::_S_cget(*this); }
1311
1312	_ExtractKey&
1313	_M_extract() { return __ebo_extract_key::_S_get(*this); }
1314
1315	const _H1&
1316	_M_h1() const { return __ebo_h1::_S_cget(*this); }
1317
1318	_H1&
1319	_M_h1() { return __ebo_h1::_S_get(*this); }
1320
1321	const _H2&
1322	_M_h2() const { return __ebo_h2::_S_cget(*this); }
1323
1324	_H2&
1325	_M_h2() { return __ebo_h2::_S_get(*this); }
1326	};
1327
1328	/// Specialization: hash function and range-hashing function,
1329	/// caching hash codes. H is provided but ignored. Provides
1330	/// typedef and accessor required by C++ 11.
1331	template<typename _Key, typename _Value, typename _ExtractKey,
1332	typename _H1, typename _H2>
1333	struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
1334	_Default_ranged_hash, true>
1335	: private _Hashtable_ebo_helper<0, _ExtractKey>,
1336	private _Hashtable_ebo_helper<1, _H1>,
1337	private _Hashtable_ebo_helper<2, _H2>
1338	{
1339	private:
1340	// Gives the local iterator implementation access to _M_h2().
1341	friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
1342	_Default_ranged_hash, true>;
1343
1344	using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
1345	using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
1346	using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
1347
1348	public:
1349	typedef _H1 hasher;
1350
1351	hasher
1352	hash_function() const
1353	{ return _M_h1(); }
1354
1355	protected:
1356	typedef std::size_t __hash_code;
1357	typedef _Hash_node<_Value, true> __node_type;
1358
1359	// We need the default constructor for _Hashtable default constructor.
1360	_Hash_code_base() = default;
1361	_Hash_code_base(const _ExtractKey& __ex,
1362	const _H1& __h1, const _H2& __h2,
1363	const _Default_ranged_hash&)
1364	: __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
1365
1366	__hash_code
1367	_M_hash_code(const _Key& __k) const
1368	{ return _M_h1()(__k); }
1369
1370	std::size_t
1371	_M_bucket_index(const _Key&, __hash_code __c,
1372	std::size_t __n) const
1373	{ return _M_h2()(__c, __n); }
1374
1375	std::size_t
1376	_M_bucket_index(const __node_type* __p, std::size_t __n) const
1377	noexcept( noexcept(declval<const _H2&>()((__hash_code)0,
1378	(std::size_t)0)) )
1379	{ return _M_h2()(__p->_M_hash_code, __n); }
1380
1381	void
1382	_M_store_code(__node_type* __n, __hash_code __c) const
1383	{ __n->_M_hash_code = __c; }
1384
1385	void
1386	_M_copy_code(__node_type* __to, const __node_type* __from) const
1387	{ __to->_M_hash_code = __from->_M_hash_code; }
1388
1389	void
1390	_M_swap(_Hash_code_base& __x)
1391	{
1392	std::swap(_M_extract(), __x._M_extract());
1393	std::swap(_M_h1(), __x._M_h1());
1394	std::swap(_M_h2(), __x._M_h2());
1395	}
1396
1397	const _ExtractKey&
1398	_M_extract() const { return __ebo_extract_key::_S_cget(*this); }
1399
1400	_ExtractKey&
1401	_M_extract() { return __ebo_extract_key::_S_get(*this); }
1402
1403	const _H1&
1404	_M_h1() const { return __ebo_h1::_S_cget(*this); }
1405
1406	_H1&
1407	_M_h1() { return __ebo_h1::_S_get(*this); }
1408
1409	const _H2&
1410	_M_h2() const { return __ebo_h2::_S_cget(*this); }
1411
1412	_H2&
1413	_M_h2() { return __ebo_h2::_S_get(*this); }
1414	};
1415
1416	/**
1417	* Primary class template _Equal_helper.
1418	*
1419	*/
1420	template <typename _Key, typename _Value, typename _ExtractKey,
1421	typename _Equal, typename _HashCodeType,
1422	bool __cache_hash_code>
1423	struct _Equal_helper;
1424
1425	/// Specialization.
1426	template<typename _Key, typename _Value, typename _ExtractKey,
1427	typename _Equal, typename _HashCodeType>
1428	struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
1429	{
1430	static bool
1431	_S_equals(const _Equal& __eq, const _ExtractKey& __extract,
1432	const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
1433	{ return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); }
1434	};
1435
1436	/// Specialization.
1437	template<typename _Key, typename _Value, typename _ExtractKey,
1438	typename _Equal, typename _HashCodeType>
1439	struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
1440	{
1441	static bool
1442	_S_equals(const _Equal& __eq, const _ExtractKey& __extract,
1443	const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
1444	{ return __eq(__k, __extract(__n->_M_v())); }
1445	};
1446
1447
1448	/// Partial specialization used when nodes contain a cached hash code.
1449	template<typename _Key, typename _Value, typename _ExtractKey,
1450	typename _H1, typename _H2, typename _Hash>
1451	struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1452	_H1, _H2, _Hash, true>
1453	: private _Hashtable_ebo_helper<0, _H2>
1454	{
1455	protected:
1456	using __base_type = _Hashtable_ebo_helper<0, _H2>;
1457	using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1458	_H1, _H2, _Hash, true>;
1459
1460	_Local_iterator_base() = default;
1461	_Local_iterator_base(const __hash_code_base& __base,
1462	_Hash_node<_Value, true>* __p,
1463	std::size_t __bkt, std::size_t __bkt_count)
1464	: __base_type(__base._M_h2()),
1465	_M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
1466
1467	void
1468	_M_incr()
1469	{
1470	_M_cur = _M_cur->_M_next();
1471	if (_M_cur)
1472	{
1473	std::size_t __bkt
1474	= __base_type::_S_get(*this)(_M_cur->_M_hash_code,
1475	_M_bucket_count);
1476	if (__bkt != _M_bucket)
1477	_M_cur = nullptr;
1478	}
1479	}
1480
1481	_Hash_node<_Value, true>* _M_cur;
1482	std::size_t _M_bucket;
1483	std::size_t _M_bucket_count;
1484
1485	public:
1486	const void*
1487	_M_curr() const { return _M_cur; } // for equality ops
1488
1489	std::size_t
1490	_M_get_bucket() const { return _M_bucket; } // for debug mode
1491	};
1492
1493	// Uninitialized storage for a _Hash_code_base.
1494	// This type is DefaultConstructible and Assignable even if the
1495	// _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1496	// can be DefaultConstructible and Assignable.
1497	template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1498	struct _Hash_code_storage
1499	{
1500	__gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1501
1502	_Tp*
1503	_M_h() { return _M_storage._M_ptr(); }
1504
1505	const _Tp*
1506	_M_h() const { return _M_storage._M_ptr(); }
1507	};
1508
1509	// Empty partial specialization for empty _Hash_code_base types.
1510	template<typename _Tp>
1511	struct _Hash_code_storage<_Tp, true>
1512	{
1513	static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1514
1515	// As _Tp is an empty type there will be no bytes written/read through
1516	// the cast pointer, so no strict-aliasing violation.
1517	_Tp*
1518	_M_h() { return reinterpret_cast<_Tp*>(this); }
1519
1520	const _Tp*
1521	_M_h() const { return reinterpret_cast<const _Tp*>(this); }
1522	};
1523
1524	template<typename _Key, typename _Value, typename _ExtractKey,
1525	typename _H1, typename _H2, typename _Hash>
1526	using __hash_code_for_local_iter
1527	= _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1528	_H1, _H2, _Hash, false>>;
1529
1530	// Partial specialization used when hash codes are not cached
1531	template<typename _Key, typename _Value, typename _ExtractKey,
1532	typename _H1, typename _H2, typename _Hash>
1533	struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1534	_H1, _H2, _Hash, false>
1535	: __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash>
1536	{
1537	protected:
1538	using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1539	_H1, _H2, _Hash, false>;
1540
1541	_Local_iterator_base() : _M_bucket_count(-1) { }
1542
1543	_Local_iterator_base(const __hash_code_base& __base,
1544	_Hash_node<_Value, false>* __p,
1545	std::size_t __bkt, std::size_t __bkt_count)
1546	: _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1547	{ _M_init(__base); }
1548
1549	~_Local_iterator_base()
1550	{
1551	if (_M_bucket_count != -1)
1552	_M_destroy();
1553	}
1554
1555	_Local_iterator_base(const _Local_iterator_base& __iter)
1556	: _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket),
1557	_M_bucket_count(__iter._M_bucket_count)
1558	{
1559	if (_M_bucket_count != -1)
1560	_M_init(*__iter._M_h());
1561	}
1562
1563	_Local_iterator_base&
1564	operator=(const _Local_iterator_base& __iter)
1565	{
1566	if (_M_bucket_count != -1)
1567	_M_destroy();
1568	_M_cur = __iter._M_cur;
1569	_M_bucket = __iter._M_bucket;
1570	_M_bucket_count = __iter._M_bucket_count;
1571	if (_M_bucket_count != -1)
1572	_M_init(*__iter._M_h());
1573	return *this;
1574	}
1575
1576	void
1577	_M_incr()
1578	{
1579	_M_cur = _M_cur->_M_next();
1580	if (_M_cur)
1581	{
1582	std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur,
1583	_M_bucket_count);
1584	if (__bkt != _M_bucket)
1585	_M_cur = nullptr;
1586	}
1587	}
1588
1589	_Hash_node<_Value, false>* _M_cur;
1590	std::size_t _M_bucket;
1591	std::size_t _M_bucket_count;
1592
1593	void
1594	_M_init(const __hash_code_base& __base)
1595	{ ::new(this->_M_h()) __hash_code_base(__base); }
1596
1597	void
1598	_M_destroy() { this->_M_h()->~__hash_code_base(); }
1599
1600	public:
1601	const void*
1602	_M_curr() const { return _M_cur; } // for equality ops and debug mode
1603
1604	std::size_t
1605	_M_get_bucket() const { return _M_bucket; } // for debug mode
1606	};
1607
1608	template<typename _Key, typename _Value, typename _ExtractKey,
1609	typename _H1, typename _H2, typename _Hash, bool __cache>
1610	inline bool
1611	operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
1612	_H1, _H2, _Hash, __cache>& __x,
1613	const _Local_iterator_base<_Key, _Value, _ExtractKey,
1614	_H1, _H2, _Hash, __cache>& __y)
1615	{ return __x._M_curr() == __y._M_curr(); }
1616
1617	template<typename _Key, typename _Value, typename _ExtractKey,
1618	typename _H1, typename _H2, typename _Hash, bool __cache>
1619	inline bool
1620	operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
1621	_H1, _H2, _Hash, __cache>& __x,
1622	const _Local_iterator_base<_Key, _Value, _ExtractKey,
1623	_H1, _H2, _Hash, __cache>& __y)
1624	{ return __x._M_curr() != __y._M_curr(); }
1625
1626	/// local iterators
1627	template<typename _Key, typename _Value, typename _ExtractKey,
1628	typename _H1, typename _H2, typename _Hash,
1629	bool __constant_iterators, bool __cache>
1630	struct _Local_iterator
1631	: public _Local_iterator_base<_Key, _Value, _ExtractKey,
1632	_H1, _H2, _Hash, __cache>
1633	{
1634	private:
1635	using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1636	_H1, _H2, _Hash, __cache>;
1637	using __hash_code_base = typename __base_type::__hash_code_base;
1638	public:
1639	typedef _Value value_type;
1640	typedef typename std::conditional<__constant_iterators,
1641	const _Value, _Value>::type
1642	pointer;
1643	typedef typename std::conditional<__constant_iterators,
1644	const _Value&, _Value&>::type
1645	reference;
1646	typedef std::ptrdiff_t difference_type;
1647	typedef std::forward_iterator_tag iterator_category;
1648
1649	_Local_iterator() = default;
1650
1651	_Local_iterator(const __hash_code_base& __base,
1652	_Hash_node<_Value, __cache>* __p,
1653	std::size_t __bkt, std::size_t __bkt_count)
1654	: __base_type(__base, __p, __bkt, __bkt_count)
1655	{ }
1656
1657	reference
1658	operator*() const
1659	{ return this->_M_cur->_M_v(); }
1660
1661	pointer
1662	operator->() const
1663	{ return this->_M_cur->_M_valptr(); }
1664
1665	_Local_iterator&
1666	operator++()
1667	{
1668	this->_M_incr();
1669	return *this;
1670	}
1671
1672	_Local_iterator
1673	operator++(int)
1674	{
1675	_Local_iterator __tmp(*this);
1676	this->_M_incr();
1677	return __tmp;
1678	}
1679	};
1680
1681	/// local const_iterators
1682	template<typename _Key, typename _Value, typename _ExtractKey,
1683	typename _H1, typename _H2, typename _Hash,
1684	bool __constant_iterators, bool __cache>
1685	struct _Local_const_iterator
1686	: public _Local_iterator_base<_Key, _Value, _ExtractKey,
1687	_H1, _H2, _Hash, __cache>
1688	{
1689	private:
1690	using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1691	_H1, _H2, _Hash, __cache>;
1692	using __hash_code_base = typename __base_type::__hash_code_base;
1693
1694	public:
1695	typedef _Value value_type;
1696	typedef const _Value* pointer;
1697	typedef const _Value& reference;
1698	typedef std::ptrdiff_t difference_type;
1699	typedef std::forward_iterator_tag iterator_category;
1700
1701	_Local_const_iterator() = default;
1702
1703	_Local_const_iterator(const __hash_code_base& __base,
1704	_Hash_node<_Value, __cache>* __p,
1705	std::size_t __bkt, std::size_t __bkt_count)
1706	: __base_type(__base, __p, __bkt, __bkt_count)
1707	{ }
1708
1709	_Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1710	_H1, _H2, _Hash,
1711	__constant_iterators,
1712	__cache>& __x)
1713	: __base_type(__x)
1714	{ }
1715
1716	reference
1717	operator*() const
1718	{ return this->_M_cur->_M_v(); }
1719
1720	pointer
1721	operator->() const
1722	{ return this->_M_cur->_M_valptr(); }
1723
1724	_Local_const_iterator&
1725	operator++()
1726	{
1727	this->_M_incr();
1728	return *this;
1729	}
1730
1731	_Local_const_iterator
1732	operator++(int)
1733	{
1734	_Local_const_iterator __tmp(*this);
1735	this->_M_incr();
1736	return __tmp;
1737	}
1738	};
1739
1740	/**
1741	* Primary class template _Hashtable_base.
1742	*
1743	* Helper class adding management of _Equal functor to
1744	* _Hash_code_base type.
1745	*
1746	* Base class templates are:
1747	* - __detail::_Hash_code_base
1748	* - __detail::_Hashtable_ebo_helper
1749	*/
1750	template<typename _Key, typename _Value,
1751	typename _ExtractKey, typename _Equal,
1752	typename _H1, typename _H2, typename _Hash, typename _Traits>
1753	struct _Hashtable_base
1754	: public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
1755	_Traits::__hash_cached::value>,
1756	private _Hashtable_ebo_helper<0, _Equal>
1757	{
1758	public:
1759	typedef _Key key_type;
1760	typedef _Value value_type;
1761	typedef _Equal key_equal;
1762	typedef std::size_t size_type;
1763	typedef std::ptrdiff_t difference_type;
1764
1765	using __traits_type = _Traits;
1766	using __hash_cached = typename __traits_type::__hash_cached;
1767	using __constant_iterators = typename __traits_type::__constant_iterators;
1768	using __unique_keys = typename __traits_type::__unique_keys;
1769
1770	using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1771	_H1, _H2, _Hash,
1772	__hash_cached::value>;
1773
1774	using __hash_code = typename __hash_code_base::__hash_code;
1775	using __node_type = typename __hash_code_base::__node_type;
1776
1777	using iterator = __detail::_Node_iterator<value_type,
1778	__constant_iterators::value,
1779	__hash_cached::value>;
1780
1781	using const_iterator = __detail::_Node_const_iterator<value_type,
1782	__constant_iterators::value,
1783	__hash_cached::value>;
1784
1785	using local_iterator = __detail::_Local_iterator<key_type, value_type,
1786	_ExtractKey, _H1, _H2, _Hash,
1787	__constant_iterators::value,
1788	__hash_cached::value>;
1789
1790	using const_local_iterator = __detail::_Local_const_iterator<key_type,
1791	value_type,
1792	_ExtractKey, _H1, _H2, _Hash,
1793	__constant_iterators::value,
1794	__hash_cached::value>;
1795
1796	using __ireturn_type = typename std::conditional<__unique_keys::value,
1797	std::pair<iterator, bool>,
1798	iterator>::type;
1799	private:
1800	using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1801	using _EqualHelper = _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
1802	__hash_code, __hash_cached::value>;
1803
1804	protected:
1805	_Hashtable_base() = default;
1806	_Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
1807	const _Hash& __hash, const _Equal& __eq)
1808	: __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
1809	{ }
1810
1811	bool
1812	_M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
1813	{
1814	return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
1815	__k, __c, __n);
1816	}
1817
1818	void
1819	_M_swap(_Hashtable_base& __x)
1820	{
1821	__hash_code_base::_M_swap(__x);
1822	std::swap(_M_eq(), __x._M_eq());
1823	}
1824
1825	const _Equal&
1826	_M_eq() const { return _EqualEBO::_S_cget(*this); }
1827
1828	_Equal&
1829	_M_eq() { return _EqualEBO::_S_get(*this); }
1830	};
1831
1832	/**
1833	* struct _Equality_base.
1834	*
1835	* Common types and functions for class _Equality.
1836	*/
1837	struct _Equality_base
1838	{
1839	protected:
1840	template<typename _Uiterator>
1841	static bool
1842	_S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
1843	};
1844
1845	// See std::is_permutation in N3068.
1846	template<typename _Uiterator>
1847	bool
1848	_Equality_base::
1849	_S_is_permutation(_Uiterator __first1, _Uiterator __last1,
1850	_Uiterator __first2)
1851	{
1852	for (; __first1 != __last1; ++__first1, ++__first2)
1853	if (!(__first1 == __first2))
1854	break;
1855
1856	if (__first1 == __last1)
1857	return true;
1858
1859	_Uiterator __last2 = __first2;
1860	std::advance(__last2, std::distance(__first1, __last1));
1861
1862	for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
1863	{
1864	_Uiterator __tmp = __first1;
1865	while (__tmp != __it1 && !bool(__tmp == __it1))
1866	++__tmp;
1867
1868	// We've seen this one before.
1869	if (__tmp != __it1)
1870	continue;
1871
1872	std::ptrdiff_t __n2 = 0;
1873	for (__tmp = __first2; __tmp != __last2; ++__tmp)
1874	if (__tmp == __it1)
1875	++__n2;
1876
1877	if (!__n2)
1878	return false;
1879
1880	std::ptrdiff_t __n1 = 0;
1881	for (__tmp = __it1; __tmp != __last1; ++__tmp)
1882	if (__tmp == __it1)
1883	++__n1;
1884
1885	if (__n1 != __n2)
1886	return false;
1887	}
1888	return true;
1889	}
1890
1891	/**
1892	* Primary class template _Equality.
1893	*
1894	* This is for implementing equality comparison for unordered
1895	* containers, per N3068, by John Lakos and Pablo Halpern.
1896	* Algorithmically, we follow closely the reference implementations
1897	* therein.
1898	*/
1899	template<typename _Key, typename _Value, typename _Alloc,
1900	typename _ExtractKey, typename _Equal,
1901	typename _H1, typename _H2, typename _Hash,
1902	typename _RehashPolicy, typename _Traits,
1903	bool _Unique_keys = _Traits::__unique_keys::value>
1904	struct _Equality;
1905
1906	/// Specialization.
1907	template<typename _Key, typename _Value, typename _Alloc,
1908	typename _ExtractKey, typename _Equal,
1909	typename _H1, typename _H2, typename _Hash,
1910	typename _RehashPolicy, typename _Traits>
1911	struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1912	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>
1913	{
1914	using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1915	_H1, _H2, _Hash, _RehashPolicy, _Traits>;
1916
1917	bool
1918	_M_equal(const __hashtable&) const;
1919	};
1920
1921	template<typename _Key, typename _Value, typename _Alloc,
1922	typename _ExtractKey, typename _Equal,
1923	typename _H1, typename _H2, typename _Hash,
1924	typename _RehashPolicy, typename _Traits>
1925	bool
1926	_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1927	_H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
1928	_M_equal(const __hashtable& __other) const
1929	{
1930	const __hashtable* __this = static_cast<const __hashtable*>(this);
1931
1932	if (__this->size() != __other.size())
1933	return false;
1934
1935	for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
1936	{
1937	const auto __ity = __other.find(_ExtractKey()(*__itx));
1938	if (__ity == __other.end() \|\| !bool(__ity == __itx))
1939	return false;
1940	}
1941	return true;
1942	}
1943
1944	/// Specialization.
1945	template<typename _Key, typename _Value, typename _Alloc,
1946	typename _ExtractKey, typename _Equal,
1947	typename _H1, typename _H2, typename _Hash,
1948	typename _RehashPolicy, typename _Traits>
1949	struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1950	_H1, _H2, _Hash, _RehashPolicy, _Traits, false>
1951	: public _Equality_base
1952	{
1953	using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1954	_H1, _H2, _Hash, _RehashPolicy, _Traits>;
1955
1956	bool
1957	_M_equal(const __hashtable&) const;
1958	};
1959
1960	template<typename _Key, typename _Value, typename _Alloc,
1961	typename _ExtractKey, typename _Equal,
1962	typename _H1, typename _H2, typename _Hash,
1963	typename _RehashPolicy, typename _Traits>
1964	bool
1965	_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1966	_H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
1967	_M_equal(const __hashtable& __other) const
1968	{
1969	const __hashtable* __this = static_cast<const __hashtable*>(this);
1970
1971	if (__this->size() != __other.size())
1972	return false;
1973
1974	for (auto __itx = __this->begin(); __itx != __this->end();)
1975	{
1976	const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
1977	const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
1978
1979	if (std::distance(__xrange.first, __xrange.second)
1980	!= std::distance(__yrange.first, __yrange.second))
1981	return false;
1982
1983	if (!_S_is_permutation(__xrange.first, __xrange.second,
1984	__yrange.first))
1985	return false;
1986
1987	__itx = __xrange.second;
1988	}
1989	return true;
1990	}
1991
1992	/**
1993	* This type deals with all allocation and keeps an allocator instance through
1994	* inheritance to benefit from EBO when possible.
1995	*/
1996	template<typename _NodeAlloc>
1997	struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
1998	{
1999	private:
2000	using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
2001	public:
2002	using __node_type = typename _NodeAlloc::value_type;
2003	using __node_alloc_type = _NodeAlloc;
2004	// Use __gnu_cxx to benefit from _S_always_equal and al.
2005	using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
2006
2007	using __value_type = typename __node_type::value_type;
2008	using __value_alloc_type =
2009	__alloc_rebind<__node_alloc_type, __value_type>;
2010	using __value_alloc_traits = std::allocator_traits<__value_alloc_type>;
2011
2012	using __node_base = __detail::_Hash_node_base;
2013	using __bucket_type = __node_base*;
2014	using __bucket_alloc_type =
2015	__alloc_rebind<__node_alloc_type, __bucket_type>;
2016	using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>;
2017
2018	_Hashtable_alloc() = default;
2019	_Hashtable_alloc(const _Hashtable_alloc&) = default;
2020	_Hashtable_alloc(_Hashtable_alloc&&) = default;
2021
2022	template<typename _Alloc>
2023	_Hashtable_alloc(_Alloc&& __a)
2024	: __ebo_node_alloc(std::forward<_Alloc>(__a))
2025	{ }
2026
2027	__node_alloc_type&
2028	_M_node_allocator()
2029	{ return __ebo_node_alloc::_S_get(*this); }
2030
2031	const __node_alloc_type&
2032	_M_node_allocator() const
2033	{ return __ebo_node_alloc::_S_cget(*this); }
2034
2035	template<typename... _Args>
2036	__node_type*
2037	_M_allocate_node(_Args&&... __args);
2038
2039	void
2040	_M_deallocate_node(__node_type* __n);
2041
2042	// Deallocate the linked list of nodes pointed to by __n
2043	void
2044	_M_deallocate_nodes(__node_type* __n);
2045
2046	__bucket_type*
2047	_M_allocate_buckets(std::size_t __n);
2048
2049	void
2050	_M_deallocate_buckets(__bucket_type*, std::size_t __n);
2051	};
2052
2053	// Definitions of class template _Hashtable_alloc's out-of-line member
2054	// functions.
2055	template<typename _NodeAlloc>
2056	template<typename... _Args>
2057	typename _Hashtable_alloc<_NodeAlloc>::__node_type*
2058	_Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
2059	{
2060	auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
2061	__node_type* __n = std::__addressof(*__nptr);
2062	__try
2063	{
2064	__value_alloc_type __a(_M_node_allocator());
2065	::new ((void*)__n) __node_type;
2066	__value_alloc_traits::construct(__a, __n->_M_valptr(),
2067	std::forward<_Args>(__args)...);
2068	return __n;
2069	}
2070	__catch(...)
2071	{
2072	__node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
2073	__throw_exception_again;
2074	}
2075	}
2076
2077	template<typename _NodeAlloc>
2078	void
2079	_Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
2080	{
2081	typedef typename __node_alloc_traits::pointer _Ptr;
2082	auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
2083	__value_alloc_type __a(_M_node_allocator());
2084	__value_alloc_traits::destroy(__a, __n->_M_valptr());
2085	__n->~__node_type();
2086	__node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
2087	}
2088
2089	template<typename _NodeAlloc>
2090	void
2091	_Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type* __n)
2092	{
2093	while (__n)
2094	{
2095	__node_type* __tmp = __n;
2096	__n = __n->_M_next();
2097	_M_deallocate_node(__tmp);
2098	}
2099	}
2100
2101	template<typename _NodeAlloc>
2102	typename _Hashtable_alloc<_NodeAlloc>::__bucket_type*
2103	_Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n)
2104	{
2105	__bucket_alloc_type __alloc(_M_node_allocator());
2106
2107	auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
2108	__bucket_type* __p = std::__addressof(*__ptr);
2109	__builtin_memset(__p, 0, __n * sizeof(__bucket_type));
2110	return __p;
2111	}
2112
2113	template<typename _NodeAlloc>
2114	void
2115	_Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts,
2116	std::size_t __n)
2117	{
2118	typedef typename __bucket_alloc_traits::pointer _Ptr;
2119	auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
2120	__bucket_alloc_type __alloc(_M_node_allocator());
2121	__bucket_alloc_traits::deallocate(__alloc, __ptr, __n);
2122	}
2123
2124	//@} hashtable-detail
2125	_GLIBCXX_END_NAMESPACE_VERSION
2126	} // namespace __detail
2127	} // namespace std
2128
2129	#endif // _HASHTABLE_POLICY_H
2130