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// hashtable.h header -*- C++ -*-
// Copyright (C) 2007-2019 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.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{unordered_map, unordered_set}
*/
#ifndef _HASHTABLE_H
#define _HASHTABLE_H 1
#pragma GCC system_header
#include <bits/hashtable_policy.h>
#if __cplusplus > 201402L
# include <bits/node_handle.h>
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, typename _Hash>
using __cache_default
= __not_<__and_<// Do not cache for fast hasher.
__is_fast_hash<_Hash>,
// Mandatory to have erase not throwing.
__is_nothrow_invocable<const _Hash&, const _Tp&>>>;
/**
* Primary class template _Hashtable.
*
* @ingroup hashtable-detail
*
* @tparam _Value CopyConstructible type.
*
* @tparam _Key CopyConstructible type.
*
* @tparam _Alloc An allocator type
* ([lib.allocator.requirements]) whose _Alloc::value_type is
* _Value. As a conforming extension, we allow for
* _Alloc::value_type != _Value.
*
* @tparam _ExtractKey Function object that takes an object of type
* _Value and returns a value of type _Key.
*
* @tparam _Equal Function object that takes two objects of type k
* and returns a bool-like value that is true if the two objects
* are considered equal.
*
* @tparam _H1 The hash function. A unary function object with
* argument type _Key and result type size_t. Return values should
* be distributed over the entire range [0, numeric_limits<size_t>:::max()].
*
* @tparam _H2 The range-hashing function (in the terminology of
* Tavori and Dreizin). A binary function object whose argument
* types and result type are all size_t. Given arguments r and N,
* the return value is in the range [0, N).
*
* @tparam _Hash The ranged hash function (Tavori and Dreizin). A
* binary function whose argument types are _Key and size_t and
* whose result type is size_t. Given arguments k and N, the
* return value is in the range [0, N). Default: hash(k, N) =
* h2(h1(k), N). If _Hash is anything other than the default, _H1
* and _H2 are ignored.
*
* @tparam _RehashPolicy Policy class with three members, all of
* which govern the bucket count. _M_next_bkt(n) returns a bucket
* count no smaller than n. _M_bkt_for_elements(n) returns a
* bucket count appropriate for an element count of n.
* _M_need_rehash(n_bkt, n_elt, n_ins) determines whether, if the
* current bucket count is n_bkt and the current element count is
* n_elt, we need to increase the bucket count. If so, returns
* make_pair(true, n), where n is the new bucket count. If not,
* returns make_pair(false, <anything>)
*
* @tparam _Traits Compile-time class with three boolean
* std::integral_constant members: __cache_hash_code, __constant_iterators,
* __unique_keys.
*
* Each _Hashtable data structure has:
*
* - _Bucket[] _M_buckets
* - _Hash_node_base _M_before_begin
* - size_type _M_bucket_count
* - size_type _M_element_count
*
* with _Bucket being _Hash_node* and _Hash_node containing:
*
* - _Hash_node* _M_next
* - Tp _M_value
* - size_t _M_hash_code if cache_hash_code is true
*
* In terms of Standard containers the hashtable is like the aggregation of:
*
* - std::forward_list<_Node> containing the elements
* - std::vector<std::forward_list<_Node>::iterator> representing the buckets
*
* The non-empty buckets contain the node before the first node in the
* bucket. This design makes it possible to implement something like a
* std::forward_list::insert_after on container insertion and
* std::forward_list::erase_after on container erase
* calls. _M_before_begin is equivalent to
* std::forward_list::before_begin. Empty buckets contain
* nullptr. Note that one of the non-empty buckets contains
* &_M_before_begin which is not a dereferenceable node so the
* node pointer in a bucket shall never be dereferenced, only its
* next node can be.
*
* Walking through a bucket's nodes requires a check on the hash code to
* see if each node is still in the bucket. Such a design assumes a
* quite efficient hash functor and is one of the reasons it is
* highly advisable to set __cache_hash_code to true.
*
* The container iterators are simply built from nodes. This way
* incrementing the iterator is perfectly efficient independent of
* how many empty buckets there are in the container.
*
* On insert we compute the element's hash code and use it to find the
* bucket index. If the element must be inserted in an empty bucket
* we add it at the beginning of the singly linked list and make the
* bucket point to _M_before_begin. The bucket that used to point to
* _M_before_begin, if any, is updated to point to its new before
* begin node.
*
* On erase, the simple iterator design requires using the hash
* functor to get the index of the bucket to update. For this
* reason, when __cache_hash_code is set to false the hash functor must
* not throw and this is enforced by a static assertion.
*
* Functionality is implemented by decomposition into base classes,
* where the derived _Hashtable class is used in _Map_base,
* _Insert, _Rehash_base, and _Equality base classes to access the
* "this" pointer. _Hashtable_base is used in the base classes as a
* non-recursive, fully-completed-type so that detailed nested type
* information, such as iterator type and node type, can be
* used. This is similar to the "Curiously Recurring Template
* Pattern" (CRTP) technique, but uses a reconstructed, not
* explicitly passed, template pattern.
*
* Base class templates are:
* - __detail::_Hashtable_base
* - __detail::_Map_base
* - __detail::_Insert
* - __detail::_Rehash_base
* - __detail::_Equality
*/
template<typename _Key, typename _Value, typename _Alloc,
typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash,
typename _RehashPolicy, typename _Traits>
class _Hashtable
: public __detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal,
_H1, _H2, _Hash, _Traits>,
public __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>,
public __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>,
public __detail::_Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>,
public __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>,
private __detail::_Hashtable_alloc<
__alloc_rebind<_Alloc,
__detail::_Hash_node<_Value,
_Traits::__hash_cached::value>>>
{
static_assert(is_same<typename remove_cv<_Value>::type, _Value>::value,
"unordered container must have a non-const, non-volatile value_type");
#ifdef __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Value>{},
"unordered container must have the same value_type as its allocator");
#endif
using __traits_type = _Traits;
using __hash_cached = typename __traits_type::__hash_cached;
using __node_type = __detail::_Hash_node<_Value, __hash_cached::value>;
using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
using __hashtable_alloc = __detail::_Hashtable_alloc<__node_alloc_type>;
using __value_alloc_traits =
typename __hashtable_alloc::__value_alloc_traits;
using __node_alloc_traits =
typename __hashtable_alloc::__node_alloc_traits;
using __node_base = typename __hashtable_alloc::__node_base;
using __bucket_type = typename __hashtable_alloc::__bucket_type;
public:
typedef _Key key_type;
typedef _Value value_type;
typedef _Alloc allocator_type;
typedef _Equal key_equal;
// mapped_type, if present, comes from _Map_base.
// hasher, if present, comes from _Hash_code_base/_Hashtable_base.
typedef typename __value_alloc_traits::pointer pointer;
typedef typename __value_alloc_traits::const_pointer const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
private:
using __rehash_type = _RehashPolicy;
using __rehash_state = typename __rehash_type::_State;
using __constant_iterators = typename __traits_type::__constant_iterators;
using __unique_keys = typename __traits_type::__unique_keys;
using __key_extract = typename std::conditional<
__constant_iterators::value,
__detail::_Identity,
__detail::_Select1st>::type;
using __hashtable_base = __detail::
_Hashtable_base<_Key, _Value, _ExtractKey,
_Equal, _H1, _H2, _Hash, _Traits>;
using __hash_code_base = typename __hashtable_base::__hash_code_base;
using __hash_code = typename __hashtable_base::__hash_code;
using __ireturn_type = typename __hashtable_base::__ireturn_type;
using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
_Equal, _H1, _H2, _Hash,
_RehashPolicy, _Traits>;
using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
_ExtractKey, _Equal,
_H1, _H2, _Hash,
_RehashPolicy, _Traits>;
using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
_Equal, _H1, _H2, _Hash,
_RehashPolicy, _Traits>;
using __reuse_or_alloc_node_type =
__detail::_ReuseOrAllocNode<__node_alloc_type>;
// Metaprogramming for picking apart hash caching.
template<typename _Cond>
using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
template<typename _Cond>
using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
// Compile-time diagnostics.
// _Hash_code_base has everything protected, so use this derived type to
// access it.
struct __hash_code_base_access : __hash_code_base
{ using __hash_code_base::_M_bucket_index; };
// Getting a bucket index from a node shall not throw because it is used
// in methods (erase, swap...) that shall not throw.
static_assert(noexcept(declval<const __hash_code_base_access&>()
._M_bucket_index((const __node_type*)nullptr,
(std::size_t)0)),
"Cache the hash code or qualify your functors involved"
" in hash code and bucket index computation with noexcept");
// Following two static assertions are necessary to guarantee
// that local_iterator will be default constructible.
// When hash codes are cached local iterator inherits from H2 functor
// which must then be default constructible.
static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
"Functor used to map hash code to bucket index"
" must be default constructible");
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _H1a, typename _H2a, typename _Hasha,
typename _RehashPolicya, typename _Traitsa,
bool _Unique_keysa>
friend struct __detail::_Map_base;
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _H1a, typename _H2a, typename _Hasha,
typename _RehashPolicya, typename _Traitsa>
friend struct __detail::_Insert_base;
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _H1a, typename _H2a, typename _Hasha,
typename _RehashPolicya, typename _Traitsa,
bool _Constant_iteratorsa>
friend struct __detail::_Insert;
public:
using size_type = typename __hashtable_base::size_type;
using difference_type = typename __hashtable_base::difference_type;
using iterator = typename __hashtable_base::iterator;
using const_iterator = typename __hashtable_base::const_iterator;
using local_iterator = typename __hashtable_base::local_iterator;
using const_local_iterator = typename __hashtable_base::
const_local_iterator;
#if __cplusplus > 201402L
using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
using insert_return_type = _Node_insert_return<iterator, node_type>;
#endif
private:
__bucket_type* _M_buckets = &_M_single_bucket;
size_type _M_bucket_count = 1;
__node_base _M_before_begin;
size_type _M_element_count = 0;
_RehashPolicy _M_rehash_policy;
// A single bucket used when only need for 1 bucket. Especially
// interesting in move semantic to leave hashtable with only 1 buckets
// which is not allocated so that we can have those operations noexcept
// qualified.
// Note that we can't leave hashtable with 0 bucket without adding
// numerous checks in the code to avoid 0 modulus.
__bucket_type _M_single_bucket = nullptr;
bool
_M_uses_single_bucket(__bucket_type* __bkts) const
{ return __builtin_expect(__bkts == &_M_single_bucket, false); }
bool
_M_uses_single_bucket() const
{ return _M_uses_single_bucket(_M_buckets); }
__hashtable_alloc&
_M_base_alloc() { return *this; }
__bucket_type*
_M_allocate_buckets(size_type __n)
{
if (__builtin_expect(__n == 1, false))
{
_M_single_bucket = nullptr;
return &_M_single_bucket;
}
return __hashtable_alloc::_M_allocate_buckets(__n);
}
void
_M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
{
if (_M_uses_single_bucket(__bkts))
return;
__hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
}
void
_M_deallocate_buckets()
{ _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
// Gets bucket begin, deals with the fact that non-empty buckets contain
// their before begin node.
__node_type*
_M_bucket_begin(size_type __bkt) const;
__node_type*
_M_begin() const
{ return static_cast<__node_type*>(_M_before_begin._M_nxt); }
// Assign *this using another _Hashtable instance. Either elements
// are copy or move depends on the _NodeGenerator.
template<typename _Ht, typename _NodeGenerator>
void
_M_assign_elements(_Ht&&, const _NodeGenerator&);
template<typename _NodeGenerator>
void
_M_assign(const _Hashtable&, const _NodeGenerator&);
void
_M_move_assign(_Hashtable&&, std::true_type);
void
_M_move_assign(_Hashtable&&, std::false_type);
void
_M_reset() noexcept;
_Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
const _Equal& __eq, const _ExtractKey& __exk,
const allocator_type& __a)
: __hashtable_base(__exk, __h1, __h2, __h, __eq),
__hashtable_alloc(__node_alloc_type(__a))
{ }
public:
// Constructor, destructor, assignment, swap
_Hashtable() = default;
_Hashtable(size_type __bucket_hint,
const _H1&, const _H2&, const _Hash&,
const _Equal&, const _ExtractKey&,
const allocator_type&);
template<typename _InputIterator>
_Hashtable(_InputIterator __first, _InputIterator __last,
size_type __bucket_hint,
const _H1&, const _H2&, const _Hash&,
const _Equal&, const _ExtractKey&,
const allocator_type&);
_Hashtable(const _Hashtable&);
_Hashtable(_Hashtable&&) noexcept;
_Hashtable(const _Hashtable&, const allocator_type&);
_Hashtable(_Hashtable&&, const allocator_type&);
// Use delegating constructors.
explicit
_Hashtable(const allocator_type& __a)
: __hashtable_alloc(__node_alloc_type(__a))
{ }
explicit
_Hashtable(size_type __n,
const _H1& __hf = _H1(),
const key_equal& __eql = key_equal(),
const allocator_type& __a = allocator_type())
: _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
__key_extract(), __a)
{ }
template<typename _InputIterator>
_Hashtable(_InputIterator __f, _InputIterator __l,
size_type __n = 0,
const _H1& __hf = _H1(),
const key_equal& __eql = key_equal(),
const allocator_type& __a = allocator_type())
: _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
__key_extract(), __a)
{ }
_Hashtable(initializer_list<value_type> __l,
size_type __n = 0,
const _H1& __hf = _H1(),
const key_equal& __eql = key_equal(),
const allocator_type& __a = allocator_type())
: _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
__key_extract(), __a)
{ }
_Hashtable&
operator=(const _Hashtable& __ht);
_Hashtable&
operator=(_Hashtable&& __ht)
noexcept(__node_alloc_traits::_S_nothrow_move()
&& is_nothrow_move_assignable<_H1>::value
&& is_nothrow_move_assignable<_Equal>::value)
{
constexpr bool __move_storage =
__node_alloc_traits::_S_propagate_on_move_assign()
|| __node_alloc_traits::_S_always_equal();
_M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
return *this;
}
_Hashtable&
operator=(initializer_list<value_type> __l)
{
__reuse_or_alloc_node_type __roan(_M_begin(), *this);
_M_before_begin._M_nxt = nullptr;
clear();
this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys());
return *this;
}
~_Hashtable() noexcept;
void
swap(_Hashtable&)
noexcept(__and_<__is_nothrow_swappable<_H1>,
__is_nothrow_swappable<_Equal>>::value);
// Basic container operations
iterator
begin() noexcept
{ return iterator(_M_begin()); }
const_iterator
begin() const noexcept
{ return const_iterator(_M_begin()); }
iterator
end() noexcept
{ return iterator(nullptr); }
const_iterator
end() const noexcept
{ return const_iterator(nullptr); }
const_iterator
cbegin() const noexcept
{ return const_iterator(_M_begin()); }
const_iterator
cend() const noexcept
{ return const_iterator(nullptr); }
size_type
size() const noexcept
{ return _M_element_count; }
_GLIBCXX_NODISCARD bool
empty() const noexcept
{ return size() == 0; }
allocator_type
get_allocator() const noexcept
{ return allocator_type(this->_M_node_allocator()); }
size_type
max_size() const noexcept
{ return __node_alloc_traits::max_size(this->_M_node_allocator()); }
// Observers
key_equal
key_eq() const
{ return this->_M_eq(); }
// hash_function, if present, comes from _Hash_code_base.
// Bucket operations
size_type
bucket_count() const noexcept
{ return _M_bucket_count; }
size_type
max_bucket_count() const noexcept
{ return max_size(); }
size_type
bucket_size(size_type __n) const
{ return std::distance(begin(__n), end(__n)); }
size_type
bucket(const key_type& __k) const
{ return _M_bucket_index(__k, this->_M_hash_code(__k)); }
local_iterator
begin(size_type __n)
{
return local_iterator(*this, _M_bucket_begin(__n),
__n, _M_bucket_count);
}
local_iterator
end(size_type __n)
{ return local_iterator(*this, nullptr, __n, _M_bucket_count); }
const_local_iterator
begin(size_type __n) const
{
return const_local_iterator(*this, _M_bucket_begin(__n),
__n, _M_bucket_count);
}
const_local_iterator
end(size_type __n) const
{ return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
// DR 691.
const_local_iterator
cbegin(size_type __n) const
{
return const_local_iterator(*this, _M_bucket_begin(__n),
__n, _M_bucket_count);
}
const_local_iterator
cend(size_type __n) const
{ return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
float
load_factor() const noexcept
{
return static_cast<float>(size()) / static_cast<float>(bucket_count());
}
// max_load_factor, if present, comes from _Rehash_base.
// Generalization of max_load_factor. Extension, not found in
// TR1. Only useful if _RehashPolicy is something other than
// the default.
const _RehashPolicy&
__rehash_policy() const
{ return _M_rehash_policy; }
void
__rehash_policy(const _RehashPolicy& __pol)
{ _M_rehash_policy = __pol; }
// Lookup.
iterator
find(const key_type& __k);
const_iterator
find(const key_type& __k) const;
size_type
count(const key_type& __k) const;
std::pair<iterator, iterator>
equal_range(const key_type& __k);
std::pair<const_iterator, const_iterator>
equal_range(const key_type& __k) const;
protected:
// Bucket index computation helpers.
size_type
_M_bucket_index(__node_type* __n) const noexcept
{ return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
size_type
_M_bucket_index(const key_type& __k, __hash_code __c) const
{ return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
// Find and insert helper functions and types
// Find the node before the one matching the criteria.
__node_base*
_M_find_before_node(size_type, const key_type&, __hash_code) const;
__node_type*
_M_find_node(size_type __bkt, const key_type& __key,
__hash_code __c) const
{
__node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
if (__before_n)
return static_cast<__node_type*>(__before_n->_M_nxt);
return nullptr;
}
// Insert a node at the beginning of a bucket.
void
_M_insert_bucket_begin(size_type, __node_type*);
// Remove the bucket first node
void
_M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
size_type __next_bkt);
// Get the node before __n in the bucket __bkt
__node_base*
_M_get_previous_node(size_type __bkt, __node_base* __n);
// Insert node with hash code __code, in bucket bkt if no rehash (assumes
// no element with its key already present). Take ownership of the node,
// deallocate it on exception.
iterator
_M_insert_unique_node(size_type __bkt, __hash_code __code,
__node_type* __n, size_type __n_elt = 1);
// Insert node with hash code __code. Take ownership of the node,
// deallocate it on exception.
iterator
_M_insert_multi_node(__node_type* __hint,
__hash_code __code, __node_type* __n);
template<typename... _Args>
std::pair<iterator, bool>
_M_emplace(std::true_type, _Args&&... __args);
template<typename... _Args>
iterator
_M_emplace(std::false_type __uk, _Args&&... __args)
{ return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
// Emplace with hint, useless when keys are unique.
template<typename... _Args>
iterator
_M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
{ return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
template<typename... _Args>
iterator
_M_emplace(const_iterator, std::false_type, _Args&&... __args);
template<typename _Arg, typename _NodeGenerator>
std::pair<iterator, bool>
_M_insert(_Arg&&, const _NodeGenerator&, true_type, size_type = 1);
template<typename _Arg, typename _NodeGenerator>
iterator
_M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
false_type __uk)
{
return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
__uk);
}
// Insert with hint, not used when keys are unique.
template<typename _Arg, typename _NodeGenerator>
iterator
_M_insert(const_iterator, _Arg&& __arg,
const _NodeGenerator& __node_gen, true_type __uk)
{
return
_M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
}
// Insert with hint when keys are not unique.
template<typename _Arg, typename _NodeGenerator>
iterator
_M_insert(const_iterator, _Arg&&,
const _NodeGenerator&, false_type);
size_type
_M_erase(std::true_type, const key_type&);
size_type
_M_erase(std::false_type, const key_type&);
iterator
_M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
public:
// Emplace
template<typename... _Args>
__ireturn_type
emplace(_Args&&... __args)
{ return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
template<typename... _Args>
iterator
emplace_hint(const_iterator __hint, _Args&&... __args)
{
return _M_emplace(__hint, __unique_keys(),
std::forward<_Args>(__args)...);
}
// Insert member functions via inheritance.
// Erase
iterator
erase(const_iterator);
// LWG 2059.
iterator
erase(iterator __it)
{ return erase(const_iterator(__it)); }
size_type
erase(const key_type& __k)
{ return _M_erase(__unique_keys(), __k); }
iterator
erase(const_iterator, const_iterator);
void
clear() noexcept;
// Set number of buckets to be appropriate for container of n element.
void rehash(size_type __n);
// DR 1189.
// reserve, if present, comes from _Rehash_base.
#if __cplusplus > 201402L
/// Re-insert an extracted node into a container with unique keys.
insert_return_type
_M_reinsert_node(node_type&& __nh)
{
insert_return_type __ret;
if (__nh.empty())
__ret.position = end();
else
{
__glibcxx_assert(get_allocator() == __nh.get_allocator());
const key_type& __k = __nh._M_key();
__hash_code __code = this->_M_hash_code(__k);
size_type __bkt = _M_bucket_index(__k, __code);
if (__node_type* __n = _M_find_node(__bkt, __k, __code))
{
__ret.node = std::move(__nh);
__ret.position = iterator(__n);
__ret.inserted = false;
}
else
{
__ret.position
= _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
__nh._M_ptr = nullptr;
__ret.inserted = true;
}
}
return __ret;
}
/// Re-insert an extracted node into a container with equivalent keys.
iterator
_M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
{
iterator __ret;
if (__nh.empty())
__ret = end();
else
{
__glibcxx_assert(get_allocator() == __nh.get_allocator());
auto __code = this->_M_hash_code(__nh._M_key());
auto __node = std::exchange(__nh._M_ptr, nullptr);
// FIXME: this deallocates the node on exception.
__ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
}
return __ret;
}
/// Extract a node.
node_type
extract(const_iterator __pos)
{
__node_type* __n = __pos._M_cur;
size_t __bkt = _M_bucket_index(__n);
// Look for previous node to unlink it from the erased one, this
// is why we need buckets to contain the before begin to make
// this search fast.
__node_base* __prev_n = _M_get_previous_node(__bkt, __n);
if (__prev_n == _M_buckets[__bkt])
_M_remove_bucket_begin(__bkt, __n->_M_next(),
__n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
else if (__n->_M_nxt)
{
size_type __next_bkt = _M_bucket_index(__n->_M_next());
if (__next_bkt != __bkt)
_M_buckets[__next_bkt] = __prev_n;
}
__prev_n->_M_nxt = __n->_M_nxt;
__n->_M_nxt = nullptr;
--_M_element_count;
return { __n, this->_M_node_allocator() };
}
/// Extract a node.
node_type
extract(const _Key& __k)
{
node_type __nh;
auto __pos = find(__k);
if (__pos != end())
__nh = extract(const_iterator(__pos));
return __nh;
}
/// Merge from a compatible container into one with unique keys.
template<typename _Compatible_Hashtable>
void
_M_merge_unique(_Compatible_Hashtable& __src) noexcept
{
static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
node_type>, "Node types are compatible");
__glibcxx_assert(get_allocator() == __src.get_allocator());
auto __n_elt = __src.size();
for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
{
auto __pos = __i++;
const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
__hash_code __code = this->_M_hash_code(__k);
size_type __bkt = _M_bucket_index(__k, __code);
if (_M_find_node(__bkt, __k, __code) == nullptr)
{
auto __nh = __src.extract(__pos);
_M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
__nh._M_ptr = nullptr;
__n_elt = 1;
}
else if (__n_elt != 1)
--__n_elt;
}
}
/// Merge from a compatible container into one with equivalent keys.
template<typename _Compatible_Hashtable>
void
_M_merge_multi(_Compatible_Hashtable& __src) noexcept
{
static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
node_type>, "Node types are compatible");
__glibcxx_assert(get_allocator() == __src.get_allocator());
this->reserve(size() + __src.size());
for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
_M_reinsert_node_multi(cend(), __src.extract(__i++));
}
#endif // C++17
private:
// Helper rehash method used when keys are unique.
void _M_rehash_aux(size_type __n, std::true_type);
// Helper rehash method used when keys can be non-unique.
void _M_rehash_aux(size_type __n, std::false_type);
// Unconditionally change size of bucket array to n, restore
// hash policy state to __state on exception.
void _M_rehash(size_type __n, const __rehash_state& __state);
};
// Definitions of class template _Hashtable's out-of-line member functions.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_bucket_begin(size_type __bkt) const
-> __node_type*
{
__node_base* __n = _M_buckets[__bkt];
return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_Hashtable(size_type __bucket_hint,
const _H1& __h1, const _H2& __h2, const _Hash& __h,
const _Equal& __eq, const _ExtractKey& __exk,
const allocator_type& __a)
: _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
{
auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
if (__bkt > _M_bucket_count)
{
_M_buckets = _M_allocate_buckets(__bkt);
_M_bucket_count = __bkt;
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename _InputIterator>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_Hashtable(_InputIterator __f, _InputIterator __l,
size_type __bucket_hint,
const _H1& __h1, const _H2& __h2, const _Hash& __h,
const _Equal& __eq, const _ExtractKey& __exk,
const allocator_type& __a)
: _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
{
auto __nb_elems = __detail::__distance_fw(__f, __l);
auto __bkt_count =
_M_rehash_policy._M_next_bkt(
std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
__bucket_hint));
if (__bkt_count > _M_bucket_count)
{
_M_buckets = _M_allocate_buckets(__bkt_count);
_M_bucket_count = __bkt_count;
}
for (; __f != __l; ++__f)
this->insert(*__f);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
operator=(const _Hashtable& __ht)
-> _Hashtable&
{
if (&__ht == this)
return *this;
if (__node_alloc_traits::_S_propagate_on_copy_assign())
{
auto& __this_alloc = this->_M_node_allocator();
auto& __that_alloc = __ht._M_node_allocator();
if (!__node_alloc_traits::_S_always_equal()
&& __this_alloc != __that_alloc)
{
// Replacement allocator cannot free existing storage.
this->_M_deallocate_nodes(_M_begin());
_M_before_begin._M_nxt = nullptr;
_M_deallocate_buckets();
_M_buckets = nullptr;
std::__alloc_on_copy(__this_alloc, __that_alloc);
__hashtable_base::operator=(__ht);
_M_bucket_count = __ht._M_bucket_count;
_M_element_count = __ht._M_element_count;
_M_rehash_policy = __ht._M_rehash_policy;
__try
{
_M_assign(__ht,
[this](const __node_type* __n)
{ return this->_M_allocate_node(__n->_M_v()); });
}
__catch(...)
{
// _M_assign took care of deallocating all memory. Now we
// must make sure this instance remains in a usable state.
_M_reset();
__throw_exception_again;
}
return *this;
}
std::__alloc_on_copy(__this_alloc, __that_alloc);
}
// Reuse allocated buckets and nodes.
_M_assign_elements(__ht,
[](const __reuse_or_alloc_node_type& __roan, const __node_type* __n)
{ return __roan(__n->_M_v()); });
return *this;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename _Ht, typename _NodeGenerator>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_assign_elements(_Ht&& __ht, const _NodeGenerator& __node_gen)
{
__bucket_type* __former_buckets = nullptr;
std::size_t __former_bucket_count = _M_bucket_count;
const __rehash_state& __former_state = _M_rehash_policy._M_state();
if (_M_bucket_count != __ht._M_bucket_count)
{
__former_buckets = _M_buckets;
_M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
_M_bucket_count = __ht._M_bucket_count;
}
else
__builtin_memset(_M_buckets, 0,
_M_bucket_count * sizeof(__bucket_type));
__try
{
__hashtable_base::operator=(std::forward<_Ht>(__ht));
_M_element_count = __ht._M_element_count;
_M_rehash_policy = __ht._M_rehash_policy;
__reuse_or_alloc_node_type __roan(_M_begin(), *this);
_M_before_begin._M_nxt = nullptr;
_M_assign(__ht,
[&__node_gen, &__roan](__node_type* __n)
{ return __node_gen(__roan, __n); });
if (__former_buckets)
_M_deallocate_buckets(__former_buckets, __former_bucket_count);
}
__catch(...)
{
if (__former_buckets)
{
// Restore previous buckets.
_M_deallocate_buckets();
_M_rehash_policy._M_reset(__former_state);
_M_buckets = __former_buckets;
_M_bucket_count = __former_bucket_count;
}
__builtin_memset(_M_buckets, 0,
_M_bucket_count * sizeof(__bucket_type));
__throw_exception_again;
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename _NodeGenerator>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
{
__bucket_type* __buckets = nullptr;
if (!_M_buckets)
_M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
__try
{
if (!__ht._M_before_begin._M_nxt)
return;
// First deal with the special first node pointed to by
// _M_before_begin.
__node_type* __ht_n = __ht._M_begin();
__node_type* __this_n = __node_gen(__ht_n);
this->_M_copy_code(__this_n, __ht_n);
_M_before_begin._M_nxt = __this_n;
_M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
// Then deal with other nodes.
__node_base* __prev_n = __this_n;
for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
{
__this_n = __node_gen(__ht_n);
__prev_n->_M_nxt = __this_n;
this->_M_copy_code(__this_n, __ht_n);
size_type __bkt = _M_bucket_index(__this_n);
if (!_M_buckets[__bkt])
_M_buckets[__bkt] = __prev_n;
__prev_n = __this_n;
}
}
__catch(...)
{
clear();
if (__buckets)
_M_deallocate_buckets();
__throw_exception_again;
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_reset() noexcept
{
_M_rehash_policy._M_reset();
_M_bucket_count = 1;
_M_single_bucket = nullptr;
_M_buckets = &_M_single_bucket;
_M_before_begin._M_nxt = nullptr;
_M_element_count = 0;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_move_assign(_Hashtable&& __ht, std::true_type)
{
this->_M_deallocate_nodes(_M_begin());
_M_deallocate_buckets();
__hashtable_base::operator=(std::move(__ht));
_M_rehash_policy = __ht._M_rehash_policy;
if (!__ht._M_uses_single_bucket())
_M_buckets = __ht._M_buckets;
else
{
_M_buckets = &_M_single_bucket;
_M_single_bucket = __ht._M_single_bucket;
}
_M_bucket_count = __ht._M_bucket_count;
_M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
_M_element_count = __ht._M_element_count;
std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
// Fix buckets containing the _M_before_begin pointers that can't be
// moved.
if (_M_begin())
_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
__ht._M_reset();
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_move_assign(_Hashtable&& __ht, std::false_type)
{
if (__ht._M_node_allocator() == this->_M_node_allocator())
_M_move_assign(std::move(__ht), std::true_type());
else
{
// Can't move memory, move elements then.
_M_assign_elements(std::move(__ht),
[](const __reuse_or_alloc_node_type& __roan, __node_type* __n)
{ return __roan(std::move_if_noexcept(__n->_M_v())); });
__ht.clear();
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_Hashtable(const _Hashtable& __ht)
: __hashtable_base(__ht),
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(
__node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
_M_buckets(nullptr),
_M_bucket_count(__ht._M_bucket_count),
_M_element_count(__ht._M_element_count),
_M_rehash_policy(__ht._M_rehash_policy)
{
_M_assign(__ht,
[this](const __node_type* __n)
{ return this->_M_allocate_node(__n->_M_v()); });
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_Hashtable(_Hashtable&& __ht) noexcept
: __hashtable_base(__ht),
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(std::move(__ht._M_base_alloc())),
_M_buckets(__ht._M_buckets),
_M_bucket_count(__ht._M_bucket_count),
_M_before_begin(__ht._M_before_begin._M_nxt),
_M_element_count(__ht._M_element_count),
_M_rehash_policy(__ht._M_rehash_policy)
{
// Update, if necessary, buckets if __ht is using its single bucket.
if (__ht._M_uses_single_bucket())
{
_M_buckets = &_M_single_bucket;
_M_single_bucket = __ht._M_single_bucket;
}
// Update, if necessary, bucket pointing to before begin that hasn't
// moved.
if (_M_begin())
_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
__ht._M_reset();
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_Hashtable(const _Hashtable& __ht, const allocator_type& __a)
: __hashtable_base(__ht),
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(__node_alloc_type(__a)),
_M_buckets(),
_M_bucket_count(__ht._M_bucket_count),
_M_element_count(__ht._M_element_count),
_M_rehash_policy(__ht._M_rehash_policy)
{
_M_assign(__ht,
[this](const __node_type* __n)
{ return this->_M_allocate_node(__n->_M_v()); });
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_Hashtable(_Hashtable&& __ht, const allocator_type& __a)
: __hashtable_base(__ht),
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(__node_alloc_type(__a)),
_M_buckets(nullptr),
_M_bucket_count(__ht._M_bucket_count),
_M_element_count(__ht._M_element_count),
_M_rehash_policy(__ht._M_rehash_policy)
{
if (__ht._M_node_allocator() == this->_M_node_allocator())
{
if (__ht._M_uses_single_bucket())
{
_M_buckets = &_M_single_bucket;
_M_single_bucket = __ht._M_single_bucket;
}
else
_M_buckets = __ht._M_buckets;
_M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
// Update, if necessary, bucket pointing to before begin that hasn't
// moved.
if (_M_begin())
_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
__ht._M_reset();
}
else
{
_M_assign(__ht,
[this](__node_type* __n)
{
return this->_M_allocate_node(
std::move_if_noexcept(__n->_M_v()));
});
__ht.clear();
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
~_Hashtable() noexcept
{
clear();
_M_deallocate_buckets();
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
swap(_Hashtable& __x)
noexcept(__and_<__is_nothrow_swappable<_H1>,
__is_nothrow_swappable<_Equal>>::value)
{
// The only base class with member variables is hash_code_base.
// We define _Hash_code_base::_M_swap because different
// specializations have different members.
this->_M_swap(__x);
std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
std::swap(_M_rehash_policy, __x._M_rehash_policy);
// Deal properly with potentially moved instances.
if (this->_M_uses_single_bucket())
{
if (!__x._M_uses_single_bucket())
{
_M_buckets = __x._M_buckets;
__x._M_buckets = &__x._M_single_bucket;
}
}
else if (__x._M_uses_single_bucket())
{
__x._M_buckets = _M_buckets;
_M_buckets = &_M_single_bucket;
}
else
std::swap(_M_buckets, __x._M_buckets);
std::swap(_M_bucket_count, __x._M_bucket_count);
std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
std::swap(_M_element_count, __x._M_element_count);
std::swap(_M_single_bucket, __x._M_single_bucket);
// Fix buckets containing the _M_before_begin pointers that can't be
// swapped.
if (_M_begin())
_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
if (__x._M_begin())
__x._M_buckets[__x._M_bucket_index(__x._M_begin())]
= &__x._M_before_begin;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
find(const key_type& __k)
-> iterator
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
return __p ? iterator(__p) : end();
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
find(const key_type& __k) const
-> const_iterator
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
return __p ? const_iterator(__p) : end();
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
count(const key_type& __k) const
-> size_type
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_bucket_begin(__n);
if (!__p)
return 0;
std::size_t __result = 0;
for (;; __p = __p->_M_next())
{
if (this->_M_equals(__k, __code, __p))
++__result;
else if (__result)
// All equivalent values are next to each other, if we
// found a non-equivalent value after an equivalent one it
// means that we won't find any new equivalent value.
break;
if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
break;
}
return __result;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
equal_range(const key_type& __k)
-> pair<iterator, iterator>
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
if (__p)
{
__node_type* __p1 = __p->_M_next();
while (__p1 && _M_bucket_index(__p1) == __n
&& this->_M_equals(__k, __code, __p1))
__p1 = __p1->_M_next();
return std::make_pair(iterator(__p), iterator(__p1));
}
else
return std::make_pair(end(), end());
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
equal_range(const key_type& __k) const
-> pair<const_iterator, const_iterator>
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
if (__p)
{
__node_type* __p1 = __p->_M_next();
while (__p1 && _M_bucket_index(__p1) == __n
&& this->_M_equals(__k, __code, __p1))
__p1 = __p1->_M_next();
return std::make_pair(const_iterator(__p), const_iterator(__p1));
}
else
return std::make_pair(end(), end());
}
// Find the node whose key compares equal to k in the bucket n.
// Return nullptr if no node is found.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_find_before_node(size_type __n, const key_type& __k,
__hash_code __code) const
-> __node_base*
{
__node_base* __prev_p = _M_buckets[__n];
if (!__prev_p)
return nullptr;
for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
__p = __p->_M_next())
{
if (this->_M_equals(__k, __code, __p))
return __prev_p;
if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
break;
__prev_p = __p;
}
return nullptr;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_insert_bucket_begin(size_type __bkt, __node_type* __node)
{
if (_M_buckets[__bkt])
{
// Bucket is not empty, we just need to insert the new node
// after the bucket before begin.
__node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
_M_buckets[__bkt]->_M_nxt = __node;
}
else
{
// The bucket is empty, the new node is inserted at the
// beginning of the singly-linked list and the bucket will
// contain _M_before_begin pointer.
__node->_M_nxt = _M_before_begin._M_nxt;
_M_before_begin._M_nxt = __node;
if (__node->_M_nxt)
// We must update former begin bucket that is pointing to
// _M_before_begin.
_M_buckets[_M_bucket_index(__node->_M_next())] = __node;
_M_buckets[__bkt] = &_M_before_begin;
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_remove_bucket_begin(size_type __bkt, __node_type* __next,
size_type __next_bkt)
{
if (!__next || __next_bkt != __bkt)
{
// Bucket is now empty
// First update next bucket if any
if (__next)
_M_buckets[__next_bkt] = _M_buckets[__bkt];
// Second update before begin node if necessary
if (&_M_before_begin == _M_buckets[__bkt])
_M_before_begin._M_nxt = __next;
_M_buckets[__bkt] = nullptr;
}
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_get_previous_node(size_type __bkt, __node_base* __n)
-> __node_base*
{
__node_base* __prev_n = _M_buckets[__bkt];
while (__prev_n->_M_nxt != __n)
__prev_n = __prev_n->_M_nxt;
return __prev_n;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename... _Args>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_emplace(std::true_type, _Args&&... __args)
-> pair<iterator, bool>
{
// First build the node to get access to the hash code
__node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
const key_type& __k = this->_M_extract()(__node->_M_v());
__hash_code __code;
__try
{
__code = this->_M_hash_code(__k);
}
__catch(...)
{
this->_M_deallocate_node(__node);
__throw_exception_again;
}
size_type __bkt = _M_bucket_index(__k, __code);
if (__node_type* __p = _M_find_node(__bkt, __k, __code))
{
// There is already an equivalent node, no insertion
this->_M_deallocate_node(__node);
return std::make_pair(iterator(__p), false);
}
// Insert the node
return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
true);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename... _Args>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
-> iterator
{
// First build the node to get its hash code.
__node_type* __node =
this->_M_allocate_node(std::forward<_Args>(__args)...);
__hash_code __code;
__try
{
__code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
}
__catch(...)
{
this->_M_deallocate_node(__node);
__throw_exception_again;
}
return _M_insert_multi_node(__hint._M_cur, __code, __node);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_insert_unique_node(size_type __bkt, __hash_code __code,
__node_type* __node, size_type __n_elt)
-> iterator
{
const __rehash_state& __saved_state = _M_rehash_policy._M_state();
std::pair<bool, std::size_t> __do_rehash
= _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count,
__n_elt);
__try
{
if (__do_rehash.first)
{
_M_rehash(__do_rehash.second, __saved_state);
__bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
}
this->_M_store_code(__node, __code);
// Always insert at the beginning of the bucket.
_M_insert_bucket_begin(__bkt, __node);
++_M_element_count;
return iterator(__node);
}
__catch(...)
{
this->_M_deallocate_node(__node);
__throw_exception_again;
}
}
// Insert node, in bucket bkt if no rehash (assumes no element with its key
// already present). Take ownership of the node, deallocate it on exception.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_insert_multi_node(__node_type* __hint, __hash_code __code,
__node_type* __node)
-> iterator
{
const __rehash_state& __saved_state = _M_rehash_policy._M_state();
std::pair<bool, std::size_t> __do_rehash
= _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
__try
{
if (__do_rehash.first)
_M_rehash(__do_rehash.second, __saved_state);
this->_M_store_code(__node, __code);
const key_type& __k = this->_M_extract()(__node->_M_v());
size_type __bkt = _M_bucket_index(__k, __code);
// Find the node before an equivalent one or use hint if it exists and
// if it is equivalent.
__node_base* __prev
= __builtin_expect(__hint != nullptr, false)
&& this->_M_equals(__k, __code, __hint)
? __hint
: _M_find_before_node(__bkt, __k, __code);
if (__prev)
{
// Insert after the node before the equivalent one.
__node->_M_nxt = __prev->_M_nxt;
__prev->_M_nxt = __node;
if (__builtin_expect(__prev == __hint, false))
// hint might be the last bucket node, in this case we need to
// update next bucket.
if (__node->_M_nxt
&& !this->_M_equals(__k, __code, __node->_M_next()))
{
size_type __next_bkt = _M_bucket_index(__node->_M_next());
if (__next_bkt != __bkt)
_M_buckets[__next_bkt] = __node;
}
}
else
// The inserted node has no equivalent in the
// hashtable. We must insert the new node at the
// beginning of the bucket to preserve equivalent
// elements' relative positions.
_M_insert_bucket_begin(__bkt, __node);
++_M_element_count;
return iterator(__node);
}
__catch(...)
{
this->_M_deallocate_node(__node);
__throw_exception_again;
}
}
// Insert v if no element with its key is already present.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename _Arg, typename _NodeGenerator>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, true_type,
size_type __n_elt)
-> pair<iterator, bool>
{
const key_type& __k = this->_M_extract()(__v);
__hash_code __code = this->_M_hash_code(__k);
size_type __bkt = _M_bucket_index(__k, __code);
__node_type* __n = _M_find_node(__bkt, __k, __code);
if (__n)
return std::make_pair(iterator(__n), false);
__n = __node_gen(std::forward<_Arg>(__v));
return { _M_insert_unique_node(__bkt, __code, __n, __n_elt), true };
}
// Insert v unconditionally.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
template<typename _Arg, typename _NodeGenerator>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_insert(const_iterator __hint, _Arg&& __v,
const _NodeGenerator& __node_gen, false_type)
-> iterator
{
// First compute the hash code so that we don't do anything if it
// throws.
__hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
// Second allocate new node so that we don't rehash if it throws.
__node_type* __node = __node_gen(std::forward<_Arg>(__v));
return _M_insert_multi_node(__hint._M_cur, __code, __node);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
erase(const_iterator __it)
-> iterator
{
__node_type* __n = __it._M_cur;
std::size_t __bkt = _M_bucket_index(__n);
// Look for previous node to unlink it from the erased one, this
// is why we need buckets to contain the before begin to make
// this search fast.
__node_base* __prev_n = _M_get_previous_node(__bkt, __n);
return _M_erase(__bkt, __prev_n, __n);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
-> iterator
{
if (__prev_n == _M_buckets[__bkt])
_M_remove_bucket_begin(__bkt, __n->_M_next(),
__n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
else if (__n->_M_nxt)
{
size_type __next_bkt = _M_bucket_index(__n->_M_next());
if (__next_bkt != __bkt)
_M_buckets[__next_bkt] = __prev_n;
}
__prev_n->_M_nxt = __n->_M_nxt;
iterator __result(__n->_M_next());
this->_M_deallocate_node(__n);
--_M_element_count;
return __result;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_erase(std::true_type, const key_type& __k)
-> size_type
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __bkt = _M_bucket_index(__k, __code);
// Look for the node before the first matching node.
__node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
if (!__prev_n)
return 0;
// We found a matching node, erase it.
__node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
_M_erase(__bkt, __prev_n, __n);
return 1;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_erase(std::false_type, const key_type& __k)
-> size_type
{
__hash_code __code = this->_M_hash_code(__k);
std::size_t __bkt = _M_bucket_index(__k, __code);
// Look for the node before the first matching node.
__node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
if (!__prev_n)
return 0;
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 526. Is it undefined if a function in the standard changes
// in parameters?
// We use one loop to find all matching nodes and another to deallocate
// them so that the key stays valid during the first loop. It might be
// invalidated indirectly when destroying nodes.
__node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
__node_type* __n_last = __n;
std::size_t __n_last_bkt = __bkt;
do
{
__n_last = __n_last->_M_next();
if (!__n_last)
break;
__n_last_bkt = _M_bucket_index(__n_last);
}
while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
// Deallocate nodes.
size_type __result = 0;
do
{
__node_type* __p = __n->_M_next();
this->_M_deallocate_node(__n);
__n = __p;
++__result;
--_M_element_count;
}
while (__n != __n_last);
if (__prev_n == _M_buckets[__bkt])
_M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
else if (__n_last && __n_last_bkt != __bkt)
_M_buckets[__n_last_bkt] = __prev_n;
__prev_n->_M_nxt = __n_last;
return __result;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
auto
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
erase(const_iterator __first, const_iterator __last)
-> iterator
{
__node_type* __n = __first._M_cur;
__node_type* __last_n = __last._M_cur;
if (__n == __last_n)
return iterator(__n);
std::size_t __bkt = _M_bucket_index(__n);
__node_base* __prev_n = _M_get_previous_node(__bkt, __n);
bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
std::size_t __n_bkt = __bkt;
for (;;)
{
do
{
__node_type* __tmp = __n;
__n = __n->_M_next();
this->_M_deallocate_node(__tmp);
--_M_element_count;
if (!__n)
break;
__n_bkt = _M_bucket_index(__n);
}
while (__n != __last_n && __n_bkt == __bkt);
if (__is_bucket_begin)
_M_remove_bucket_begin(__bkt, __n, __n_bkt);
if (__n == __last_n)
break;
__is_bucket_begin = true;
__bkt = __n_bkt;
}
if (__n && (__n_bkt != __bkt || __is_bucket_begin))
_M_buckets[__n_bkt] = __prev_n;
__prev_n->_M_nxt = __n;
return iterator(__n);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
clear() noexcept
{
this->_M_deallocate_nodes(_M_begin());
__builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
_M_element_count = 0;
_M_before_begin._M_nxt = nullptr;
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
rehash(size_type __n)
{
const __rehash_state& __saved_state = _M_rehash_policy._M_state();
std::size_t __buckets
= std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
__n);
__buckets = _M_rehash_policy._M_next_bkt(__buckets);
if (__buckets != _M_bucket_count)
_M_rehash(__buckets, __saved_state);
else
// No rehash, restore previous state to keep it consistent with
// container state.
_M_rehash_policy._M_reset(__saved_state);
}
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_rehash(size_type __n, const __rehash_state& __state)
{
__try
{
_M_rehash_aux(__n, __unique_keys());
}
__catch(...)
{
// A failure here means that buckets allocation failed. We only
// have to restore hash policy previous state.
_M_rehash_policy._M_reset(__state);
__throw_exception_again;
}
}
// Rehash when there is no equivalent elements.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_rehash_aux(size_type __n, std::true_type)
{
__bucket_type* __new_buckets = _M_allocate_buckets(__n);
__node_type* __p = _M_begin();
_M_before_begin._M_nxt = nullptr;
std::size_t __bbegin_bkt = 0;
while (__p)
{
__node_type* __next = __p->_M_next();
std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
if (!__new_buckets[__bkt])
{
__p->_M_nxt = _M_before_begin._M_nxt;
_M_before_begin._M_nxt = __p;
__new_buckets[__bkt] = &_M_before_begin;
if (__p->_M_nxt)
__new_buckets[__bbegin_bkt] = __p;
__bbegin_bkt = __bkt;
}
else
{
__p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
__new_buckets[__bkt]->_M_nxt = __p;
}
__p = __next;
}
_M_deallocate_buckets();
_M_bucket_count = __n;
_M_buckets = __new_buckets;
}
// Rehash when there can be equivalent elements, preserve their relative
// order.
template<typename _Key, typename _Value,
typename _Alloc, typename _ExtractKey, typename _Equal,
typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
typename _Traits>
void
_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_rehash_aux(size_type __n, std::false_type)
{
__bucket_type* __new_buckets = _M_allocate_buckets(__n);
__node_type* __p = _M_begin();
_M_before_begin._M_nxt = nullptr;
std::size_t __bbegin_bkt = 0;
std::size_t __prev_bkt = 0;
__node_type* __prev_p = nullptr;
bool __check_bucket = false;
while (__p)
{
__node_type* __next = __p->_M_next();
std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
if (__prev_p && __prev_bkt == __bkt)
{
// Previous insert was already in this bucket, we insert after
// the previously inserted one to preserve equivalent elements
// relative order.
__p->_M_nxt = __prev_p->_M_nxt;
__prev_p->_M_nxt = __p;
// Inserting after a node in a bucket require to check that we
// haven't change the bucket last node, in this case next
// bucket containing its before begin node must be updated. We
// schedule a check as soon as we move out of the sequence of
// equivalent nodes to limit the number of checks.
__check_bucket = true;
}
else
{
if (__check_bucket)
{
// Check if we shall update the next bucket because of
// insertions into __prev_bkt bucket.
if (__prev_p->_M_nxt)
{
std::size_t __next_bkt
= __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
__n);
if (__next_bkt != __prev_bkt)
__new_buckets[__next_bkt] = __prev_p;
}
__check_bucket = false;
}
if (!__new_buckets[__bkt])
{
__p->_M_nxt = _M_before_begin._M_nxt;
_M_before_begin._M_nxt = __p;
__new_buckets[__bkt] = &_M_before_begin;
if (__p->_M_nxt)
__new_buckets[__bbegin_bkt] = __p;
__bbegin_bkt = __bkt;
}
else
{
__p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
__new_buckets[__bkt]->_M_nxt = __p;
}
}
__prev_p = __p;
__prev_bkt = __bkt;
__p = __next;
}
if (__check_bucket && __prev_p->_M_nxt)
{
std::size_t __next_bkt
= __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
if (__next_bkt != __prev_bkt)
__new_buckets[__next_bkt] = __prev_p;
}
_M_deallocate_buckets();
_M_bucket_count = __n;
_M_buckets = __new_buckets;
}
#if __cplusplus > 201402L
template<typename, typename, typename> class _Hash_merge_helper { };
#endif // C++17
#if __cpp_deduction_guides >= 201606
// Used to constrain deduction guides
template<typename _Hash>
using _RequireNotAllocatorOrIntegral
= __enable_if_t<!__or_<is_integral<_Hash>, __is_allocator<_Hash>>::value>;
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // _HASHTABLE_H
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