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hashtable.h
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hashtable.h
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// hashtable.h header -*- C++ -*-
// Copyright (C) 2007-2024 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>
#include <bits/enable_special_members.h>
#include <bits/stl_algobase.h> // fill_n
#include <bits/stl_function.h> // __has_is_transparent_t
#if __cplusplus > 201402L
# include <bits/node_handle.h>
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/// @cond undocumented
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&>>>;
// Helper to conditionally delete the default constructor.
// The _Hash_node_base type is used to distinguish this specialization
// from any other potentially-overlapping subobjects of the hashtable.
template<typename _Equal, typename _Hash, typename _Allocator>
using _Hashtable_enable_default_ctor
= _Enable_default_constructor<__and_<is_default_constructible<_Equal>,
is_default_constructible<_Hash>,
is_default_constructible<_Allocator>>{},
__detail::_Hash_node_base>;
/**
* 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 _Hash 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 _RangeHash 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 _Unused Not used.
*
* @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 for n_ins insertions.
* 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_base* 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.
*
* Note that all equivalent values, if any, are next to each other, if
* we find a non-equivalent value after an equivalent one it means that
* we won't find any new equivalent value.
*
* 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 _Hash, typename _RangeHash, typename _Unused,
typename _RehashPolicy, typename _Traits>
class _Hashtable
: public __detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal,
_Hash, _RangeHash, _Unused, _Traits>,
public __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>,
public __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>,
public __detail::_Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>,
public __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
_Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>,
private __detail::_Hashtable_alloc<
__alloc_rebind<_Alloc,
__detail::_Hash_node<_Value,
_Traits::__hash_cached::value>>>,
private _Hashtable_enable_default_ctor<_Equal, _Hash, _Alloc>
{
static_assert(is_same<typename remove_cv<_Value>::type, _Value>::value,
"unordered container must have a non-const, non-volatile value_type");
#if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Value>{},
"unordered container must have the same value_type as its allocator");
#endif
static_assert(is_copy_constructible<_Hash>::value,
"hash function must be copy constructible");
using __traits_type = _Traits;
using __hash_cached = typename __traits_type::__hash_cached;
using __constant_iterators = typename __traits_type::__constant_iterators;
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 __node_value_type =
__detail::_Hash_node_value<_Value, __hash_cached::value>;
using __node_ptr = typename __hashtable_alloc::__node_ptr;
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 __node_base_ptr = typename __hashtable_alloc::__node_base_ptr;
using __buckets_ptr = typename __hashtable_alloc::__buckets_ptr;
using __insert_base = __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey,
_Equal, _Hash,
_RangeHash, _Unused,
_RehashPolicy, _Traits>;
using __enable_default_ctor
= _Hashtable_enable_default_ctor<_Equal, _Hash, _Alloc>;
using __rehash_guard_t
= __detail::_RehashStateGuard<_RehashPolicy>;
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;
using iterator = typename __insert_base::iterator;
using const_iterator = typename __insert_base::const_iterator;
using local_iterator = __detail::_Local_iterator<key_type, _Value,
_ExtractKey, _Hash, _RangeHash, _Unused,
__constant_iterators::value,
__hash_cached::value>;
using const_local_iterator = __detail::_Local_const_iterator<
key_type, _Value,
_ExtractKey, _Hash, _RangeHash, _Unused,
__constant_iterators::value, __hash_cached::value>;
private:
using __rehash_type = _RehashPolicy;
using __unique_keys = typename __traits_type::__unique_keys;
using __hashtable_base = __detail::
_Hashtable_base<_Key, _Value, _ExtractKey,
_Equal, _Hash, _RangeHash, _Unused, _Traits>;
using __hash_code_base = typename __hashtable_base::__hash_code_base;
using __hash_code = typename __hashtable_base::__hash_code;
using __ireturn_type = typename __insert_base::__ireturn_type;
using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
_Equal, _Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>;
using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
_ExtractKey, _Equal,
_Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>;
using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
_Equal, _Hash, _RangeHash, _Unused,
_RehashPolicy, _Traits>;
using __reuse_or_alloc_node_gen_t =
__detail::_ReuseOrAllocNode<__node_alloc_type>;
using __alloc_node_gen_t =
__detail::_AllocNode<__node_alloc_type>;
using __node_builder_t =
__detail::_NodeBuilder<_ExtractKey>;
// Simple RAII type for managing a node containing an element
struct _Scoped_node
{
// Take ownership of a node with a constructed element.
_Scoped_node(__node_ptr __n, __hashtable_alloc* __h)
: _M_h(__h), _M_node(__n) { }
// Allocate a node and construct an element within it.
template<typename... _Args>
_Scoped_node(__hashtable_alloc* __h, _Args&&... __args)
: _M_h(__h),
_M_node(__h->_M_allocate_node(std::forward<_Args>(__args)...))
{ }
// Destroy element and deallocate node.
~_Scoped_node() { if (_M_node) _M_h->_M_deallocate_node(_M_node); };
_Scoped_node(const _Scoped_node&) = delete;
_Scoped_node& operator=(const _Scoped_node&) = delete;
__hashtable_alloc* _M_h;
__node_ptr _M_node;
};
template<typename _Ht>
static constexpr
__conditional_t<std::is_lvalue_reference<_Ht>::value,
const value_type&, value_type&&>
__fwd_value_for(value_type& __val) noexcept
{ return std::move(__val); }
// 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; };
// To get bucket index we need _RangeHash not to throw.
static_assert(is_nothrow_default_constructible<_RangeHash>::value,
"Functor used to map hash code to bucket index"
" must be nothrow default constructible");
static_assert(noexcept(
std::declval<const _RangeHash&>()((std::size_t)0, (std::size_t)0)),
"Functor used to map hash code to bucket index must be"
" noexcept");
// To compute bucket index we also need _ExtratKey not to throw.
static_assert(is_nothrow_default_constructible<_ExtractKey>::value,
"_ExtractKey must be nothrow default constructible");
static_assert(noexcept(
std::declval<const _ExtractKey&>()(std::declval<_Value>())),
"_ExtractKey functor must be noexcept invocable");
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _Hasha, typename _RangeHasha, typename _Unuseda,
typename _RehashPolicya, typename _Traitsa,
bool _Unique_keysa>
friend struct __detail::_Map_base;
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _Hasha, typename _RangeHasha, typename _Unuseda,
typename _RehashPolicya, typename _Traitsa>
friend struct __detail::_Insert_base;
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _Hasha, typename _RangeHasha, typename _Unuseda,
typename _RehashPolicya, typename _Traitsa,
bool _Constant_iteratorsa>
friend struct __detail::_Insert;
template<typename _Keya, typename _Valuea, typename _Alloca,
typename _ExtractKeya, typename _Equala,
typename _Hasha, typename _RangeHasha, typename _Unuseda,
typename _RehashPolicya, typename _Traitsa,
bool _Unique_keysa>
friend struct __detail::_Equality;
public:
using size_type = typename __hashtable_base::size_type;
using difference_type = typename __hashtable_base::difference_type;
#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:
__buckets_ptr _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 bucket
// 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.
__node_base_ptr _M_single_bucket = nullptr;
void
_M_update_bbegin()
{
if (auto __begin = _M_begin())
_M_buckets[_M_bucket_index(*__begin)] = &_M_before_begin;
}
void
_M_update_bbegin(__node_ptr __n)
{
_M_before_begin._M_nxt = __n;
_M_update_bbegin();
}
bool
_M_uses_single_bucket(__buckets_ptr __bkts) const
{ return __builtin_expect(__bkts == &_M_single_bucket, false); }
bool
_M_uses_single_bucket() const
{ return _M_uses_single_bucket(_M_buckets); }
static constexpr size_t
__small_size_threshold() noexcept
{
return
__detail::_Hashtable_hash_traits<_Hash>::__small_size_threshold();
}
__hashtable_alloc&
_M_base_alloc() { return *this; }
__buckets_ptr
_M_allocate_buckets(size_type __bkt_count)
{
if (__builtin_expect(__bkt_count == 1, false))
{
_M_single_bucket = nullptr;
return &_M_single_bucket;
}
return __hashtable_alloc::_M_allocate_buckets(__bkt_count);
}
void
_M_deallocate_buckets(__buckets_ptr __bkts, size_type __bkt_count)
{
if (_M_uses_single_bucket(__bkts))
return;
__hashtable_alloc::_M_deallocate_buckets(__bkts, __bkt_count);
}
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_ptr
_M_bucket_begin(size_type __bkt) const
{
__node_base_ptr __n = _M_buckets[__bkt];
return __n ? static_cast<__node_ptr>(__n->_M_nxt) : nullptr;
}
__node_ptr
_M_begin() const
{ return static_cast<__node_ptr>(_M_before_begin._M_nxt); }
// Assign *this using another _Hashtable instance. Whether elements
// are copied or moved depends on the _Ht reference.
template<typename _Ht>
void
_M_assign_elements(_Ht&&);
template<typename _Ht, typename _NodeGenerator>
void
_M_assign(_Ht&&, const _NodeGenerator&);
void
_M_move_assign(_Hashtable&&, true_type);
void
_M_move_assign(_Hashtable&&, false_type);
void
_M_reset() noexcept;
_Hashtable(const _Hash& __h, const _Equal& __eq,
const allocator_type& __a)
: __hashtable_base(__h, __eq),
__hashtable_alloc(__node_alloc_type(__a)),
__enable_default_ctor(_Enable_default_constructor_tag{})
{ }
template<bool _No_realloc = true>
static constexpr bool
_S_nothrow_move()
{
#if __cplusplus <= 201402L
return __and_<__bool_constant<_No_realloc>,
is_nothrow_copy_constructible<_Hash>,
is_nothrow_copy_constructible<_Equal>>::value;
#else
if constexpr (_No_realloc)
if constexpr (is_nothrow_copy_constructible<_Hash>())
return is_nothrow_copy_constructible<_Equal>();
return false;
#endif
}
_Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
true_type /* alloc always equal */)
noexcept(_S_nothrow_move());
_Hashtable(_Hashtable&&, __node_alloc_type&&,
false_type /* alloc always equal */);
template<typename _InputIterator>
_Hashtable(_InputIterator __first, _InputIterator __last,
size_type __bkt_count_hint,
const _Hash&, const _Equal&, const allocator_type&,
true_type __uks);
template<typename _InputIterator>
_Hashtable(_InputIterator __first, _InputIterator __last,
size_type __bkt_count_hint,
const _Hash&, const _Equal&, const allocator_type&,
false_type __uks);
public:
// Constructor, destructor, assignment, swap
_Hashtable() = default;
_Hashtable(const _Hashtable&);
_Hashtable(const _Hashtable&, const allocator_type&);
explicit
_Hashtable(size_type __bkt_count_hint,
const _Hash& __hf = _Hash(),
const key_equal& __eql = key_equal(),
const allocator_type& __a = allocator_type());
// Use delegating constructors.
_Hashtable(_Hashtable&& __ht)
noexcept(_S_nothrow_move())
: _Hashtable(std::move(__ht), std::move(__ht._M_node_allocator()),
true_type{})
{ }
_Hashtable(_Hashtable&& __ht, const allocator_type& __a)
noexcept(_S_nothrow_move<__node_alloc_traits::_S_always_equal()>())
: _Hashtable(std::move(__ht), __node_alloc_type(__a),
typename __node_alloc_traits::is_always_equal{})
{ }
explicit
_Hashtable(const allocator_type& __a)
: __hashtable_alloc(__node_alloc_type(__a)),
__enable_default_ctor(_Enable_default_constructor_tag{})
{ }
template<typename _InputIterator>
_Hashtable(_InputIterator __f, _InputIterator __l,
size_type __bkt_count_hint = 0,
const _Hash& __hf = _Hash(),
const key_equal& __eql = key_equal(),
const allocator_type& __a = allocator_type())
: _Hashtable(__f, __l, __bkt_count_hint, __hf, __eql, __a,
__unique_keys{})
{ }
_Hashtable(initializer_list<value_type> __l,
size_type __bkt_count_hint = 0,
const _Hash& __hf = _Hash(),
const key_equal& __eql = key_equal(),
const allocator_type& __a = allocator_type())
: _Hashtable(__l.begin(), __l.end(), __bkt_count_hint,
__hf, __eql, __a, __unique_keys{})
{ }
_Hashtable&
operator=(const _Hashtable& __ht);
_Hashtable&
operator=(_Hashtable&& __ht)
noexcept(__node_alloc_traits::_S_nothrow_move()
&& is_nothrow_move_assignable<_Hash>::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_gen_t __roan(_M_begin(), *this);
_M_before_begin._M_nxt = nullptr;
clear();
// We consider that all elements of __l are going to be inserted.
auto __l_bkt_count = _M_rehash_policy._M_bkt_for_elements(__l.size());
// Do not shrink to keep potential user reservation.
if (_M_bucket_count < __l_bkt_count)
rehash(__l_bkt_count);
this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys{});
return *this;
}
~_Hashtable() noexcept;
void
swap(_Hashtable&)
noexcept(__and_<__is_nothrow_swappable<_Hash>,
__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 __bkt) const
{ return std::distance(begin(__bkt), end(__bkt)); }
size_type
bucket(const key_type& __k) const
{ return _M_bucket_index(this->_M_hash_code(__k)); }
local_iterator
begin(size_type __bkt)
{
return local_iterator(*this, _M_bucket_begin(__bkt),
__bkt, _M_bucket_count);
}
local_iterator
end(size_type __bkt)
{ return local_iterator(*this, nullptr, __bkt, _M_bucket_count); }
const_local_iterator
begin(size_type __bkt) const
{
return const_local_iterator(*this, _M_bucket_begin(__bkt),
__bkt, _M_bucket_count);
}
const_local_iterator
end(size_type __bkt) const
{ return const_local_iterator(*this, nullptr, __bkt, _M_bucket_count); }
// DR 691.
const_local_iterator
cbegin(size_type __bkt) const
{
return const_local_iterator(*this, _M_bucket_begin(__bkt),
__bkt, _M_bucket_count);
}
const_local_iterator
cend(size_type __bkt) const
{ return const_local_iterator(*this, nullptr, __bkt, _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;
#ifdef __glibcxx_generic_unordered_lookup // C++ >= 20 && HOSTED
template<typename _Kt,
typename = __has_is_transparent_t<_Hash, _Kt>,
typename = __has_is_transparent_t<_Equal, _Kt>>
iterator
_M_find_tr(const _Kt& __k);
template<typename _Kt,
typename = __has_is_transparent_t<_Hash, _Kt>,
typename = __has_is_transparent_t<_Equal, _Kt>>
const_iterator
_M_find_tr(const _Kt& __k) const;
template<typename _Kt,
typename = __has_is_transparent_t<_Hash, _Kt>,
typename = __has_is_transparent_t<_Equal, _Kt>>
size_type
_M_count_tr(const _Kt& __k) const;
template<typename _Kt,
typename = __has_is_transparent_t<_Hash, _Kt>,
typename = __has_is_transparent_t<_Equal, _Kt>>
pair<iterator, iterator>
_M_equal_range_tr(const _Kt& __k);
template<typename _Kt,
typename = __has_is_transparent_t<_Hash, _Kt>,
typename = __has_is_transparent_t<_Equal, _Kt>>
pair<const_iterator, const_iterator>
_M_equal_range_tr(const _Kt& __k) const;
#endif // __glibcxx_generic_unordered_lookup
private:
// Bucket index computation helpers.
size_type
_M_bucket_index(const __node_value_type& __n) const noexcept
{ return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
size_type
_M_bucket_index(__hash_code __c) const
{ return __hash_code_base::_M_bucket_index(__c, _M_bucket_count); }
__node_base_ptr
_M_find_before_node(const key_type&);
// Find and insert helper functions and types
// Find the node before the one matching the criteria.
__node_base_ptr
_M_find_before_node(size_type, const key_type&, __hash_code) const;
template<typename _Kt>
__node_base_ptr
_M_find_before_node_tr(size_type, const _Kt&, __hash_code) const;
__node_ptr
_M_find_node(size_type __bkt, const key_type& __key,
__hash_code __c) const
{
__node_base_ptr __before_n = _M_find_before_node(__bkt, __key, __c);
if (__before_n)
return static_cast<__node_ptr>(__before_n->_M_nxt);
return nullptr;
}
template<typename _Kt>
__node_ptr
_M_find_node_tr(size_type __bkt, const _Kt& __key,
__hash_code __c) const
{
auto __before_n = _M_find_before_node_tr(__bkt, __key, __c);
if (__before_n)
return static_cast<__node_ptr>(__before_n->_M_nxt);
return nullptr;
}
// Insert a node at the beginning of a bucket.
void
_M_insert_bucket_begin(size_type __bkt, __node_ptr __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;
}
}
// Remove the bucket first node
void
_M_remove_bucket_begin(size_type __bkt, __node_ptr __next_n,
size_type __next_bkt)
{
if (!__next_n)
_M_buckets[__bkt] = nullptr;
else if (__next_bkt != __bkt)
{
_M_buckets[__next_bkt] = _M_buckets[__bkt];
_M_buckets[__bkt] = nullptr;
}
}
// Get the node before __n in the bucket __bkt
__node_base_ptr
_M_get_previous_node(size_type __bkt, __node_ptr __n);
pair<__node_ptr, __hash_code>
_M_compute_hash_code(__node_ptr __hint, const key_type& __k) const;
// Insert node __n with hash code __code, in bucket __bkt if no
// rehash (assumes no element with same key already present).
// Takes ownership of __n if insertion succeeds, throws otherwise.
iterator
_M_insert_unique_node(size_type __bkt, __hash_code,
__node_ptr __n, size_type __n_elt = 1);
// Insert node __n with key __k and hash code __code.
// Takes ownership of __n if insertion succeeds, throws otherwise.
iterator
_M_insert_multi_node(__node_ptr __hint,
__hash_code __code, __node_ptr __n);
template<typename... _Args>
std::pair<iterator, bool>
_M_emplace(true_type __uks, _Args&&... __args);
template<typename... _Args>
iterator
_M_emplace(false_type __uks, _Args&&... __args)
{ return _M_emplace(cend(), __uks, std::forward<_Args>(__args)...); }
// Emplace with hint, useless when keys are unique.
template<typename... _Args>
iterator
_M_emplace(const_iterator, true_type __uks, _Args&&... __args)
{ return _M_emplace(__uks, std::forward<_Args>(__args)...).first; }
template<typename... _Args>
iterator
_M_emplace(const_iterator, false_type __uks, _Args&&... __args);
template<typename _Kt, typename _Arg, typename _NodeGenerator>
std::pair<iterator, bool>
_M_insert_unique(_Kt&&, _Arg&&, const _NodeGenerator&);
template<typename _Kt>
static __conditional_t<
__and_<__is_nothrow_invocable<_Hash&, const key_type&>,
__not_<__is_nothrow_invocable<_Hash&, _Kt>>>::value,
key_type, _Kt&&>
_S_forward_key(_Kt&& __k)
{ return std::forward<_Kt>(__k); }
static const key_type&
_S_forward_key(const key_type& __k)
{ return __k; }
static key_type&&
_S_forward_key(key_type&& __k)
{ return std::move(__k); }
template<typename _Arg, typename _NodeGenerator>
std::pair<iterator, bool>
_M_insert_unique_aux(_Arg&& __arg, const _NodeGenerator& __node_gen)
{
return _M_insert_unique(
_S_forward_key(_ExtractKey{}(std::forward<_Arg>(__arg))),
std::forward<_Arg>(__arg), __node_gen);
}
template<typename _Arg, typename _NodeGenerator>
std::pair<iterator, bool>
_M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
true_type /* __uks */)
{
using __to_value
= __detail::_ConvertToValueType<_ExtractKey, value_type>;
return _M_insert_unique_aux(
__to_value{}(std::forward<_Arg>(__arg)), __node_gen);
}
template<typename _Arg, typename _NodeGenerator>
iterator
_M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
false_type __uks)
{
using __to_value
= __detail::_ConvertToValueType<_ExtractKey, value_type>;
return _M_insert(cend(),
__to_value{}(std::forward<_Arg>(__arg)), __node_gen, __uks);
}
// 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 __uks)
{
return
_M_insert(std::forward<_Arg>(__arg), __node_gen, __uks).first;
}
// Insert with hint when keys are not unique.
template<typename _Arg, typename _NodeGenerator>
iterator
_M_insert(const_iterator, _Arg&&,
const _NodeGenerator&, false_type __uks);
size_type
_M_erase(true_type __uks, const key_type&);
size_type
_M_erase(false_type __uks, const key_type&);
iterator
_M_erase(size_type __bkt, __node_base_ptr __prev_n, __node_ptr __n);
public:
// Emplace