- Generated by
1.8.9.1
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libstdc++
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Public Types | |
| typedef _Alloc | allocator_type |
| using | const_iterator = typename __hashtable_base::const_iterator |
| using | const_local_iterator = typename __hashtable_base::const_local_iterator |
| typedef _Alloc::const_pointer | const_pointer |
| typedef _Alloc::const_reference | const_reference |
| using | difference_type = typename __hashtable_base::difference_type |
| using | iterator = typename __hashtable_base::iterator |
| typedef _Equal | key_equal |
| typedef _Key | key_type |
| using | local_iterator = typename __hashtable_base::local_iterator |
| typedef _Alloc::pointer | pointer |
| typedef _Alloc::reference | reference |
| using | size_type = typename __hashtable_base::size_type |
| typedef _Value | value_type |
Public Member Functions | |
| _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 &&) | |
| _Hashtable (size_type __n=10, const _H1 &__hf=_H1(), const key_equal &__eql=key_equal(), const allocator_type &__a=allocator_type()) | |
| 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 (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()) | |
| const _RehashPolicy & | __rehash_policy () const |
| void | __rehash_policy (const _RehashPolicy &) |
| template<typename... _Args> | |
| std::pair< typename _Hashtable< _Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits >::iterator, bool > | _M_emplace (std::true_type, _Args &&...__args) |
| template<typename _Arg > | |
| std::pair< typename _Hashtable< _Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits >::iterator, bool > | _M_insert (_Arg &&__v, std::true_type) |
| iterator | begin () noexcept |
| const_iterator | begin () const noexcept |
| local_iterator | begin (size_type __n) |
| const_local_iterator | begin (size_type __n) const |
| size_type | bucket (const key_type &__k) const |
| size_type | bucket_count () const noexcept |
| size_type | bucket_size (size_type __n) const |
| const_iterator | cbegin () const noexcept |
| const_local_iterator | cbegin (size_type __n) const |
| const_iterator | cend () const noexcept |
| const_local_iterator | cend (size_type __n) const |
| void | clear () noexcept |
| size_type | count (const key_type &__k) const |
| template<typename... _Args> | |
| __ireturn_type | emplace (_Args &&...__args) |
| template<typename... _Args> | |
| iterator | emplace_hint (const_iterator, _Args &&...__args) |
| bool | empty () const noexcept |
| iterator | end () noexcept |
| const_iterator | end () const noexcept |
| local_iterator | end (size_type __n) |
| const_local_iterator | end (size_type __n) const |
| std::pair< iterator, iterator > | equal_range (const key_type &__k) |
| std::pair< const_iterator, const_iterator > | equal_range (const key_type &__k) const |
| iterator | erase (const_iterator) |
| iterator | erase (iterator __it) |
| size_type | erase (const key_type &__k) |
| iterator | erase (const_iterator, const_iterator) |
| iterator | find (const key_type &__k) |
| const_iterator | find (const key_type &__k) const |
| allocator_type | get_allocator () const noexcept |
| key_equal | key_eq () const |
| float | load_factor () const noexcept |
| size_type | max_bucket_count () const noexcept |
| size_type | max_size () const noexcept |
| _Hashtable & | operator= (const _Hashtable &__ht) |
| _Hashtable & | operator= (_Hashtable &&__ht) |
| _Hashtable & | operator= (initializer_list< value_type > __l) |
| void | rehash (size_type __n) |
| size_type | size () const noexcept |
| void | swap (_Hashtable &) |
Protected Member Functions | |
| size_type | _M_bucket_index (__node_type *__n) const |
| size_type | _M_bucket_index (const key_type &__k, __hash_code __c) const |
| template<typename... _Args> | |
| std::pair< iterator, bool > | _M_emplace (std::true_type, _Args &&...__args) |
| template<typename... _Args> | |
| iterator | _M_emplace (std::false_type, _Args &&...__args) |
| const _Equal & | _M_eq () const |
| _Equal & | _M_eq () |
| bool | _M_equals (const _Key &__k, __hash_code __c, __node_type *__n) const |
| 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) |
| __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 * | _M_get_previous_node (size_type __bkt, __node_base *__n) |
| template<typename _Arg > | |
| std::pair< iterator, bool > | _M_insert (_Arg &&, std::true_type) |
| template<typename _Arg > | |
| iterator | _M_insert (_Arg &&, std::false_type) |
| void | _M_insert_bucket_begin (size_type, __node_type *) |
| iterator | _M_insert_multi_node (__hash_code __code, __node_type *__n) |
| iterator | _M_insert_unique_node (size_type __bkt, __hash_code __code, __node_type *__n) |
| void | _M_remove_bucket_begin (size_type __bkt, __node_type *__next_n, size_type __next_bkt) |
| void | _M_swap (_Hashtable_base &__x) |
Primary class template _Hashtable.
| _Value | CopyConstructible type. |
| _Key | CopyConstructible type. |
| _Alloc | An allocator type ([lib.allocator.requirements]) whose _Alloc::value_type is _Value. As a conforming extension, we allow for _Alloc::value_type != _Value. |
| _ExtractKey | Function object that takes an object of type _Value and returns a value of type _Key. |
| _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. |
| _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()]. |
| _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). |
| _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. |
| _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>) |
| _Traits | Compile-time class with three boolean std::integral_constant members: __cache_hash_code, __constant_iterators, __unique_keys. |
Each _Hashtable data structure has:
with _Bucket being _Hash_node* and _Hash_node containing:
In terms of Standard containers the hashtable is like the aggregation of:
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:
Definition at line 174 of file bits/hashtable.h.
1.8.9.1