[#absl-linked_hash_set]
= xref:absl.adoc[absl]::linked&lowbar;hash&lowbar;set
:relfileprefix: ../
:mrdocs:

A simple insertion&hyphen;ordered set&period;

== Synopsis

Declared in `&lt;absl&sol;container&sol;linked&lowbar;hash&lowbar;set&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template&lt;
    typename Key,
    typename KeyHash = absl::flat&lowbar;hash&lowbar;set&lt;Key&gt;::hasher,
    typename KeyEq = absl::flat&lowbar;hash&lowbar;set&lt;Key, KeyHash&gt;::key&lowbar;equal,
    typename Alloc = std::allocator&lt;Key&gt;&gt;
class linked&lowbar;hash&lowbar;set;
----

== Description

Provides O(1) amortized insertions and lookups, as well as iteration over the set in the insertion order&period; This class is thread&hyphen;compatible but NOT exception&hyphen;safe, and it supports heterogeneous lookups&period;

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:absl/linked_hash_set/allocator_type.adoc[`allocator&lowbar;type`] 
| The allocator type&period;
| xref:absl/linked_hash_set/const_iterator.adoc[`const&lowbar;iterator`] 
| The const iterator type, iterating in insertion order&period;
| xref:absl/linked_hash_set/const_pointer.adoc[`const&lowbar;pointer`] 
| A const pointer to an element&period;
| xref:absl/linked_hash_set/const_reference.adoc[`const&lowbar;reference`] 
| A const reference to an element&period;
| xref:absl/linked_hash_set/const_reverse_iterator.adoc[`const&lowbar;reverse&lowbar;iterator`] 
| The const reverse iterator type&period;
| xref:absl/linked_hash_set/difference_type.adoc[`difference&lowbar;type`] 
| The signed integer difference type&period;
| xref:absl/linked_hash_set/hasher.adoc[`hasher`] 
| The hash functor type&period;
| xref:absl/linked_hash_set/insert_return_type.adoc[`insert&lowbar;return&lowbar;type`] 
| The return type of node&hyphen;handle insertions&period;
| xref:absl/linked_hash_set/iterator.adoc[`iterator`] 
| The iterator type, iterating in insertion order&period;
| xref:absl/linked_hash_set/key_equal.adoc[`key&lowbar;equal`] 
| The key equality functor type&period;
| xref:absl/linked_hash_set/key_type.adoc[`key&lowbar;type`] 
| The key type of the set&period;
| xref:absl/linked_hash_set/node_type.adoc[`node&lowbar;type`] 
| The node handle type used to extract and reinsert elements&period;
| xref:absl/linked_hash_set/pointer.adoc[`pointer`] 
| A pointer to an element&period;
| xref:absl/linked_hash_set/reference.adoc[`reference`] 
| A reference to an element&period;
| xref:absl/linked_hash_set/reverse_iterator.adoc[`reverse&lowbar;iterator`] 
| The reverse iterator type&period;
| xref:absl/linked_hash_set/size_type.adoc[`size&lowbar;type`] 
| The unsigned integer size type&period;
| xref:absl/linked_hash_set/value_type.adoc[`value&lowbar;type`] 
| The value type stored in the set&period;
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/linked_hash_set/2constructor-0168.adoc[`linked&lowbar;hash&lowbar;set`]         [.small]#[constructor]#
| Constructors
| xref:absl/linked_hash_set/operator_assign-06.adoc[`operator&equals;`] 
| Assignment operators
| xref:absl/linked_hash_set/back-0f4.adoc[`back`] 
| `back` overloads
| xref:absl/linked_hash_set/begin-0c.adoc[`begin`] 
| `begin` overloads
| xref:absl/linked_hash_set/bucket_count.adoc[`bucket&lowbar;count`] 
| Returns the number of buckets in the underlying hash set&period;
| xref:absl/linked_hash_set/capacity.adoc[`capacity`] 
| Returns the number of elements the set can hold without rehashing&period;
| xref:absl/linked_hash_set/cbegin.adoc[`cbegin`] 
| Returns a const iterator to the first element, in insertion order&period;
| xref:absl/linked_hash_set/cend.adoc[`cend`] 
| Returns a const iterator past the last element&period;
| xref:absl/linked_hash_set/clear.adoc[`clear`] 
| Removes all elements from the set&period;
| xref:absl/linked_hash_set/contains.adoc[`contains`] 
| Returns whether the set contains an element with the given key&period;
| xref:absl/linked_hash_set/count.adoc[`count`] 
| Returns the number of elements matching the given key&period;
| xref:absl/linked_hash_set/crbegin.adoc[`crbegin`] 
| Returns a const reverse iterator to the last element&period;
| xref:absl/linked_hash_set/crend.adoc[`crend`] 
| Returns a const reverse iterator past the first element&period;
| xref:absl/linked_hash_set/emplace.adoc[`emplace`] 
| Constructs an element in place in the set&period;
| xref:absl/linked_hash_set/emplace_hint.adoc[`emplace&lowbar;hint`] 
| Constructs an element in place in the set using a position hint&period;
| xref:absl/linked_hash_set/empty.adoc[`empty`] 
| Returns whether the set is empty&period;
| xref:absl/linked_hash_set/end-0c6.adoc[`end`] 
| `end` overloads
| xref:absl/linked_hash_set/equal_range-055.adoc[`equal&lowbar;range`] 
| Returns the range of elements matching the given key&period;
| xref:absl/linked_hash_set/erase-09.adoc[`erase`] 
| `erase` overloads
| xref:absl/linked_hash_set/extract-0ca.adoc[`extract`] 
| `extract` overloads
| xref:absl/linked_hash_set/find-0b.adoc[`find`] 
| Finds the element with the given key&period;
| xref:absl/linked_hash_set/front-06.adoc[`front`] 
| `front` overloads
| xref:absl/linked_hash_set/get_allocator.adoc[`get&lowbar;allocator`] 
| Returns the allocator&period;
| xref:absl/linked_hash_set/hash_function.adoc[`hash&lowbar;function`] 
| Returns the hash functor&period;
| xref:absl/linked_hash_set/insert-03e.adoc[`insert`] 
| `insert` overloads
| xref:absl/linked_hash_set/key_eq.adoc[`key&lowbar;eq`] 
| Returns the key equality functor&period;
| xref:absl/linked_hash_set/load_factor.adoc[`load&lowbar;factor`] 
| Returns the current load factor of the underlying hash set&period;
| xref:absl/linked_hash_set/max_size.adoc[`max&lowbar;size`] 
| Returns the maximum number of elements the set can hold&period;
| xref:absl/linked_hash_set/merge-03.adoc[`merge`] 
| Merges the elements of another set into this one&period;
| xref:absl/linked_hash_set/pop_back.adoc[`pop&lowbar;back`] 
| Removes the last element from the set&period;
| xref:absl/linked_hash_set/pop_front.adoc[`pop&lowbar;front`] 
| Removes the first element from the set&period;
| xref:absl/linked_hash_set/rbegin-0a.adoc[`rbegin`] 
| `rbegin` overloads
| xref:absl/linked_hash_set/rehash.adoc[`rehash`] 
| Rehashes the underlying hash set to hold at least `n` buckets&period;
| xref:absl/linked_hash_set/rend-01.adoc[`rend`] 
| `rend` overloads
| xref:absl/linked_hash_set/reserve.adoc[`reserve`] 
| Reserves space for at least `n` elements&period;
| xref:absl/linked_hash_set/size.adoc[`size`] 
| Returns the number of elements in the set&period;
| xref:absl/linked_hash_set/swap.adoc[`swap`] 
| Swaps the contents of this set with another&period;
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:absl/operator_not_eq-0563.adoc[absl::operator!&equals;]`
| Returns whether two sets contain different elements&period;
| `xref:absl/operator_eq-08e.adoc[absl::operator&equals;&equals;]`
| Returns whether two sets contain the same elements&period;
|===


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