[#bsl-hash_map]
= xref:bsl.adoc[bsl]::hash_map
:relfileprefix: ../
:mrdocs:

Legacy STLPort hash container mapping unique keys to values.

== Synopsis

Declared in `<bslstp_hashmap.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class _Key,
    class _Tp,
    class _HashFcn = BloombergLP::bslstp::HashSelector<_Key>::Type,
    class _EqualKey = bsl::ComparatorSelector<_Key>::Type,
    class _Alloc = xref:bsl/allocator-0df.adoc[bsl::allocator<pair<_Key const, _Tp>>]>
class hash_map;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/hash_map/_value_type.adoc[`_value_type`] 
| Internal synonym for the element `pair` type.
| xref:bsl/hash_map/allocator_type.adoc[`allocator_type`] 
| Allocator type used by this map.
| xref:bsl/hash_map/const_iterator.adoc[`const_iterator`] 
| Iterator providing non‐modifiable access to elements.
| xref:bsl/hash_map/const_pointer.adoc[`const_pointer`] 
| Pointer to a non‐modifiable element.
| xref:bsl/hash_map/const_reference.adoc[`const_reference`] 
| Reference to a non‐modifiable element.
| xref:bsl/hash_map/data_type.adoc[`data_type`] 
| Mapped value type (synonym for `mapped_type`).
| xref:bsl/hash_map/difference_type.adoc[`difference_type`] 
| Signed integral type used for iterator distances.
| xref:bsl/hash_map/hasher.adoc[`hasher`] 
| Hash functor type.
| xref:bsl/hash_map/iterator.adoc[`iterator`] 
| Iterator providing modifiable access to elements.
| xref:bsl/hash_map/key_equal.adoc[`key_equal`] 
| Key‐equality functor type.
| xref:bsl/hash_map/key_type.adoc[`key_type`] 
| Key type used by this container.
| xref:bsl/hash_map/mapped_type.adoc[`mapped_type`] 
| Type of the mapped value associated with each key.
| xref:bsl/hash_map/pointer.adoc[`pointer`] 
| Pointer to a modifiable element.
| xref:bsl/hash_map/reference.adoc[`reference`] 
| Reference to a modifiable element.
| xref:bsl/hash_map/size_type.adoc[`size_type`] 
| Unsigned integral type used for sizes.
| xref:bsl/hash_map/value_type.adoc[`value_type`] 
| Element type stored in the map (`pair<const key, mapped>`).
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/hash_map/2constructor-0e5.adoc[`hash_map`]         [.small]#[constructor]#
| Constructors
| xref:bsl/hash_map/begin-04.adoc[`begin`] 
| `begin` overloads
| xref:bsl/hash_map/bucket_count.adoc[`bucket_count`] 
| Return the number of buckets in this container.
| xref:bsl/hash_map/clear.adoc[`clear`] 
| Remove all elements from this map.
| xref:bsl/hash_map/count.adoc[`count`] 
| Return the number of elements matching the specified key.
| xref:bsl/hash_map/elems_in_bucket.adoc[`elems_in_bucket`] 
| Return the number of elements in the specified bucket.
| xref:bsl/hash_map/empty.adoc[`empty`] 
| Return `true` if this map contains no elements.
| xref:bsl/hash_map/end-02.adoc[`end`] 
| `end` overloads
| xref:bsl/hash_map/equal_range-0b3b.adoc[`equal_range`] 
| `equal_range` overloads
| xref:bsl/hash_map/erase-0a.adoc[`erase`] 
| `erase` overloads
| xref:bsl/hash_map/find-0c.adoc[`find`] 
| `find` overloads
| xref:bsl/hash_map/get_allocator.adoc[`get_allocator`] 
| Return the allocator used by this map.
| xref:bsl/hash_map/hash_funct.adoc[`hash_funct`] 
| Return the hash functor used by this map.
| xref:bsl/hash_map/insert-0c.adoc[`insert`] 
| `insert` overloads
| xref:bsl/hash_map/insert_noresize.adoc[`insert_noresize`] 
| Insert `__obj` without resizing the bucket vector if the key is new.
| xref:bsl/hash_map/key_eq.adoc[`key_eq`] 
| Return the key‐equality functor used by this map.
| xref:bsl/hash_map/max_bucket_count.adoc[`max_bucket_count`] 
| Return the maximum number of buckets this container can use.
| xref:bsl/hash_map/max_size.adoc[`max_size`] 
| Return an upper bound on the number of elements this map can hold.
| xref:bsl/hash_map/operator_subs.adoc[`operator[]`] 
| Return a reference to the mapped value for `__key`, inserting a default‐constructed value if the key is absent.
| xref:bsl/hash_map/resize.adoc[`resize`] 
| Rebuild the bucket vector using a size suggested by the specified hint.
| xref:bsl/hash_map/size.adoc[`size`] 
| Return the number of elements in this map.
| xref:bsl/hash_map/swap.adoc[`swap`] 
| Exchange the contents of this map with those of the specified map.
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/hash_map/_M_equal.adoc[`_M_equal`] 
| Return `true` if the specified maps contain the same elements.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/operator_not_eq-0f.adoc[`operator!=`]
| Return `true` if the specified hash maps do not contain the same elements.
| xref:bsl/operator_eq-08d.adoc[`operator==`]
| Return `true` if the specified hash maps contain the same elements.
| xref:bsl/swap-030.adoc[`swap`]
| Exchange the contents of the specified hash maps.
|===


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