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374 lines
7.8 KiB
Markdown
374 lines
7.8 KiB
Markdown
---
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title: "unordered_multimap"
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---
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{{< callout type="info">}}
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Header: `unordered_multimap.h`
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Similar to: `std::unordered_multimap`
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{{< /callout >}}
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A fixed capacity unordered map.
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Uses `std::less` as the default key comparison method.
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```cpp
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template <typename TKey,
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typename TValue,
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size_t MAX_SIZE,
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size_t MAX_BUCKETS = MAX_SIZE,
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typename THash = etl::hash<TKey>,
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typename TKeyEqual = etl::equal_to<TKey>>
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class unordered_multimap
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```
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Inherits from `iunordered_map<TKey, TValue, THash, TKeyEqual>`.
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`etl::iunordered_map` may be used as a size independent pointer or reference type for any `etl::unordered_multimap` instance.
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## Template deduction guides
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C++17 and above
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```cpp
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template <typename... TPairs>
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etl::unordered_multimap(TPairs...)
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```
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### Example
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```cpp
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etl::unordered_multimap data{ etl::pair{0, 1}, etl::pair{2, 3}, etl::pair{4, 5}, etl::pair{6, 7} };
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```
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Defines data as an unordered map of `int`/`int` pairs, of length 4, containing the supplied data.
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## Make template
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C++11 and above
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```cpp
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template <typename TKey,
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typename TValue,
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typename THash = etl::hash<TKey>,
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typename TKeyEqual = etl::equal_to<TKey>
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typename... TPairs>
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constexpr auto make_unordered_map(TValues&&... values)
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```
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### Example
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```cpp
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auto data = etl::make_unordered_map<int, int>(etl::pair{0, 1}, etl::pair{2, 3},
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etl::pair{4, 5}, etl::pair{6, 7});
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```
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## Member types
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```cpp
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value_type pair<const TKey, T>
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key_type The type of the key value
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mapped_type The type of the mapped value
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hasher The type used to hash the key
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key_equal The functor used to compare keys
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reference A reference to a value_type
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const_reference A reference to a const value_type
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pointer A pointer to a value_type
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const_pointer A pointer to a const value_type
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size_type The type used for size information
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iterator Random access iterator
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const_iterator Constant random access iterator
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local_iterator Iterator to a bucket
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local_const_iterator A const iterator to a bucket
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```
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## Constructor
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```cpp
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unordered_multimap()
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```
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**Description**
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Default constructor
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---
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```cpp
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unordered_multimap(const unordered_multimap& other)
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```
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**Description**
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Copy constructor
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---
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```cpp
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template <typename TIterator>
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unordered_multimap(TIterator begin, TIterator end)
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```
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**Description**
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Construct from a range
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## Element access
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```cpp
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mapped_type& at(key_parameter_t key)
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const mapped_type& at(key_parameter_t key) const
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```
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**Description**
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Returns a reference or const reference to the indexed element.
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Raises an `etl::unordered_map_out_of_range` if the key is not in the table.
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If assert or exceptions are not enabled then undefined behaviour occurs.
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---
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```cpp
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mapped_type& operator[](key_parameter_t key)
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```
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**Description**
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Returns a reference to the indexed element.
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If the key does not exist then one is created using the default constructor.
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If the map is full then emits an `etl::unordered_map_full`.
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If asserts or exceptions are not enabled then undefined behaviour occurs.
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---
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```cpp
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iterator find(key_parameter_t key);
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const_iterator find (key_parameter_t key) const
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```
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**Description**
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Searches the container for an element with a key equivalent to key and returns an iterator to it if found, otherwise it returns an iterator to `etl::unordered_multimap::end()`.
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---
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```cpp
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bool contains(const_key_reference key) const
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```
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**Description**
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Check if the map contains the key.
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---
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```cpp
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template <typename K, typename KE = TKeyEqual>
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bool contains(const K& key) const
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```
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**Description**
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Check if the map contains the key.
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Enabled if the comparator is transparent.
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---
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```cpp
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size_type count(key_parameter_t key) const
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```
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**Description**
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Count elements with a specific key.
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Searches the container for elements with a key equivalent to key and returns the number of matches
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---
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```cpp
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iterator lower_bound(key_parameter_t key)
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const_iterator lower_bound(key_parameter_t key) const
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```
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**Description**
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Returns an iterator pointing to the first element in the container whose key is not considered to go before key (i.e., either it is equivalent or goes after).
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---
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```cpp
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iterator upper_bound(key_parameter_t key)
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const_iterator upper_bound(key_parameter_t key) const
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```
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**Description**
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Returns an iterator pointing to the first element in the container whose key is considered to go after `key`.
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---
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```cpp
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pair<iterator, iterator> equal_range(key_parameter_t key)
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pair<const_iterator, const_iterator> equal_range(key_parameter_t key) const
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```
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**Description**
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Returns the bounds of a range that includes all the elements in the container which have a key equivalent to `key`.
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## Iterators
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```cpp
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iterator begin()
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const_iterator begin() const
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const_iterator cbegin() const
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```
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**Description**
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Returns an iterator to the beginning of the map.
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---
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```cpp
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iterator end()
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const_iterator end() const
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const_iterator cend() const
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```
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**Description**
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Returns an iterator to the end of the map.
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## Capacity
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```cpp
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bool empty() const
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```
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**Description**
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Returns `true` if the size of the map is zero, otherwise `false`.
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---
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```cpp
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bool full() const
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```
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**Description**
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Returns `true` if the size of the map is `SIZE`, otherwise `false`.
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---
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```cpp
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size_t size() const
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```
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**Description**
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Returns the size of the map.
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---
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```cpp
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size_t max_size() const
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```
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**Description**
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Returns the maximum possible size of the map.
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---
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```cpp
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size_t available() const
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```
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**Description**
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Returns the remaining available capacity in the map.
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---
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```cpp
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size_type get_bucket_index(key_parameter_t key) const
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```
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**Description**
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Returns the bucket index for the key.
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---
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```cpp
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size_type bucket_size(key_parameter_t key) const
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```
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**Description**
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Returns the size of the bucket key.
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---
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```cpp
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size_type max_bucket_count() const
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```
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**Description**
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Returns the maximum number of the buckets the container can hold.
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---
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```cpp
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float load_factor() const
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```
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**Description**
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Returns the load factor = size / bucket_count
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---
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```cpp
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hasher hash_function() const
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```
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**Description**
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Returns the function that hashes the keys.
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---
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```cpp
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key_equal key_eq() const
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```
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**Description**
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Returns the function that compares the keys.
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## Modifiers
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```cpp
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template <typename TIterator>
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void assign(TIterator first, TIterator last)
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```
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**Description**
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Assigns elements from the range [`first`, `last`)].
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Clears the container before assigning.
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---
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```cpp
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pair<iterator, bool> insert(const value_type& key_value_pair)
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iterator insert(const_iterator, const value_type& key_value_pair)
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```
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**Description**
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Assigns elements from the range [`first`, `last`)].
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Clears the container before assigning.
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---
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```cpp
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template <template TIterator>
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void insert(TIterator first, TIterator last)
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```
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**Description**
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Inserts the range [`first`, `last`)] into the map.
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If the map is full then emits an `etl::unordered_map_full error`.
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If asserts or exceptions are not enabled then undefined behaviour occurs.
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---
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```cpp
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size_t erase(key_parameter_t key)
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```
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**Description**
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Removes the element with the key `key`.
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---
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```cpp
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iterator erase(const_iterator ielement)
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```
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**Description**
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Removes the element with the key `key`.
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---
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```cpp
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iterator erase(const_iterator first, const_iterator last)
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```
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**Description**
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Erases values in the map.
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Iterator are not checked for validity.
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---
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```cpp
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void clear()
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```
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**Description**
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Clears the map to a size of zero.
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## Non-member functions
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```cpp
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operator ==
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```
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**Description**
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`true` if the contents of the maps are equal, otherwise `false`.
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---
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```cpp
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operator !=
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```
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**Description**
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`true` if the contents of the maps are not equal, otherwise `false`.
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