# Concurrently unsafe modifiers¶

All member functions in this section can only be performed serially. The behavior is undefined in case of concurrent execution of these member functions with other (either concurrently safe) methods.

## Clearing¶

void clear();


Removes all elements from the container.

## Erasing elements¶

iterator unsafe_erase( const_iterator pos );

iterator unsafe_erase( iterator pos );


Removes the element pointed to by pos from the container.

Invalidates all iterators and references to the removed element.

Returns: iterator that follows the removed element.

Requirements: the iterator pos should be valid, dereferenceable and point to the element in *this.

size_type unsafe_erase( const key_type& key );


Removes the element equivalent to key if it exists in the container.

Invalidates all iterators and references to the removed element.

Returns: the number of removed elements.

template <typename K>
size_type unsafe_erase( const K& key );


Removes the element that is equivalent to key if it exists in the container.

Invalidates all iterators and references to the removed element.

This overload only participates in overload resolution if all of the following conditions are met:

• The qualified-id hasher::transparent_key_equal is valid and denotes a type.

• std::is_convertible<K, iterator>::value is false.

• std::is_convertible<K, const_iterator>::value is false.

Returns: the number of removed elements.

## Erasing sequences¶

iterator unsafe_erase( const_iterator first, const_iterator last );


Removes all elements from the half-open interval [first, last) from the container.

Returns: iterator that follows the last removed element.

Requirements: the range [first, last) must be a valid subrange in *this.

## Extracting nodes¶

node_type unsafe_extract( iterator pos );

node_type unsafe_extract( const_iterator pos );


Transfers ownership of the element pointed to by pos from the container to the node handle.

No copy or move constructors of value_type are performed.

Invalidates all iterators to the extracted element. Pointers and references to the extracted element remain valid.

Returns: the node handle that owns the extracted element.

Requirements: the iterator pos should be valid, dereferenceable and point to the element in *this.

node_type unsafe_extract( const key_type& key );


If an element equivalent to key exists, transfers ownership of this element from the container to the node handle.

No copy or move constructors of value_type are performed.

If there are multiple elements equivalent to key, it is unspecified which element should be transferred.

Invalidates all iterators to the extracted element. Pointers and references to the extracted element remain valid.

Returns: the node handle that owns the extracted element or an empty node handle if an element equivalent to key was not found.

template <typename K>
node_type unsafe_extract( const K& key );


If an element equivalent to key exists, transfers ownership of this element from the container to the node handle.

No copy or move constructors of value_type are performed.

If there are multiple elements which are equivalent to key, it is unspecified which element should be transferred.

Invalidates all iterators to the extracted element. Pointers and references to the extracted element remain valid.

This overload only participates in overload resolution if all of the following conditions are met:

• The qualified-id hasher::transparent_key_equal is valid and denotes a type.

• std::is_convertible<K, iterator>::value is false.

• std::is_convertible<K, const_iterator>::value is false.

Returns: the node handle that owns the extracted element or an empty node handle if an element equivalent to key was not found.

## swap¶

void swap( concurrent_unordered_multiset& other ) noexcept(/*See below*/);


Swaps contents of *this and other.

Swaps allocators if std::allocator_traits<allocator_type>::propagate_on_container_swap::value is true.

Otherwise, if get_allocator() != other.get_allocator(), the behavior is undefined.

Exceptions: noexcept specification:

noexcept(std::allocator_traits<allocator_type>::is_always_equal::value &&
std::is_nothrow_swappable<hasher>::value &&
std::is_nothrow_swappable<key_equal>::value