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Construct an element in-place.
template< class Arg> std::pair< iterator, bool > emplace( string_view key, Arg&& arg);
Inserts a new element into the container constructed in-place with the
given argument if there is no element with the key
in the container. If the insertion occurs and results in a rehashing of
the container, all iterators and references are invalidated. Otherwise,
they are not affected. Rehashing occurs only if the new number of elements
is greater than capacity().
Amortized constant on average, worst case linear in size().
Strong guarantee. Calls to memory_resource::allocate
may throw.
A std::pair where first
is an iterator to the existing or inserted element, and second
is true if the insertion took
place or false otherwise.
|
Name |
Description |
|---|---|
|
|
The key used for lookup and insertion |
|
|
The argument used to construct the value. This will be passed
as |
|
Type |
Thrown On |
|---|---|
boost::system::system_error |
if key is too long. |