...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Construct an element in-place.
template< class Arg>std::pair
<object::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. |