Insert a constructed element in-place.
template< class Arg> iterator emplace( const_iterator pos, Arg&& arg);
Inserts a new element into the container directly before
pos. The element is constructed using
placement-new with the parameter
capacity() < size() + 1, a reallocation
occurs first, and all iterators and references are invalidated. Otherwise,
only the iterators and references from the insertion point forward are
invalidated. All past-the-end iterators are also invalidated.
Constant plus linear in
Strong guarantee. Calls to
Iterator before which the element will be inserted. This may
The argument to forward to the
An iterator to the inserted element