Insert into this unordered set a newly created value_type object, constructed by forwarding get_allocator() (if required) and the specified (variable number of) arguments to the corresponding constructor of value_type, if a key equivalent to such a value does not already exist in this set; otherwise, this method has no effect (other than possibly creating a temporary value_type object). Return a pair whose first member is an iterator referring to the (possibly newly created and inserted) object in this set whose value is equivalent to that of an object constructed from arguments, and whose second member is true if a new value was inserted, and false if an equivalent key was already present. This method requires that the (template parameter) type KEY be emplace-constructible into this set from arguments (see {Requirements on KEY}).
Declared in <bslstl_unorderedset.h>
template<class... Args>
pair<iterator, bool>
emplace(Args&&... arguments);