BloombergLP::bslstl::HashTable::emplaceIfMissing

Insert into this hash-table a newly-created ValueType object, constructed by forwarding the specified (variable number of) arguments to the corresponding constructor of ValueType, if a key equivalent to that of the newly-created object does not already exist in this hash-table. Return the address of the (possibly newly created and inserted) element in this hash table whose key is equivalent to that of an object created from arguments. Load true into the specified isInsertedFlag if a new value was inserted, and false if an equivalent key was already present. If this hash-table contains more than one element with an equivalent key, return the first such element (from the contiguous sequence of elements having a matching key). Additional buckets are allocated, as needed, to preserve the invariant loadFactor <= maxLoadFactor. If this function tries to allocate a number of buckets larger than can be represented by this hash-table's SizeType, a std::length_error exception is thrown. This method requires that the ValueType defined in the (template parameter) type KEY_CONFIG be emplace-constructible into this hash-table from arguments (see {Requirements on KEY_CONFIG});