Currently the const_iterator of UnorderedFastKeyTable ("UFKT") is not STL-compliant. This makes it a compiler error to fill an STL container using UFKT iterators, e.g.

StringMap<int> foo; // just a typedef'd UKFT
// do stuff with foo ...
std::vector<std::pair<std::string, int>> bar(foo.begin(), foo.end())

To fix this it is necessary to add these typedefs to the definition of UFKT::const_iterator :

iterator_category
value_type
difference_type
pointer
reference