A generic hash table

> Hash maps were invented in the fifties. C++ has been a popular language since the eighties. The fact that they couldn't design a hash table implementation that was good enough to slap a sticker on it in 1998
Not in 1998 but in late 1995 (that's when the final drafts were produced). And the whole idea of STL was pretty new at that point, it's actually a small miracle they managed to put it into the C++ Standard as it is.

> Do you want an open addressing implementation? What type of probing? A Cuckoo hash? Do you use a linked list to allow ordered iteration? Do you allow hash table modification during iteration? If so, only using that iterator or arbitrary insertions? What resize strategy do you use when growing the table? What resize strategy do you use when shrinking the table? Do you store precalculated hash codes in the table? Do you use tombstones to mark deleted entries?

You've described about 100 different structures (considering various permutations). Some of the functionality can be split into policies (they work wonderfully with templates, incidentally). Otherwise, library designers just pick a generic enough version and go along with it.

If you need some special tuned version for your very specific need - you're welcome to write it. If you abide by STL's standards then you can even use them with STL/Boost algorithms. Without any loss of performance, I might add.