STL之hashtable

template<class Value>
struct __hashtable_node
{
      __hashtable_node *next;
      Value val; 
};

template<class Value, class Key>
struct __hashtable_iterator
{
    typedef __hashtable_node<Value> node;
    typedef hashtable<Value, Key> hashtable;

    node *cur;
    hashtable *ht;

    __hashtable_iterator(node *n, hashtable *tab): cur(n), ht(tab){}
    __hashtable_iterator(){}
    
    reference operator*() const{ return cur->val;}
};

template<class Value, class Key>
class hashtable
{
 private:
     vector<node*> buckets;
     size_type num_elements;
};