_Unique_keys Boolean value.True if the return value of _Hashtable::count(k) is always at most one, false if it may be an arbitrary number. This is true for unordered_set and unordered_map, false for unordered_multiset and unordered_multimap. 在由模板生成类代码的时候,会根据_Hashtable_tra...
Walking through a bucket's nodes requires a check on the hash code to see if each node is still in the bucket. Such a design assumes a quite efficient hash functor and is one of the reasons it is highly advisable to set __cache_hash_code to true. 如果不存在相同key的元素,_M_insert...