A comparison functor. Transforms any comparison functor operating on logical keys to a comparison functor operating on order statistics keys.
| Parameter | Description | Default Value | 
| Cmp_Fn | Comparison functor. | std::less<Key> | 
| Allocator | Allocator type. The allocator is only used for definitions, e.g., size_type, pointer, and reference. | std::allocator<char> | 
| Class | Derivation Type | 
| std::binary_function<
  order_statistics_key<
    typename Cmp_Fn::first_argument_type, Allocator>,
  order_statistics_key<
    typename Cmp_Fn::second_argument_type, Allocator>,
  bool> | public | 
| Type | Definition | Description | 
| allocator | Allocator | Allocator type. | 
| cmp_fn | Cmp_Fn | Comparison functor type. | 
| Type | Definition | Description | 
| key_type | order_statistics_key<
    typename Cmp_Fn::first_argument_type, Allocator> | Key type. | 
| const_key_reference | typename allocator::template rebind< key_type>::other::const_reference | Const key reference type. | 
| Method | Description | 
| inline order_statistics_key_cmp () | Default constructor. | 
| inline order_statistics_key_cmp (const Cmp_Fn &r_cmp_fn) | Constructor taking a comparison functor. | 
| Method | Description | 
| inline bool operator() (const_key_reference r_lhs_key, const_key_reference r_rhs_key) const | Compares two keys. | 
| Method | Description | 
| inline cmp_fn & get_cmp_fn () | Access to the comparison functor object used. | 
| inline const cmp_fn & get_cmp_fn () const | Const access to the comparison functor object used. |