The header <functional> has the following additions:
namespace std {
template <class Predicate> class unary_negate;
template <class Predicate>
constexpr unary_negate<Predicate> not1(const Predicate&);
template <class Predicate> class binary_negate;
template <class Predicate>
constexpr binary_negate<Predicate> not2(const Predicate&);
}
Negators not1 and not2 take a unary and a binary predicate, respectively, and return their logical negations ([expr.unary.op]).
template <class Predicate>
class unary_negate {
public:
constexpr explicit unary_negate(const Predicate& pred);
constexpr bool operator()(const typename Predicate::argument_type& x) const;
using argument_type = typename Predicate::argument_type;
using result_type = bool;
};
constexpr bool operator()(const typename Predicate::argument_type& x) const;
Returns: !pred(x).
template <class Predicate>
constexpr unary_negate<Predicate> not1(const Predicate& pred);
Returns: unary_negate<Predicate>(pred).
template <class Predicate>
class binary_negate {
public:
constexpr explicit binary_negate(const Predicate& pred);
constexpr bool operator()(const typename Predicate::first_argument_type& x,
const typename Predicate::second_argument_type& y) const;
using first_argument_type = typename Predicate::first_argument_type;
using second_argument_type = typename Predicate::second_argument_type;
using result_type = bool;
};
constexpr bool operator()(const typename Predicate::first_argument_type& x,
const typename Predicate::second_argument_type& y) const;
Returns: !pred(x,y).
template <class Predicate>
constexpr binary_negate<Predicate> not2(const Predicate& pred);
Returns: binary_negate<Predicate>(pred).