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;
template <class Predicate>
constexpr unary_negate<Predicate> not1(const 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;
template <class Predicate>
constexpr binary_negate<Predicate> not2(const Predicate& pred);