20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.10 Logical operations [logical.operations]

20.14.10.1 General [logical.operations.general]

The library provides basic function object classes for all of the logical operators in the language ([expr.log.and], [expr.log.or], [expr.unary.op]).

20.14.10.2 Class template logical_and [logical.operations.and]

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template<class T = void> struct logical_and {
  constexpr bool operator()(const T& x, const T& y) const;
};

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constexpr bool operator()(const T& x, const T& y) const;

Returns: x && y.

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template<> struct logical_and<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) && std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) && std::forward<U>(u));

Returns: std::forward<T>(t) && std::forward<U>(u).

20.14.10.3 Class template logical_or [logical.operations.or]

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template<class T = void> struct logical_or {
  constexpr bool operator()(const T& x, const T& y) const;
};

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constexpr bool operator()(const T& x, const T& y) const;

Returns: x || y.

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template<> struct logical_or<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) || std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) || std::forward<U>(u));

Returns: std::forward<T>(t) || std::forward<U>(u).

20.14.10.4 Class template logical_not [logical.operations.not]

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template<class T = void> struct logical_not {
  constexpr bool operator()(const T& x) const;
};

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constexpr bool operator()(const T& x) const;

Returns: !x.

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template<> struct logical_not<void> {
  template<class T> constexpr auto operator()(T&& t) const
    -> decltype(!std::forward<T>(t));

  using is_transparent = unspecified;
};

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template<class T> constexpr auto operator()(T&& t) const
    -> decltype(!std::forward<T>(t));

Returns: !std::forward<T>(t).