20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.9 Logical operations [logical.operations]

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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]).

20.14.9.1 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;
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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));
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Returns: std​::​forward<T>(t) && std​::​forward<U>(u).

20.14.9.2 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;
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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));
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Returns: std​::​forward<T>(t) || std​::​forward<U>(u).

20.14.9.3 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;
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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));
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Returns: !std​::​forward<T>(t).