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ara::core::Variant

A type-safe union that behaves like std::variant from C++17.

ara::core::Variant<int, float> v, w;
v = 42; // v contains int
int i = ara::core::get<int>(v);
w = ara::core::get<int>(v);
w = ara::core::get<0>(v); // same effect as the previous line
w = v; // same effect as the previous line
  • Parameters
    • Ts the types that the Variant is able to hold

class ara::core::Variant​

This class defines a type safe union. The definition of this class is based on C++17 std::variant. Wherever needed, please refer to C++17 standard for more information.

Members​

public template<>
inline constexpr Variant()​

Default constructor. Constructs a variant holding the value-initialized value of the first alternative.

public Variant(const Variant & other) = default​

Copy constructor.

  • Parameters
    • other other Variant from which to construct.

public Variant(Variant && other) = default​

Move constructor.

  • Parameters
    • other other Variant from which to construct.

public template<>
inline constexpr Variant(Arg && arg)​

Constructs a variant with the specified alternative T and initializes the contained value with the arguments std::forward<Args>(args)...

  • Parameters

    • Arg type of arguments

  • Parameters

    • arg arguments to initialize the contained value with

public template<>
inline constexpr explicit Variant(in_place_index_t< I >, Args &&... args)​

Constructs a variant with the alternative T_i specified by the index I and initializes the contained value with the arguments std::forward<Args>(args)....

  • Parameters

    • I index
    • Args type of argument

  • Parameters

    • args arguments to initialize the contained value with

public template<>
inline constexpr explicit Variant(in_place_index_t< I >, std::initializer_list< Up > il, Args &&... args)​

Constructs a variant with the alternative T_i specified by the index I and initializes the contained value with the arguments std::forward<Args>(args)....

  • Parameters

    • I index
    • Args type of argument

  • Parameters

    • args arguments to initialize the contained value with

public template<>
inline constexpr explicit Variant(in_place_type_t< T >, Args &&... args)​

Constructs a variant with the specified alternative T and initializes the contained value with the arguments std::forward<Args>(args)....

  • Parameters
    • T alternative type
    • Args type of arguments

public template<>
inline constexpr explicit Variant(in_place_type_t< T >, std::initializer_list< Up > il, Args &&... args)​

Constructs a variant with the specified alternative T and initializes the contained value with the arguments il, std::forward<Args>(args)....

  • Parameters
    • T type of alternative
    • Up type of il
    • Args type of arguments

public ~Variant() = default​

Destroy the Variant object.

public Variant&operator=(const Variant &) = default​

Assigns a new value to an existing variant object. Please refer to the C++17 std::variant documentation for more details.

public Variant&operator=(Variant &&) = default​

Move assigns a new value to an existing variant object. Please refer to the C++17 std::variant documentation for more details.

public template<>
inline Variant&operator=(Arg && arg)​

In place assignment.

  • Parameters

    • Arg Type of arguments

  • Parameters

    • arg arguments

  • Returns Variant& this variant

public template<>
inline T & emplace(Args &&... args)​

public template<>
inline T & emplace(std::initializer_list< Up > il, Args &&... args)​

public inline constexpr bool valueless_by_exception() const noexcept​

Returns false if and only if the variant holds a value.

  • Returns true variant doesn't hold a value

  • Returns false if and only if the variant holds a value

public inline constexpr std::size_t index() const noexcept​

Returns the zero-based index of the alternative that is currently held by the variant.

  • Returns constexpr std::size_t zero-based index of the alternative

public template<>
inline void swap(Variant & that)​

Swaps two variant objects. Please refer to C++17 std::variant for more details.

  • Parameters
    • that a variant object to swap with