std::variant<Types...>::swap - cppreference.com (original) (raw)

| void swap( variant& rhs ) noexcept(/* see below */); | | (since C++17) (constexpr since C++20) | | ------------------------------------------------------ | | ------------------------------------- |

Swaps two variant objects.

• If both *this and rhs are valueless by exception, does nothing.
• Otherwise, if both *this and rhs hold the same alternative, calls swap(*std::get_if<i>(this), *std::get_if<i>(std::addressof(rhs))) where i is index(). If an exception is thrown, the state of the values depends on the exception safety of the swap function called.
• Otherwise, exchanges values of rhs and *this. If an exception is thrown, the state of *this and rhs depends on exception safety of variant's move constructor.

The program is ill-formed unless type T_i are Swappable and std::is_move_constructible_v<T_i> is true for all T_i in Types....

Contents

• 1 Parameters
• 2 Return value
• 3 Exceptions
• 4 Notes
• 5 Example
• 6 Defect reports
• 7 See also

[edit] Parameters

[edit] Return value

(none)

[edit] Exceptions

If this->index() == rhs.index(), may throw any exception thrown by swap(*std::get_if<i>(this), *std::get_if<i>(std::addressof(rhs))) with i being index().

Otherwise, may throw any exception thrown by the move constructors of the alternatives currently held by *this and rhs.

[edit] Notes

[edit] Example

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also