std::variant::swap

C++

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Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

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Numerics library

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Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

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Technical Specifications

Utilities library

Type support (basic types, RTTI, type traits)
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Program utilities
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initializer_list (C++11)
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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
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strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
common_comparison_category
Common vocabulary types
pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
Swap, forward and move
swap
exchange (C++14)
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std::variant

Member functions

variant::variant

variant::~variant

variant::operator=

Observers

variant::index

variant::valueless_by_exception

Modifiers

variant::emplace

variant::swap

Non-member functions

visit

holds_alternative

get

get_if

operator==operator!=operator<operator<=operator>operator>=

swap

Helper classes

monostate

bad_variant_access

variant_size

variant_alternative

hash

Helper objects

variant_npos

void swap( variant& rhs ) noexcept(/* see below */);	(1)	(since C++17)

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<i>(*this), std:get<i>(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 behavior is undefined unless lvalues of type T_i are Swappable and std::is_move_constructible_v<T_i> is true for all T_i in Types....

Parameters

rhs

-

a variant object to swap with

Return value

(none)

Exceptions

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

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

noexcept specification:

noexcept(((std::is_nothrow_move_constructible_v<Types> &&
std::is_nothrow_swappable_v<Types>) && ...))