std::ranges::swap (3) Linux Manual Page
std::ranges::swap – std::ranges::swap
Synopsis
Defined in header<concepts>
inline namespace /* unspecified */
{
(since C++ 20)
inline constexpr /* unspecified */ swap = /* unspecified */;
(customization point object)
}
Call signature
template <class T, class U>
requires /* see below */
constexpr void
swap(T &&t, U &&u) noexcept(/* see below */);Exchanges the values referenced by t and u.
A call to ranges::swap is equivalent to:
1) (void)swap(std::forward<T>(t), std::forward<U>(u)), if that expression is valid, where the overload_resolution is performed with the following candidates:
*template <class T>
void swap(T &, T &) = delete;
*template <class T, std::size_t N>
void swap(T (&)[N], T (&)[N]) = delete;
*any declarations of swap found by argument - dependent_lookup.If the function selected by overload resolution does not exchange the values referenced by t and u, the program is ill-formed; no diagnostic required.
2) Otherwise, (void)ranges::swap_ranges(t, u), if T and U are lvalue references to array types of equal extent (but possibly different element types) and ranges::swap(*t, *u) is a valid expression;
3) Otherwise, if T and U are both V& for some type V that meets the syntactic requirements of MoveConstructible<V> and Assignable<V&, V>, exchanges the referenced values as if by V v{std::move(t)}; t = std::move(u); u = std::move(v);. If the semantic requirements of either concept are not satisfied, the program is ill-formed; no diagnostic required.
4) In all other cases, a call to ranges::swap is ill-formed.
ranges::swap can be used in a constant expression if every function it calls (as specified above) can be so used.
Customization point objects
The name ranges::swap denotes a customization point object, which is a function_object of a literal Semiregular class type (denoted, for exposition purposes, as SwapT). All instances of SwapT are equal. Thus, ranges::swap can be copied freely and its copies can be used interchangeably.
Given a set of types Args…, if std::declval<Args>()… meet the requirements for arguments to ranges::swap above, SwapT will satisfy std::Invocable<const SwapT&, Args…>. Otherwise, no function call operator of SwapT participates in overload resolution.
Exceptions
1)
noexcept specification:
noexcept(noexcept((void)swap(std::forward<T>(t), std::forward<T>(u))))
, where swap is found as described above.
2)
noexcept specification:
noexcept(noexcept(ranges::swap(*t, *u)))
3)
noexcept specification:
noexcept(std::is_nothrow_move_constructible_v<V> &&
std::is_nothrow_move_assignable_v<V>)
Example
This section is incomplete
Reason: no example
See also
Swappable specifies that a type can be swapped or that two types can be swapped with each other
SwappableWith (concept)
(C++20)
swap (function template)