Defined in header <iterator> | ||
---|---|---|
namespace ranges { inline namespace /* unspecified */ { inline constexpr /* unspecified */ iter_swap = /* unspecified */; } } | (since C++20) (customization point object) | |
Call signature | ||
template< class I1, class I2 > constexpr void iter_swap( I1&& i1, I2&& i2 ) noexcept(/* see below */); | (since C++20) | |
Helper function | ||
template< class X, class Y > constexpr std::iter_value_t<X> iter-exchange-move( X&& x, Y&& y ) // exposition only noexcept(noexcept(std::iter_value_t<X>(std::ranges::iter_move(x))) && noexcept(*x = std::ranges::iter_move(y))); |
Swaps values denoted by two iterators.
The effect of the exposition-only helper function iter-exchange-move
is equivalent to.
std::iter_value_t<X> old(std::ranges::iter_move(x)); *x = std::ranges::iter_move(y); return old;
ranges::iter_swap(i1, i2)
is expression-equivalent to:
(void)iter_swap(i1, i2)
, if i1
or i2
has a class or enumeration type and the expression is well-formed, where the overload resolution of iter_swap
is performed with the additional candidate void iter_swap(auto, auto) = delete;
^{[1]}, excluding std::ranges::iter_swap
itself. i1
and i2
, the program is ill-formed, no diagnostic required. ranges::swap(*i1, *i2)
if both I1
and I2
model indirectly_readable
and if std::iter_reference_t<I1> and std::iter_reference_t<I2> model swappable_with
. (void)(*i1 = iter-exchange-move(i2, i1))
, if std::indirectly_movable_storable<I1, I2>
and std::indirectly_movable_storable<I2, I1>
are both modeled, except that i1
is only evaluated once. ranges::iter_swap(i1, i2)
is ill-formed, which can result in substitution failure when ranges::iter_swap(i1, i2)
appears in the immediate context of a template instantiation. std::iter_swap
. The name ranges::iter_swap
denotes a customization point object, which is a const function object of a literal semiregular
class type. For exposition purposes, the cv-unqualified version of its type is denoted as __iter_swap_fn
.
All instances of __iter_swap_fn
are equal. The effects of invoking different instances of type __iter_swap_fn
on the same arguments are equivalent, regardless of whether the expression denoting the instance is an lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified instance is not required to be invocable). Thus, ranges::iter_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::iter_swap
above, __iter_swap_fn
models
.
std::invocable<__iter_swap_fn, Args...>
, std::invocable<const __iter_swap_fn, Args...>
, std::invocable<__iter_swap_fn&, Args...>
, and std::invocable<const __iter_swap_fn&, Args...>
.Otherwise, no function call operator of __iter_swap_fn
participates in overload resolution.
(C++20) | swaps the objects pointed to by two adjusted underlying iterators (function template) |
(C++20) | swaps the objects pointed to by two underlying iterators (function template) |
swaps the elements pointed to by two iterators (function template) |
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