std::ranges::iter_swap
Defined in header <iterator> |
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---|---|---|
inline namespace /*unspecified*/ { inline constexpr /*unspecified*/ iter_swap = /*unspecified*/; } |
(since C++20) (customization point object) |
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Call signature | ||
template< class I1, class I2 > requires /* see below */ constexpr void iter_swap( I1&& i1, I2&& i2 ) noexcept(/* see below */); |
(since C++20) |
Swaps values denoted by two iterators.
A call to ranges::iter_swap
is expression-equivalent to:
-
(void)iter_swap(std::forward<I1>(i1), std::forward<I2>(i2))
, if eitherstd::remove_cvref_t<I1>
orstd::remove_cvref_t<I2>
is a class or enumeration type and the expression is well-formed in unevaluated context, where the overload resolution is performed with the following candidates:-
void iter_swap(auto, auto) = delete;
- any declarations of
iter_swap
found by argument-dependent lookup.
i1
andi2
, the program is ill-formed, no diagnostic required. -
- otherwise,
ranges::swap(*std::forward<I1>(i1), *std::forward<I2>(i2))
if bothI1
andI2
modelindirectly_readable
and ifstd::iter_reference_t<I1>
andstd::iter_reference_t<I2>
modelswappable_with
. - otherwise,
(void)(*std::forward<I1>(i1) = /*iter_exchange_move*/(std::forward<I2>(i2), std::forward<I1>(i1)))
, ifI1
andI2
modelstd::indirectly_movable_storable<I1, I2>
andstd::indirectly_movable_storable<I2, I1>
, whereiter_exchange_move
is an exposition-only function template described below.
In all other cases, a call to ranges::iter_swap
is ill-formed, which can result in substitution failure when ranges::iter_swap(e1, e2)
appears in the immediate context of a template instantiation.
The exposition-only function template iter_exchange_move
is equivalently defined as:
template<class X, class Y> constexpr std::iter_value_t<X> /*iter_exchange_move*/(X&& x, Y&& y) noexcept(noexcept(std::iter_value_t<X>(std::ranges::iter_move(x)) && noexcept(*x = std::ranges::iter_move(y)))) { std::iter_value_t<X> old(std::ranges::iter_move(x)); *x = std::ranges::iter_move(y); return old; }
Expression-equivalent
Expression e
is expression-equivalent to expression f
, if.
-
e
andf
have the same effects, and - either both are constant subexpressions or else neither is a constant subexpression, and
- either both are potentially-throwing or else neither is potentially-throwing (i.e.
noexcept(e) == noexcept(f)
).
Customization point objects
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.
See also
(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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