iter_swap(std::common_iterator)

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iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t

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std::common_iterator

Member functions
common_iterator::common_iterator
common_iterator::operator=
common_iterator::operator*common_iterator::operator->
common_iterator::operator++common_iterator::operator++(int)
Non-member functions
operator== (C++20)
operator- (C++20)
iter_move (C++20)
iter_swap (C++20)
Helper classes
incrementable_traits<std::common_iterator> (C++20)
iterator_traits<std::common_iterator> (C++20)

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template<std::indirectly_swappable<I> I2,class S2> friendconstexprvoid iter_swap(const common_iterator& x, conststd::common_iterator<I2, S2>& y)noexcept(/see below/);		(since C++20)

Swaps the objects pointed to by two underlying iterators. The behavior is undefined ifx does not hold anI object ory does not hold anI2 object (i.e. at least one ofx andy does not hold an iterator).

The function body is equivalent toranges::iter_swap(std::get<I>(x.var), std::get<I2>(y.var)).

This function template is not visible to ordinaryunqualified orqualified lookup, and can only be found byargument-dependent lookup when std::common_iterator<I,S> is an associated class of the arguments.

[edit]Parameters

x, y

the iterators to the elements to swap

[edit]Return value

(none)

[edit]Complexity

Constant.

[edit]Exceptions

noexcept specification:

noexcept(noexcept(ranges::iter_swap(std::declval<const I&>(),std::declval<const I2&>())))

[edit]Example

Run this code

#include <algorithm>#include <iostream>#include <iterator>#include <string>#include <vector> int main(){std::vector<std::string> v1{"1","2","3","4","5"},                             v2{"α","β","γ","δ","ε"}; using CI=std::common_iterator<std::counted_iterator<std::vector<std::string>::iterator>,std::default_sentinel_t>;     CI first1{std::counted_iterator{v1.begin(),3}};    CI first2{std::counted_iterator{v2.begin(),4}};    CI last{std::default_sentinel}; auto print=[&](auto rem){std::cout<< rem<<"v1 = ";        std::ranges::copy(v1,std::ostream_iterator<std::string>{std::cout," "});std::cout<<"\nv2 = ";        std::ranges::copy(v2,std::ostream_iterator<std::string>{std::cout," "});std::cout<<'\n';};     print("Before iter_swap:\n"); for(; first1!= last&& first2!= last;++first1,++first2)        iter_swap(first1, first2);// ADL     print("After iter_swap:\n");}

Output:

Before iter_swap:v1 = 1 2 3 4 5 v2 = α β γ δ ε After iter_swap:v1 = α β γ 4 5 v2 = 1 2 3 δ ε

[edit]Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
LWG 3574	C++20	`variant` was fully constexpr (P2231R1) but`common_iterator` was not	also made constexpr

[edit]See also

swap	swaps the values of two objects (function template)[edit]
swap_ranges	swaps two ranges of elements (function template)[edit]
iter_swap	swaps the elements pointed to by two iterators (function template)[edit]
iter_swap (C++20)	swaps the values referenced by two dereferenceable objects (customization point object)[edit]
iter_swap (C++20)	swaps the objects pointed to by two underlying iterators (function template)[edit]