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iter_move(std::counted_iterator)

From cppreference.com
 
 
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)

Iterator adaptors
Iterator customization points
Iterator operations
(C++11)    
(C++11)
Range access
(C++11)(C++14)
(C++14)(C++14)    
(C++11)(C++14)
(C++14)(C++14)    
(C++17)(C++20)
(C++17)
(C++17)
 
 
friend constexpr decltype(auto) iter_move( const std::counted_iterator& i )

    noexcept(noexcept(ranges::iter_move(i.base())))

        requires std::input_iterator<I>;
(since C++20)

Casts the result of dereferencing the underlying iterator to its associated rvalue reference type.

The function body is equivalent to return ranges::iter_move(i.base());.

This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::counted_iterator<I> is an associated class of the arguments.

If i.count() is equal to 0, the behavior is undefined.

Contents

[edit] Parameters

i - a source iterator adaptor

[edit] Return value

An rvalue reference or a prvalue temporary.

[edit] Complexity

Constant.

[edit] Example

#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
void print(auto const& rem, auto const& v)
{
    std::cout << rem << '[' << size(v) << "] {";
    for (char comma[]{0, ' ', 0}; auto const& s : v)
        std::cout << comma << std::quoted(s), *comma = ',';
    std::cout << "}\n";
}
 
int main()
{
    std::vector<std::string> p{"Alpha", "Bravo", "Charlie"}, q;
    print("p", p);
    print("q", q);
 
    using RI = std::counted_iterator<std::vector<std::string>::iterator>;
 
    for (RI iter{p.begin(), 2}; iter != std::default_sentinel; ++iter)
        q.emplace_back(/* ADL */ iter_move(iter));
 
    print("p", p);
    print("q", q);
}

Possible output:

p[3] {"Alpha", "Bravo", "Charlie"}
q[0] {}
p[3] {"", "", "Charlie"}
q[2] {"Alpha", "Bravo"}

[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 3953 C++20 the return type was std::iter_rvalue_reference_t<I> changed to decltype(auto)

[edit] See also

(C++20)
casts the result of dereferencing an object to its associated rvalue reference type
(customization point object)[edit]
(C++20)
swaps the objects pointed to by two underlying iterators
(function template) [edit]
(C++11)
obtains an rvalue reference
(function template) [edit]
obtains an rvalue reference if the move constructor does not throw
(function template) [edit]
(C++11)
forwards a function argument
(function template) [edit]
moves a range of elements to a new location
(niebloid)[edit]
moves a range of elements to a new location in backwards order
(niebloid)[edit]