iter_move(std::common_iterator)
From cppreference.com
< cpp | iterator | common iterator
friend constexpr decltype(auto) iter_move( const std::common_iterator& i ) noexcept(noexcept(ranges::iter_move(std::declval<const 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 std::ranges::iter_move(std::get<I>(i.var));.
This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::common_iterator<I, S> is an associated class of the arguments.
If i.var does not hold an I
object (i.e. an iterator), 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
Run this code
#include <iomanip> #include <iostream> #include <iterator> #include <string> #include <vector> void print(auto const& rem, auto const& v) { std::cout << rem << '[' << size(v) << "] { "; for (int o{}; auto const& s : v) std::cout << (o++ ? ", " : "") << std::quoted(s); std::cout << " }\n"; } int main() { std::vector<std::string> p{"Andromeda", "Cassiopeia", "Phoenix"}, q; print("p", p); print("q", q); using CTI = std::counted_iterator<std::vector<std::string>::iterator>; using CI = std::common_iterator<CTI, std::default_sentinel_t>; CI last{std::default_sentinel}; for (CI first{{p.begin(), 2}}; first != last; ++first) q.emplace_back(/* ADL */ iter_move(first)); print("p", p); print("q", q); }
Possible output:
p[3] { "Andromeda", "Cassiopeia", "Phoenix" } q[0] { } p[3] { "", "", "Phoenix" } q[2] { "Andromeda", "Cassiopeia" }
[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) |
(C++20) |
casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function) |
(C++11) |
converts the argument to an xvalue (function template) |
(C++11) |
converts the argument to an xvalue if the move constructor does not throw (function template) |
(C++11) |
forwards a function argument and use the type template argument to preserve its value category (function template) |
(C++20) |
moves a range of elements to a new location (niebloid) |
(C++20) |
moves a range of elements to a new location in backwards order (niebloid) |