std::iter_move(std::counted_iterator)

 

C++

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技术规范

 

迭代器库

迭代器概念
indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) input_or_output_iterator (C++20) sentinel_for (C++20) sized_sentinel_for (C++20)	input_iterator (C++20) output_iterator (C++20) forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
迭代器原语
iterator_traits input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20) iterator (C++17 中弃用)	incrementable_traits (C++20) indirectly_readable_traits (C++20) iter_value_titer_difference_titer_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++20)(C++20)
算法概念与工具
间接可调用概念
indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20) indirect_unary_predicate (C++20)	indirect_binary_predicate (C++20) indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
常用算法要求
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20) indirectly_copyable_storable (C++20)	indirectly_swappable (C++20) indirectly_comparable (C++20) permutable (C++20) mergeable (C++20) sortable (C++20)
工具
indirect_result_t	projected
迭代器适配器
reverse_iterator move_iterator (C++11) move_sentinel (C++20) common_iterator (C++20) counted_iterator (C++20) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20) back_inserter front_inserter inserter
流迭代器
istream_iterator ostream_iterator	istreambuf_iterator ostreambuf_iterator
迭代器定制点
ranges::iter_move (C++20)
ranges::iter_swap (C++20)
迭代器操作
advance distance prev (C++11) next (C++11)	ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)
范围访问
begincbegin (C++11)(C++14) endcend (C++11)(C++14) sizessize (C++17)(C++20)	rbegincrbegin (C++14)(C++14) rendcrend (C++14)(C++14) empty (C++17) data (C++17)

 

std::counted_iterator

成员函数

counted_iterator::counted_iterator (C++20)

counted_iterator::operator= (C++20)

counted_iterator::base (C++20)

counted_iterator::count (C++20)

counted_iterator::operator*counted_iterator::operator-> (C++20)(C++20)

counted_iterator::operator[] (C++20)

counted_iterator::operator++counted_iterator::operator++(int)counted_iterator::operator+counted_iterator::operator+=counted_iterator::operator--counted_iterator::operator--(int)counted_iterator::operator-counted_iterator::operator-= (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

非成员函数

operator==operator<=> (C++20)(C++20)

operator==(default_sentinel_t) (C++20)

operator+ (C++20)

operator- (C++20)

operator-(default_sentinel_t) (C++20)

iter_move (C++20)

iter_swap (C++20)

辅助类

iterator_traits (C++20)

 

friend constexpr std::iter_rvalue_reference_t<I>   iter_move( const std::counted_iterator& i )     noexcept(noexcept(ranges::iter_move(i.current)))       requires std::input_iterator<I>;		(C++20 起)

转型解引用底层迭代器的结果到其关联右值引用类型。若 i.count() 等于 ​0​ 则行为未定义。

函数体等价于 return ranges​::​iter_move(i.current); ，其中 current 为底层迭代器。

此函数对通常无限定或有限定查找不可见，而只能在 std::counted_iterator<I> 为参数的关联类时由实参依赖查找找到。

参数

i

-

源迭代器适配器

返回值

右值引用或纯右值临时量。

复杂度

常数。

示例

运行此代码

#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
void print(auto const& rem, auto const& v) {
    for (std::cout << rem << "[" << size(v) << "] { "; auto const& s : v)
        std::cout << quoted(s) << " ";
    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);
}

可能的输出：

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

参阅

iter_move (C++20)	将解引用迭代器的结果转型为其关联的右值引用类型 (定制点对象)
iter_swap (C++20)	交换二个底层迭代器所指向的对象 (函数模板)
move (C++11)	获得右值引用 (函数模板)
move_if_noexcept (C++11)	若移动构造函数不抛出则获得右值引用 (函数模板)
forward (C++11)	转发一个函数实参 (函数模板)
ranges::move (C++20)	将某一范围的元素移动到一个新的位置 (niebloid)
ranges::move_backword (C++20)	按从后往前的顺序移动某一范围的元素到新的位置 (niebloid)