iter_swap(std::common_iterator)

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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)
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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)
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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)
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std::common_iterator

成员函数

common_iterator::common_iterator

common_iterator::operator=

common_iterator::operator*common_iterator::operator->

common_iterator::operator++common_iterator::operator++(int)

非成员函数

operator== (C++20)

operator- (C++20)

iter_move (C++20)

iter_swap (C++20)

辅助类

incrementable_traits<std::common_iterator> (C++20)

iterator_traits<std::common_iterator> (C++20)

 

<tbody> </tbody>

template< std::indirectly_swappable<I> I2, class S2 > friend constexpr void iter_swap( const common_iterator& x, const std::common_iterator<I2, S2>& y ) noexcept(/* 见下文 */);		(C++20 起)

交换两个底层迭代器所指向的对象。若 x 不保有 I 对象或 y 不保有 I2 对象（即 x 与 y 中至少一个不保有迭代器）则行为未定义。

函数体等价于 ranges​::​iter_swap(std::get<I>(x.var), std::get<I2>(y.var))。

此函数模板对常规的无限定或有限定查找不可见，而只能在 std::common_iterator&ltI,S> 为实参的关联类时由实参依赖查找找到。

参数

x, y

-

指向要交换的元素的迭代器

返回值

（无）

复杂度

常数。

异常

noexcept 说明：  

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

示例

运行此代码

#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");
}

输出：

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

缺陷报告

下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。

缺陷报告	应用于	出版时的行为	正确行为
LWG 3574	C++20	variant 为完全 constexpr (P2231R1) 但 common_iterator 不是	亦使之为 constexpr

参阅

swap	交换两个对象的值 (函数模板)
swap_ranges	交换两个范围的元素 (函数模板)
iter_swap	交换两个迭代器所指向的元素 (函数模板)
iter_swap (C++20)	交换两个可解引用对象所引用的值 (定制点对象)
iter_swap (C++20)	交换两个底层迭代器所指向的对象 (函数模板)