std::ranges::borrowed_iterator_t, std::ranges::borrowed_subrange_t

 

C++

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功能特性测试宏 (C++20)

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概念库 (C++20)

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符号索引

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范围库

范围访问 begin cbegin   end cend rbegin crbegin   rend crend size ssize   data cdata empty

范围转换 std::from_range_t std::from_range (C++23)(C++23)     to (C++23)

悬垂迭代器处理 dangling borrowed_iterator_t borrowed_subrange_t

范围原语
range_size_trange_difference_trange_value_t elements_of (C++23)	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_reference_trange_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)

范围概念
range borrowed_range    sized_range	common_range view viewable_range	input_range output_range forward_range	bidirectional_range    random_access_range contiguous_range	constant_range (C++23)

视图
view_interface	subrange

范围工厂
empty_viewviews::empty	single_viewviews::single	basic_istream_viewviews::istream	iota_viewviews::iota	repeat_viewviews::repeat (C++23)(C++23)

范围适配器
views::all_tviews::all ref_view owning_view as_rvalue_viewviews::as_rvalue (C++23)(C++23)   filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while concat_viewviews::concat (C++26)(C++26)	drop_viewviews::drop drop_while_viewviews::drop_while join_viewviews::join join_with_viewviews::join_with (C++23)(C++23)   lazy_split_viewviews::lazy_split split_viewviews::split views::counted common_viewviews::common	reverse_viewviews::reverse as_const_viewviews::as_const (C++23)(C++23) elements_viewviews::elements keys_viewviews::keys values_viewviews::values enumerate_viewviews::enumerate (C++23)(C++23) zip_viewviews::zip (C++23)(C++23) zip_transform_viewviews::zip_transform (C++23)(C++23)	adjacent_viewviews::adjacent (C++23)(C++23) views::pairwise (C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23) views::pairwise_transform (C++23) chunk_viewviews::chunk (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23) stride_viewviews::stride (C++23)(C++23) cartesian_product_viewviews::cartesian_product (C++23)(C++23)

范围生成器 std::generator (C++23)

范围适配器闭包对象 range_adaptor_closure (C++23)

范围适配器对象

辅助项
copyable-box movable-box (C++23 前)  (C++23)	simple-view non-propagating-cache

 

在标头 <ranges> 定义
template< ranges::range R > using borrowed_iterator_t = /* 见下文 */;	(1)	(C++20 起)
template< ranges::range R > using borrowed_subrange_t = /* 见下文 */;	(2)	(C++20 起)

1) 若 R 实现 borrowed_range 则为 std::ranges::iterator_t<R>，否则为 std::ranges::dangling。

2) 若 R 实现 borrowed_range 则为 std::ranges::subrange<std::ranges::iterator_t<R>>，否则为 std::ranges::dangling。

某些受约束算法使用这两个模板别名以避免返回潜在悬垂的迭代器或视图。

可能的实现

borrowed_iterator_t
template< std::ranges::range R > using borrowed_iterator_t = std::conditional_t<std::ranges::borrowed_range<R>, std::ranges::iterator_t<R>, std::ranges::dangling>;
borrowed_subrange_t
template< std::ranges::range R > using borrowed_subrange_t = std::conditional_t<std::ranges::borrowed_range<R>, std::ranges::subrange<std::ranges::iterator_t<R>>, std::ranges::dangling>;

参阅

ranges::dangling (C++20)

占位类型，指示不应返回迭代器或子范围，因为它可能悬垂 (类)