std::ranges::range_adaptor_closure

 

C++

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特性测试宏 (C++20)

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概念库 (C++20)

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元编程库 (C++11)

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技术规范

符号索引

外部库

 

范围库

范围访问 begin cbegin   end cend rbegin crbegin   rend crend size ssize   data cdata reserve_hint (C++26)   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    common_range	sized_range viewable_range    view	input_range output_range forward_range	bidirectional_range    random_access_range contiguous_range	approximately_sized_range (C++26) 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 as_rvalue_viewviews::as_rvalue (C++23)(C++23)   filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while common_viewviews::common views::counted to_input_viewviews::to_input (C++26)(C++26)	ref_view drop_viewviews::drop drop_while_viewviews::drop_while lazy_split_viewviews::lazy_split split_viewviews::split join_viewviews::join join_with_viewviews::join_with (C++23)(C++23)   concat_viewviews::concat (C++26)(C++26) cache_latest_viewviews::cache_latest (C++26)(C++26)	owning_view 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 (until C++23)  (C++23)	simple-view non-propagating-cache

 

定义于头文件 <ranges>
template< class D >     requires std::is_object_v<D> && std::same_as<D, std::remove_cv_t<D>> class range_adaptor_closure {};		(since C++23)

std::ranges::range_adaptor_closure 是一个辅助类模板，用于定义 RangeAdaptorClosureObject。

设 t 为 T 类型的对象，如果满足所有要求，则实现确保 t 是一个范围适配器闭包对象

• t 是一个一元函数对象，它接受一个 range 参数。
• T 恰好有一个公共基类 ranges::range_adaptor_closure<T>，并且对于任何其他类型 U，T 没有 ranges::range_adaptor_closure<U> 类型的基类。
• T 不满足 range。

注释

特性测试 宏	值	Std	特性
__cpp_lib_ranges	202202L	(C++23)	std::ranges::range_adaptor_closure

示例

运行此代码

#include <ranges>
#include <string_view>
 
// Define Slice as a range adaptor closure
struct Slice : std::ranges::range_adaptor_closure<Slice>
{
    std::size_t start = 0;
    std::size_t end = std::string_view::npos;
 
    constexpr std::string_view operator()(std::string_view sv) const
    {
        return sv.substr(start, end - start);
    }
};
 
int main()
{
    constexpr std::string_view str = "01234567";
 
    constexpr Slice slicer{.start = 1, .end = 6};
 
    // use slicer as a normal function object
    constexpr auto sv1 = slicer(str);
    static_assert(sv1 == "12345");
 
    // use slicer as a range adaptor closure object
    constexpr auto sv2 = str | slicer;
    static_assert(sv2 == "12345");
 
    // range adaptor closures can be composed
    constexpr auto slice_and_drop = slicer | std::views::drop(2);
    static_assert(std::string_view(str | slice_and_drop) == "345");
}