std::ranges::range_adaptor_closure

 

C++

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Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range conversions
to (C++23)
Range primitives
range_size_trange_difference_trange_value_trange_reference_t	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)	elements_of (C++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Range factories
empty_viewviews::empty single_viewviews::single	iota_viewviews::iota repeat_viewviews::repeat (C++23)(C++23)	basic_istream_viewviews::istream
Range adaptors
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	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)
Range generators
std::generator (C++23)
Range adaptor objects
Range adaptor closure objects
range_adaptor_closure (C++23)
Helper items
copyable-box movable-box (until C++23)(C++23)	simple-view non-propagating-cache

 

Defined in header <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 is a helper class template for defining a RangeAdaptorClosureObject.

Let t be the object of type T, the implementation ensures that t is a range adaptor closure object if all the requirements are met:

• t is a unary function object that takes one range argument.
• T has exactly one public base class ranges::range_adaptor_closure<T>, and T has no base classes of type ranges::range_adaptor_closure<U> for any other type U.
• T does not satisfy range.

Example

Run this code

#include <iostream>
#include <ranges>
#include <string>
#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;
 
    std::string_view operator()(std::string_view sv) const {
        return sv.substr(start, end - start);
    }
};
 
int main() {
    std::string str = "01234567";
 
    Slice slicer{.start = 1, .end = 6};
 
    auto sv1 = slicer(str);  // use slicer as a normal function object
    auto sv2 = str | slicer; // use slicer as a range adaptor closure object
    std::cout << sv1 << '\n';
    std::cout << sv2 << '\n';
 
    // range adaptor closures can be composed
    auto slice_and_drop = slicer
                        | std::views::drop_while([](auto ch) { return ch != '3'; });
    std::cout << std::string_view(str | slice_and_drop) << '\n';
}

Output:

12345
12345
345