std::ranges::range_adaptor_closure
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range_adaptor_closure
(C++23)
Defined in header
<ranges>
template< class D >
(since C++23)
requires std::is_object_v <D> && std::same_as <D, std::remove_cv_t <D>>
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
rangeargument. -
Thas exactly one public base class ranges::range_adaptor_closure<T>, andThas no base classes of type ranges::range_adaptor_closure<U> for any other typeU. -
Tdoes not satisfyrange.
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_ranges |
202202L |
(C++23) | std::ranges::range_adaptor_closure
|
[edit] Example
Run this code
#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"); }