NAME¶

std::ranges::elements_of - std::ranges::elements_of

Synopsis¶

Defined in header <ranges>
template< ranges::range R, class Allocator =
std::allocator<std::byte> > (since C++23)
struct elements_of;

Encapsulates a range. Specializations of elements_of act as a tag in overload sets
to disambiguate when a range should be treated as a sequence rather than a single
value.

Template parameters¶

R - a type that satisfies range
Allocator - an allocator type that meets the requirements of Allocator

Data members

Member name Definition
range a range of type R
(public member object)
an allocator of type Allocator. It has default member initializer that
allocator value initializes itself
(public member object)

All these members are declared with [[no_unique_address]] attribute.

Deduction guide

template< class R, class Allocator = std::allocator<std::byte> >
elements_of( R&&, Allocator = Allocator() ) -> elements_of<R&&, (since C++23)
Allocator>;

Example¶

// Run this code

#include <any>
#include <generator>
#include <iostream>
#include <ranges>
#include <string_view>

template<bool Elementwise>
std::generator<std::any> gen(std::ranges::input_range auto&& r)
{
if constexpr (Elementwise)
co_yield std::ranges::elements_of(r); // yield each element of r
else
co_yield r; // yield r as a single value
}

int main()
{
auto test = std::string_view{"test"};

for (std::any a : gen<true>(test))
std::cout << '[' << std::any_cast<char>(a) << "] ";
std::cout << '\n';

for (std::any a : gen<false>(test))
std::cout << '[' << std::any_cast<std::string_view>(a) << "] ";
std::cout << '\n';
}

Output:¶

[t] [e] [s] [t]
[test]

References¶

* C++23 standard (ISO/IEC 14882:2023):

* 26.5.6 Class template elements_of [range.elementsof]