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std::ranges:: forward_range

From cppreference.net
C++
Ranges library
Range adaptors
Definido en el encabezado <ranges>
template < class T >

concept forward_range =

ranges:: input_range < T > && std:: forward_iterator < ranges:: iterator_t < T >> ;
(desde C++20)

El concepto forward_range es un refinamiento del range para el cual ranges::begin retorna un modelo de forward_iterator .

Ejemplo

Ejecutar este código 
#include <forward_list>
#include <queue>
#include <ranges>
#include <span>
#include <stack>
#include <tuple>
const char* str{"not a forward range"};
const char str2[] = "a forward range";
static_assert(
    std::ranges::forward_range<decltype("a forward range")> &&
    !std::ranges::forward_range<decltype(str)> &&
    std::ranges::forward_range<decltype(str2)> &&
    !std::ranges::forward_range<std::stack<char>> &&
    std::ranges::forward_range<std::forward_list<char>> &&
    !std::ranges::forward_range<std::tuple<std::forward_list<char>>> &&
    std::ranges::forward_range<std::span<char>> &&
    !std::ranges::forward_range<std::queue<char>> &&
"");
int main() {}