meta::common_range¶

Defined in header <mgs/meta/concepts/common_range.hpp>.

template <typename T>
concept common_range =
   meta::range<T> &&
   meta::same_as<meta::iterator_t<T>, meta::sentinel_t<T>>;

Pre-C++20 implementation of the std::ranges::common_range concept.

Concept emulation¶

namespace mgs {
namespace meta {

template <typename T>
struct is_common_range { /* ... */ };

template <typename T>
constexpr auto is_common_range_v = is_common_range<T>::value;

template <typename T,
          typename = std::enable_if_t<is_common_range_v<T>>>
using common_range = T;

} // namespace meta
} // namespace mgs

Example¶

#include <mgs/meta/concepts/common_range.hpp>

using namespace mgs::meta;

struct sentinel {};

bool operator==(char*, pointer_sentinel);
bool operator!=(char*, pointer_sentinel);

bool operator==(pointer_sentinel, char*);
bool operator!=(pointer_sentinel, char*);

struct input_range {
  char* begin();
  sentinel end();
};

static_assert(is_common_range_v<std::string>, "");
static_assert(!is_common_range_v<input_range>, "");

See also¶