meta::random_access_iterator¶

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

template <typename I>
concept random_access_iterator =
   meat::bidirectional_iterator<I> &&
   meat::derived_from<meta::iter_concept<I>, std::random_access_iterator_tag> &&
   meat::totally_ordered<I> &&
   meat::sized_sentinel_for<I, I> &&
   requires(I i, I const j, meta::iter_difference_t<I> const n) {
      { i += n } -> meta::same_as<I&>;
      { j +  n } -> meta::same_as<I>;
      { n +  j } -> meta::same_as<I>;
      { i -= n } -> meta::same_as<I&>;
      { j -  n } -> meta::same_as<I>;
      {   j[n] } -> meta::same_as<meta::iter_reference_t<I>>;
   };

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

Concept emulation¶

namespace mgs {
namespace meta {

template <typename I>
struct is_random_access_iterator { /* ... */ };

template <typename I>
constexpr auto is_random_access_iterator_v = is_random_access_iterator<I>::value;

template <typename I,
          typename = std::enable_if_t<is_random_access_iterator_v<I>>>
using random_access_iterator = I;

} // namespace meta
} // namespace mgs

Example¶

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

using namespace mgs::meta;

static_assert(is_random_access_iterator_v<std::vector<int>::iterator>, "");
static_assert(is_random_access_iterator_v<char*>, "");
static_assert(!is_random_access_iterator_v<std::list<char>::iterator>, "");

See also¶