meta::incrementable¶

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

template <typename I>
concept incrementable =
   meta::regular<I> &&
   meta::weakly_incrementable<I> &&
   requires(I i) {
      { i++ } -> meta::same_as<I>;
   };

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

Concept emulation¶

namespace mgs {
namespace meta {

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

template <typename I>
constexpr auto is_incrementable_v = is_incrementable<I>::value;

template <typename I,
          typename = std::enable_if_t<is_incrementable_v<I>>>
using incrementable = I;

} // namespace meta
} // namespace mgs

Example¶

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

using namespace mgs::meta;

struct incrementable {
  using difference_type = void;
  incrementable& operator++();
  incrementable operator++(int);
};

struct non_incrementable {};

static_assert(is_incrementable_v<char>, "");
static_assert(is_incrementable_v<incrementable>, "");
static_assert(!is_incrementable_v<non_incrementable>, "");

See also¶