meta::output_iterator

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

template <typename I, typename T>
concept output_iterator =
   meta::input_or_output_iterator<I> &&
   meta::writable<I, T> &&
   requires(I i, T&& t) {
      *i++ = std::forward<T>(t);
   };

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

---

Concept emulation

namespace mgs {
namespace meta {

template <typename I, typename T>
struct is_output_iterator { /* ... */ };

template <typename I, typename T>
constexpr auto is_output_iterator_v = is_output_iterator<I, T>::value;

template <typename I, typename T,
          typename = std::enable_if_t<is_output_iterator_v<I, T>>>
using output_iterator = I;

} // namespace meta
} // namespace mgs

Example

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

using namespace mgs::meta;

static_assert(is_output_iterator_v<std::back_insert_iterator<std::string>>, "");
static_assert(is_output_iterator_v<char*>, "");

static_assert(!is_output_iterator_v<char const*>, "");
static_assert(!is_output_iterator_v<std::istreambuf_iterator<char>>, "");

See also

• meta::input_or_output_iterator

• meta::writable