meta::input_iterator¶

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

template <typename I>
concept input_iterator =
   meta::input_or_output_iterator<I> &&
   meta::readable<I> &&
   meta::derived_from<meta::iter_concept<I>, std::input_iterator_tag>;

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

Concept emulation¶

namespace mgs {
namespace meta {

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

template <typename I>
constexpr auto is_input_iterator_v = is_input_iterator<I>::value;

template <typename I,
          typename = std::enable_if_t<is_input_iterator_v<I>>>
using input_iterator = I;

} // namespace meta
} // namespace mgs

Example¶

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

using namespace mgs::meta;

static_assert(is_input_iterator_v<std::istreambuf_iterator<char>>, "");
static_assert(is_input_iterator_v<char*>, "");
// std::back_insert_iterator is an output_iterator
static_assert(!is_input_iterator_v<std::back_insert_iterator<std::string>>, "");

See also¶