Function make_iterator_impl

include/pybind11/pybind11.h:3391–3425

NOLINTNEXTLINE(performance-unnecessary-value-param)

          typename... Extra>
// NOLINTNEXTLINE(performance-unnecessary-value-param)
iterator make_iterator_impl(Iterator first, Sentinel last, Extra &&...extra) {
    using state = detail::iterator_state<Access, Policy, Iterator, Sentinel, ValueType, Extra...>;
    // TODO: state captures only the types of Extra, not the values

    // For Python < 3.14.0rc1, pycritical_section uses direct mutex locking (same as a unique
    // lock), which may deadlock during type registration. See detail/internals.h for details.
#if PY_VERSION_HEX >= 0x030E00C1 // 3.14.0rc1
    PYBIND11_LOCK_INTERNALS(get_internals());
#endif
    if (!detail::get_type_info(typeid(state), false)) {
        class_<state>(handle(), "iterator", pybind11::module_local())
            .def(
                "__iter__", [](state &s) -> state & { return s; }, pos_only())
            .def(
                "__next__",
                [](state &s) -> ValueType {
                    if (!s.first_or_done) {
                        ++s.it;
                    } else {
                        s.first_or_done = false;
                    }
                    if (s.it == s.end) {
                        s.first_or_done = true;
                        throw stop_iteration();
                    }
                    return Access()(s.it);
                    // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
                },
                std::forward<Extra>(extra)...,
                pos_only(),
                Policy);
    }

    return cast(state{std::forward<Iterator>(first), std::forward<Sentinel>(last), true});
}

PYBIND11_NAMESPACE_END(detail)