optional-dummy.cc

#include <optional>
#include <string>
#include <random>
#include <ranges>
#include <functional>

using namespace std::literals::string_literals;

template <typename T>
class avi_optional {
    bool _engaged = false;
    T _value;
public:
    avi_optional(std::nullopt_t) : _engaged(false), _value() {}
    avi_optional(T&& in) : _engaged(true), _value(std::move(in)) {}
};

template <template <typename T> class Optional>
void
run_test() {
    auto gen_bool = std::bind(std::uniform_int_distribution<>(0, 1),
                              std::default_random_engine());
    using opt_string = Optional<std::string>;
    auto v_ref
        = std::views::iota(0, 10000)
        | std::views::transform([&] (auto ignore) {
            return gen_bool() ? opt_string(std::nullopt) : opt_string("xyz");
          })
        | std::ranges::to<std::vector>();
    for (unsigned i = 0; i < 1000000; ++i) {
        auto v_copy = v_ref;
    }
}

int main(int ac, char** av) {
    if (ac >= 2 && av[1] == "a"s) {
        run_test<avi_optional>();
    } else {
        run_test<std::optional>();
    }
    return 0;
}