functional style stdex::optional to std::vector conversion

optionalToVector.cpp

#include <experimental/optional>
#include <experimental/type_traits>
#include <type_traits>
#include <utility>
#include <vector>

namespace stdex = std::experimental;

template <
    typename Optional,
    typename = std::enable_if_t<
        stdex::is_same_v<
            std::decay_t<Optional>,
            stdex::optional<typename std::decay_t<Optional>::value_type>
        >
    >
>
std::vector<typename std::decay_t<Optional>::value_type> toVector(Optional&& optional)
{
    typedef typename std::decay_t<Optional>::value_type value_type;
    typedef std::conditional_t<
        stdex::is_lvalue_reference_v<Optional>,
        std::add_lvalue_reference_t<value_type>,
        value_type
    > value_type_forward;
    auto result = std::vector<value_type>{};
    if (optional)
        result.push_back(std::forward<value_type_forward>(*optional));
    return result;
}