Function insert_range_impl

src/config/implementation.hpp:4051–4066

    template <class InputIt>
    void insert_range_impl(const_key_type& k, InputIt i, InputIt j)
    {
        insert_range_impl2(k, i, j);

        while (++i != j) {
            // Note: can't use get_key as '*i' might not be value_type - it
            // could be a pair with first_types as key_type without const or
            // a different second_type.
            //
            // TODO: Might be worth storing the value_type instead of the
            // key here. Could be more efficient if '*i' is expensive. Could
            // be less efficient if copying the full value_type is
            // expensive.
            insert_range_impl2(extractor::extract(*i), i, j);
        }
    }

    template <class InputIt>
    void insert_range_impl2(const_key_type& k, InputIt i, InputIt j)