Method capacity

src/prevector.h:311–317

    const_reverse_iterator rend() const { return const_reverse_iterator(item_ptr(-1)); }

    size_t capacity() const {
        if (is_direct()) {
            return N;
        } else {
            return _union.capacity;
        }
    }

    T& operator[](size_type pos) {
        return *item_ptr(pos);