Реверс двусвязного списка

#include <iostream>
using namespace std;
 
 
class node
{
    public:
    node(const int data);
    int data;
    node* next;
    node* prev;
};
node::node(const int data): data(data), next(nullptr), prev(nullptr) {}
 
class dll
{
    public:
    dll();
    void push_front(const int data);
    void push_back(const int data);
    void reverse();
    void print_head() const;
    void print_tail() const;
    private:
    node* head;
    node* tail;
};
dll::dll(): head(nullptr), tail(nullptr) {}
 
void dll::push_front(const int data)
{
    node* tmp = new node(data);
    if(head)
    {
        head->prev = tmp;
        tmp->next = head;
        head = tmp;
    }
    else head = tail = tmp;
}
 
void dll::push_back(const int data)
{
    node* tmp = new node(data);
    if(head)
    {
        tail->next = tmp;
        tmp->prev = tail;
        tail = tmp;
    }
    else head = tail = tmp;
}
 
void dll::print_head() const
{
    node* curr = head;
    while(curr)
    {
        cout << curr->data << " ";
        curr = curr->next;
    }
}
 
void dll::print_tail() const
{
    node* curr = tail;
    while(curr)
    {
        cout << curr->data << " ";
        curr = curr->prev;
    }
}
 
void dll::reverse()
{
    node* curr = head, *tmp = nullptr;
    while(curr)
    {
        tmp = curr->prev;
        curr->prev = curr->next;
        curr->next = tmp;
        curr = curr->prev;
    }
}
 
int main(void)
{
    dll ll;
    ll.push_back(1);
    ll.push_back(2);
    ll.push_back(3);
    ll.push_back(4);
    ll.push_back(5);
    ll.push_back(6);
    ll.print_head();
    cout << endl;
    ll.print_tail();
    
 
    return EXIT_SUCCESS;
}

void dll::reverse()
{
    if (!head)
        return;
 
    node *head2 = tail = head;
    for (head = head->next; head; )
    {
        auto *p = head;
        head = head->next;
 
        p->next = head2;
        head2 = head2->prev = p;
    }
    head = head2;
    head->prev = tail->next = nullptr;
}

void dll::reverse()
{
    node* curr = head, * tmp = nullptr;
    while (curr)
    {
        tmp = curr->prev;
        curr->prev = curr->next;
        curr->next = tmp;
        curr = curr->prev;
    }
    head = (head && head->prev) ? tmp->prev : head;
}