PV913ListFw

#include <iostream>

template <typename ElemT>
class ListFw
{
    class Node
    {
    public:
        ElemT data;
        Node* next;
        Node(const ElemT& dataP, Node* nextP = nullptr)
            :data{ dataP }, next{ nextP }{};
    };

    Node* head;
    Node* tail;
    size_t size;
public:
    ListFw() : head{ nullptr }, tail{ nullptr }, size{ 0 } {}
    ElemT& front() { return head->data; };
    const ElemT& front()const { return head->data; };
    ElemT& back() { return tail->data; };
    const ElemT& back()const { return tail->data; };
    const size_t getSize() const { return size; };
    bool empty() const { return size == 0; };
    void push_back(const ElemT& data);
    void push_front(const ElemT& data);
    bool pop_back();
    bool pop_front();
    void clear();
    ~ListFw();
};

template <typename ElemT>
void ListFw<ElemT>::push_back(const ElemT& data)
{
    if (!head)
    {
        head = new Node{ data };
        tail = head;
    }
    else
    {
        tail->next = new Node{ data };
        tail = tail->next;
    }
    ++size;
}

template <typename ElemT>
void ListFw<ElemT>::push_front(const ElemT& data)
{
    head = new Node{ data, head };
    ++size;

    if (!tail)
    {
        tail = head;
    }
}

template <typename ElemT>
bool ListFw<ElemT>::pop_front()
{
    if (head)
    {
        Node* tmp{ head };
        head = head->next;
        delete tmp;
        --size;
        return true;
    }
    return false;
}

template <typename ElemT>
bool ListFw<ElemT>::pop_back()
{
    if (tail)
    {
        if (tail == head)
        {
            delete tail;
            size = 0;
            tail = nullptr;
            head = nullptr;
            return true;
        }

        //Node* curr{ head };

        //while (curr)
        for(Node* curr{ head }; curr; curr = curr->next)
        {
            if (curr->next == tail)
            {
                delete tail;
                curr->next = nullptr;
                tail = curr;
                --size;
                return true;
            }
            //curr = curr->next;
        }
    }
    return false;
}

template <typename ElemT>
void ListFw<ElemT>::clear()
{
    while (tail)
    {
        std::cout << "Clear for: " << back() << '\n';
        pop_back();
    }
}

template <typename ElemT>
ListFw<ElemT>::~ListFw()
{
    while (head)
    {
        std::cout << "Destruct for: " << front() << '\n';
        pop_front();
    }
}

int main()
{
    ListFw<int> l;
    std::cout << "Size: " << l.getSize() << '\n';

    l.push_back(42);
    l.push_back(33);

    std::cout << "Size: " << l.getSize() << '\n';
    std::cout << "Front: " << l.front() << '\n';
    std::cout << "Back: " << l.back() << '\n';
    l.pop_front();
    l.pop_back();
    std::cout << "Size: " << l.getSize() << '\n';

    l.push_back(1);
    l.push_back(2);
    l.push_back(3);
    l.push_back(4);
    std::cout << "Size: " << l.getSize() << '\n';
    std::cout << "Front: " << l.front() << '\n';
    std::cout << "Back: " << l.back() << '\n';

    l.clear();
    std::cout << "Size: " << l.getSize() << '\n';

    l.push_front(1);
    l.push_front(2);
    l.push_front(3);
    l.push_front(4);
    std::cout << "Size: " << l.getSize() << '\n';
    std::cout << "Front: " << l.front() << '\n';
    std::cout << "Back: " << l.back() << '\n';
}