iterator.cpp

struct Iterator
{
    // constructor that takes in a pointer from the linked list
    Iterator() noexcept : current_node(nullptr){};
    Iterator(const node_ptr &node) noexcept : current_node(node.get()){};

    // incrementing means going through the list
    Iterator &operator++() noexcept
    {
        if (current_node != nullptr)
        {
            previous_node = current_node;
            current_node = current_node->next.get();
        }
        return *this;
    };

    // post fixing is bad in general but it has it's usages
    Iterator operator++(int) noexcept
    {
        Iterator tempIter = *this; // we make a copy of the iterator
        ++*this;                   // we increment
        return tempIter;           // we return the copy before increment
    };

    // we need to be able to compare nodes
    bool operator!=(const Iterator &other) const noexcept
    {
        return this->current_node != other.current_node;
    };

    // return the data from the node (dereference operator)
    Data operator*() const noexcept
    {
        return this->current_node->data;
    };

private:
    const Node *previous_node = nullptr;
    const Node *current_node = nullptr;
};