inherit a class DoublyLinkedStack

pr6.cpp

@@ -161,6 +161,67 @@ public:
     using LinkedList<T>::isEmpty;
 };
 
+// New class definitions for Doubly Linked List Elements and Doubly Linked Stack
+template<class T>
+class DoublyLinkedElement : public Element<T> {
+protected:
+    DoublyLinkedElement* prev;
+
+public:
+    DoublyLinkedElement() : Element<T>(), prev(nullptr) {}
+    DoublyLinkedElement(const T& data) : Element<T>(data), prev(nullptr) {}
+    DoublyLinkedElement(DoublyLinkedElement* Next, DoublyLinkedElement* Prev, const T& data)
+        : Element<T>(Next, data), prev(Prev) {}
+
+    DoublyLinkedElement* getPrev() const {
+        return prev;
+    }
+
+    void setPrev(DoublyLinkedElement* prevElement) {
+        prev = prevElement;
+    }
+};
+
+template<class T>
+class DoublyLinkedStack : public SinglyLinkedListStack<T> {
+public:
+    DoublyLinkedStack() : SinglyLinkedListStack<T>() {}
+
+    virtual Element<T>* push(const T& value) override {
+        DoublyLinkedElement<T>* newElement = new DoublyLinkedElement<T>(value);
+        if (this->head == nullptr) {
+            this->head = this->tail = newElement;
+        }
+        else {
+            static_cast<DoublyLinkedElement<T>*>(this->tail)->setNext(newElement);
+            newElement->setPrev(static_cast<DoublyLinkedElement<T>*>(this->tail));
+            this->tail = newElement;
+        }
+        this->count++;
+        return newElement;
+    }
+
+    virtual Element<T>* pop() override {
+        if (this->tail == nullptr)
+            return nullptr;
+
+        DoublyLinkedElement<T>* res = static_cast<DoublyLinkedElement<T>*>(this->tail);
+
+        if (this->head == this->tail) {
+            this->head = this->tail = nullptr;
+        }
+        else {
+            this->tail = res->getPrev();
+            this->tail->setNext(nullptr);
+        }
+
+        this->count--;
+        return res;
+    }
+
+    virtual ~DoublyLinkedStack() { cout << "\nDoublyLinkedStack class destructor\n"; }
+};
+
 int main() {
     StackQueue<int> stackQueue;
 
@@ -180,5 +241,20 @@ int main() {
     }
     cout << endl;
 
+    // Testing DoublyLinkedStack
+    DoublyLinkedStack<int> doublyLinkedStack;
+    doublyLinkedStack.push(10);
+    doublyLinkedStack.push(20);
+    doublyLinkedStack.push(30);
+
+    while (!doublyLinkedStack.isEmpty()) {
+        Element<int>* elem = doublyLinkedStack.pop();
+        if (elem) {
+            cout << elem->getInfo() << " ";
+            delete elem;
+        }
+    }
+    cout << endl;
+
     return 0;
 }