Refactor code structure for improved readability and maintainability

demos/lists/cpp/main.cpp

@@ -0,0 +1,80 @@
+#include <iostream>
+#include <optional>
+
+// A single node containing data and a raw pointer to the next node
+template <typename T>
+struct Node {
+    T data;
+    Node<T>* next;
+};
+
+// The main wrapper for the linked list tracking the head node
+template <typename T>
+class LinkedList {
+public:
+    LinkedList() : head_(nullptr) {}
+
+    ~LinkedList() {
+        Node<T>* current = head_;
+        while (current) {
+            Node<T>* next = current->next;
+            delete current;
+            current = next;
+        }
+    }
+
+    // Raw-pointer ownership can't be safely duplicated by a shallow copy
+    LinkedList(const LinkedList&) = delete;
+    LinkedList& operator=(const LinkedList&) = delete;
+
+    // Add a new element to the front of the list
+    void push_front(T data) {
+        head_ = new Node<T>{std::move(data), head_};
+    }
+
+    // Remove and return the front element of the list
+    std::optional<T> pop_front() {
+        if (!head_) {
+            return std::nullopt;
+        }
+        Node<T>* old_head = head_;
+        T data = std::move(old_head->data);
+        head_ = old_head->next;
+        delete old_head;
+        return data;
+    }
+
+    // Read the front element without removing it
+    const T* peek_front() const {
+        return head_ ? &head_->data : nullptr;
+    }
+
+private:
+    Node<T>* head_;
+};
+
+int main() {
+    LinkedList<int> list;
+    int count=0;
+    char * message1 = "hello world";
+    // Demonstrate pushing items
+    list.push_front(10);
+    count++;
+    list.push_front(20);
+    count++;
+    list.push_front(30);
+    count++;
+
+    // Demonstrate peeking at the top item
+    if (const int* top = list.peek_front()) {
+        std::cout << "Top element: " << *top << "\n"<<"count: "<<count<<"\n"; // Output: 30
+    }
+    std::cout<<message1<<"\n";
+
+    // Demonstrate popping items
+    while (auto value = list.pop_front()) {
+        std::cout << "Popped: " << *value << "\n";
+    }
+
+    return 0;
+}