auto_wide_queue.cpp

// auto_wide_queue.cpp: auto expanding queue

#include <iostream>

using namespace std;

template <class T>
class queue //auto expanding queue
{
	class node //class which store array and pointer to next
	{
		T* node_array;
		int push_pos;
		int pop_pos;
		int array_length;
	public:
		node* next;
		node(int array_length) {
			node_array = new T[array_length];
			next = nullptr;
			this->array_length = array_length;
			push_pos = 0;
			pop_pos = 0;
		}
		~node() {
			delete[] node_array;
		}
		bool push(const T element) {
			if (push_pos < array_length) {
				node_array[push_pos] = element;
				push_pos++;
				return 1;
			}
			else {
				return 0; //if node is full
			}
		}
		bool is_empty() {
			if (push_pos - pop_pos) {
				return 0;
			}
			else {
				return 1;
			}
		}
		T pop() {
			if (this->is_empty()) { 
				return NULL;
			}
			pop_pos++;
			return node_array[pop_pos - 1];
		}
		void print() {	// class T output operator must be overloaded! (if not, comment thist function)
			cout << "*****" << endl;
			for (int i = pop_pos; i < push_pos; i++) {
				cout << node_array[i] << endl;
			}
		}
	};
	node* head;
	node* tail;
	int arr_length;
public:
	queue(int arr_length) :head(nullptr), tail(nullptr) {
		if (arr_length <= 0) {
			cout << "Error: Arr_length <= 0" << endl;
			return;
		}
		this->arr_length = arr_length;
	};
	~queue()
	{
		node *temp = head;
		while (temp != nullptr) {
			temp = head->next;
			delete head;
			head = temp;
		}
	}
	void push(T element){
		if (head != nullptr)
		{
			if (!tail->push(element)) //check space in node 
			{
				node* temp = new node(arr_length);
				temp->push(element);
				tail->next = temp;
				tail = temp;
			}
		}
		else {
			node* temp = new node(arr_length);
			temp->push(element);
			head = tail = temp;
		}
	}
	void print(){
		node* temp = head; //temporary pointer to head
		while (temp != nullptr) //while exists pointer to next
		{
			temp->print();
			temp = temp->next;
		}
	}
	T pop(){
		if (head != nullptr)
		{
			T obj = head->pop();
			if (head->is_empty()) {
				if (head == tail) {
					head = tail = nullptr;
				}
				else {
					node* temp_node = head;
					head = head->next;
					delete temp_node;
				}
			}
			return obj;
		}
		return NULL;
	}
};

int main()
{
	queue<int> q(4);

	q.push(1);
	q.push(2);
	q.push(3);
	q.push(4);
	q.push(5);
	q.push(6);

	cout << "El:" << q.pop() << endl;
	cout << "El:" << q.pop() << endl;
	cout << "El:" << q.pop() << endl;
	cout << "El:" << q.pop() << endl;
	cout << "El:" << q.pop() << endl;

	q.print();
    return 0;
}