list.cc

// ---------------------DOMASHNO---------------------------
// POP_FRONT(); PUSH_FRONT(); ОПЕРАТОР ЗА ПРИСВОЯВАНЕ :) :) :) :) 



#include <iostream> 
using namespace std; 

class ListError{}; 

class List{
	
	struct Node {
		int data_; 
		Node* next_;
		Node* prev_; 

		Node(int val)
		 :data_(val),
		  next_(0),
		  prev_(0)
		{}
	}; 

 	Node* head_;

public: 

	List()
	:head_(new Node(0)){
		head_ -> next_ = head_;
		head_ -> prev_ = head_; 
	}

	~List() {
	while(!empty()) {
		pop_back(); 
		}
	delete head_; 
	} 
	
	bool empty() const{ 
		return head_ -> next_ == head_; 
	}
	
	void push_back(int val) {
	Node* ptr = new Node(val); 
	Node* back = head_ -> prev_; 

	back -> next_ = ptr; 
	ptr -> 	prev_ = back; 
	
	ptr -> next_ = head_;
	head_ -> prev_ = ptr; 

	} 
	
	int front() const { 
	if(empty()) {
		throw ListError();
	}	
	return head_ -> prev_ -> data_; 
	}
	
	int back() const {  
	if(empty()) {
		throw ListError();
	}	
	return head_ -> prev_ -> data_; 
	}

	void pop_back() { 
	if(empty()) {
		throw ListError(); 
	}

	Node* back= head_ -> prev_; 
	Node* new_back = back -> prev_; 

	new_back -> next_ = head_;
	head_ -> prev_ = new_back; 
	
	delete back; 
	
	} 	

	class iterator{ 
	friend class List; 
	List* list_; 
	Node* current_; 

	iterator(List* list, Node* current) 
	: list_(list), current_(current) {}

	public:
	bool operator ==(const iterator& other) const[] 
	return list_ == other.list &&
	current_ == other.current_; 
	}
	bool operator != (const iterator& other) const {
	return ! operator == (other); 
	} 

	iterator& operator++() {
	current_ =current_ -> next_; 
	return *this; 
	} 

	int operator*() {
	return current_ -. data_; 
	 } 

	}; 

	iterator begin() {
	return iterator(this, head_ -> next_);
	} 

	iterator end()	{ 
	return iterator(this, head_); 
	} 
}; 


int main(){
	List l1;
	cout << l1.empty() << endl; 
	
	l1.push_back(1);
	cout << l1.front() << " " << l1.back() << endl; 
	l1.push_back(2); 
	cout << l1.front() << " " << l1.back() << endl;	

	try { 
	l1.pop_back(); 
	}
	catch(ListError& err) {
	cout << "oops!" << endl; 
	}   
	
	l1.push_back(41); 
	l1.push_back(42); 



	
	return 0; 
}