#ifndef LIST_H_
#define LIST_H_

#include <ostream>
#include "Node.h"

class List{
public:
	// default constructor: 
        // POST: *this is an empty list
        List();  

        // destructor
	~List();

	// copy constructor
	List (const List& l);

	// assignment operator
	List& operator= (const List& l); 

	// POST: key was added before first element of *this
	void push_front(int key);

	// POST: key was added after last element of *this
	void push_back (int key);

	// POST: the first occurrence of key was removed from *this
	//       if *this does not contain key, nothing happened
	void remove (int key);

	// POST: returns const pointer to the first node
	const Node* get_head() const;

	// POST: the list was emptied
	void clear();
	
	// POST: returns the number of the elements in *this
	int size() const;
	
	// POST: all duplicates in *this are removed
	void unique();
	
	// POST: the elements of *this are in reversed order
	void reverse();
	
	// POST: a copy of l is appended to *this
	void append(const List& l);
	
	// POST: *l is appended to *this - aliasing 
	void append(const List* l);  // on sheet (copy)
	
private:
	Node* head_;
	
	// PRE: *this is empty
	// POST: list starting at from was copied to *this
	void copy (const Node* from);
};

// output operator
std::ostream& operator<< (std::ostream& o, const List& l);

#endif