// LinkedListOne.h

// revised 10 sep 04 tom bailey
// printed the list elements; add op<< for standard C++ printing

// revised  23 feb 04  tom bailey
// The methods are insert and remove from the front, return
//   whether empty, and write the list elements.

// tom bailey   18 sep 02
// Declare a LinkedList class.

#pragma once

#include <iostream>
using std::ostream;

#include "node.h"


class LinkedList
{
public:
	// Post: this LinkedList is an empty NULL-terminated
	//       linked list.
	LinkedList();

	// Post: all the Nodes of this LinkedList have 
	//       been deallocated.  This LinkedList is
	//       an empty NULL-terminated linked list.
	~LinkedList();

	// Post: x has been added to the beginning of this 
	//       LinkedList.
	void insertAsFirst( double x );

	// Pre:  this LinkedList is not empty;
	// Post: the entry in the first node of this LinkedList
	//         has been returned.  The first node has been
	//         removed from this LinkedList.
	double removeFirst();

	// Post: if this LinkedList is empty, true has been
	//         returned; otherwise, false has been
	//         returned.
	bool empty() const;

	// Post: the values in this LinkedList have been
	//       written to outfile.
	void print( ostream & outfile ) const;

	// Helper methods
	// The helper methods accept a pointer to the rest of
	//   the list in place of the calling instance pointer,
	//   this.  In the helper methods, all the pointers,
	//   both start in LinkedList and link in Node, can be
	//   treated in the same way.
	// The helper methods are static, they do not have a
	//   calling instance.
protected:  
	// Pre:  ptr points to a NULL-terminated linked
	//       list.
	// Post: x has been added to the beginning of 
	//       the list.
	static void insertAsFirst( Node * & ptr, double x );

	// Pre:  ptr points to a non-empty NULL-terminated 
	//       linked list.
	// Post: the first element of the list has been
	//       removed.
	static double removeFirst( Node * & ptr );

	// Data members
protected:
	// Since start is protected, client code has no
	// access to the data stored in this LinkedList,
	// even though struct Node is very public.
	Node * start;

};

// Post: list has been written to outfile
ostream & operator<< ( ostream & outfile, const LinkedList &list);