For use with CMSC-341, Spring 99,  Project 2

Here is the definition of the Iterator class. 

Copy it to your Iterator.H file. 

Remember:
 -- implement the inline method(s)
 -- guard the file
 -- complete the documentation
------------------------------------------------

/*
   Generic iterator over collections.
   The base class for all iterators.
   Author: Thomas Anastasio
   Version:  6 February 1999
*/
template <class T>
class Iterator
{
private:
  // Traversal order.  See IteratorConstants class
  int _direction; 
protected:
  // Mutator for direction (traversal order)
  // Each subclass defines a default if dir is not
  // one of the constants in IteratorConstants class
  inline void SetDirection(int dir);
public:
  // Test for exhaustion of the iterator.
  // Return: true if there are more elements available
  virtual bool HasNext() = 0;

  // Accessor for the next element
  // Return: the next available element and advance
  // the iteration.
  // Precondition: It is an error to call this method when there
  // is no next element (i.e. when HasNext() is false)
  virtual T Next() = 0;

  // Accessor for the traversal order
  // Return: the traversal order.  Will be one of the
  // constants from IteratorConstants class
  inline int GetDirection();
};


// Output operator for iterators.
// Writes, to os, the elements of the underlying collection 
// of iter as a comma separated list.
// Param: os the output stream to which to write
// Param: iter is a pointer to the Iterator to be output
// Returns: os
template<class T>
ostream& operator<< (ostream & os, Iterator<T> * iter);