with ada.text_io;
with ada.integer_text_io;
procedure testAccessExample is
-- this program demonstrates the creation and use of pointer variables
-- it also demonstrates the creation of a 2 element linked list 
-- it then shows the list with a third element inserted at the head of the list.

type cell;  -- announcement that there will be a cell type

type link is access cell;  -- I will have something that points to a cell

type cell is  -- defines a heterogeneous type known as a record 
              -- which contains the previously defined link
				  -- note that we have a circular definition
  record
     value : integer;
	  next  : link;
  end record;
   head : link;  -- declaration of three pointers (links)
   current   : link;   
	newLink : link;
 begin
   -- initialize the first cell
	newLink := new cell;
	newLink.next := null; -- make the next field in the cell being pointed to NULL
   newLink.value := 37;  -- make the value field in the cell being pointed to 37

  	head := newLink;  -- make head point to created cell(i.e. tocell with 37)
   
   -- create another cell
	newLink := new cell;
	newLink.value := 27; -- put a value in the new link

   -- connect the two cells
	head.next := newLink; -- add the 2nd one to the end

 
   -- print the two element list with a label
    ada.text_io.put (" Here's the two element list ");
    current := head;
	while current /= null loop
	  ada.integer_text_io.put (current.value);
	  current := current.next;
	end loop; 
	ada.text_io.new_line;
	  
   -- create a third cell
	newLink := new cell;
	newLink.value := 4;

   -- insert the new node at the head of the list
	newLink.next := head; 
	head := newLink;

   -- print the list again	with a label
	ada.text_io.put (" Here's the list with the newest cell at the head ");

   -- another way to chain through the list
	current := head; -- set an extra pointer to move through the list
	ada.integer_text_io.put (current.value);
	while current.next /= null loop
	   current:= current.next;
		ada.integer_text_io.put (current.value);
	end loop;
	
end testAccessExample;