with ada.text_io;
   with ada.integer_text_io;
   with stack;
    procedure program4_V1 is
   
     -- need a blank line to initialize & reinitialize strings
      blank_line : CONSTANT  String(1..80) := (OTHERS => ' ');
   
      blank : CONSTANT character := ' ';
   
      infix_String : String (1..80); -- original string in infix form
      postfix_String : String (1..80); -- result string in postfix form
      last_in : integer; -- to indicate position of last character in input string
      done    : boolean := false;  -- will indicate when processing input string is complete
   
     -- instantiation of a stack to hold the characters
       package Character_Stack is new Stack (Element_Type => Character);
      myStack : Character_Stack.Stack_Type (Max_Size => 50);  -- to hold operators and parentheses from input string
   
     
      
   
   begin
      loop -- program will handle multiple strings 
      
       -- code for a single string 
       
       -- initialize strings to all blanks so as not to have any old characters in it
      
      
       
       -- prompt user for a string in infix form   
      
      
       -- get string from user
       
      
       -- echo the infix string with a label    
       
      
      
       -- initialize empty stack  
       
      
       -- while not entire string processed
         while not done loop -- while more characters in infix string -- OTHER KIND OF LOOP?
           
           
         -- get a character from the infix string
         
             
         	  -- if it's a blank ignore it
         	  
         	  
         	  
         	  -- else if it's alphabetic add it to the postfix string followed by a blank
         	  
         	  
         	  
         	  
         	  
         	  
         	  -- else if it's a left parenthesis, put it on stack
         
          
            
         	
         	
         	
         	
         	  -- else if it is a right parenthesis, pop the stack and append each of the
         	  -- OPERATORS on it, to the postfix string followed by a blank. Stop
         	  -- popping the stack after popping a left parenthesis. 
         	  
         
         
         
         
         
         
         
         
         
         	  -- else if it's an operator 
            loop -- pop operators from the stack and append them
             null;               -- to the postfix string followed by a blank UNTIL
              -- 1.  the stack is empty
              -- 2.  an operator of lower priority than the operator is found
              -- 3.  a left parenthesis is found
              -- push 2 OR 3 back to the stack followed by operator
            end loop; -- when operator pushed on stack
         	   
         end loop;  -- leave loop when no more characters in input string
      	
      	-- pop rest of stack a character at a time and append each followed 
      	-- by a blank to postfix string
      	
      	-- print the postfix string with a label
      	
      end loop; -- for line 21
   			
   	-- print ending message (i.e. Program has processed all the input data)	
   	
   end program4_V1;