-- File: LookAhead.adb
--	Add the ASCII values on each line of text. 
--	Output the results, line by line, and an overall total at the end.
--	Demo of:
--	 Look ahead functionality
--	 file access
--	 Character input
--	 End of line (EOLN)
--	 Output of enumerated elements
--
-- Note: Text file must end with carriage return for this to work

with Ada.Text_Io;	use Ada;
with Ada.Integer_Text_IO;
with OpenFile;		use OpenFile;

procedure LookAhead is

   type Char_Type is (Alpha, Num, Op, Blank, X);

   package Class_IO is new Ada.Text_IO.Enumeration_IO(Char_Type);
   use Class_IO;

   Class : 			      Char_Type;
   InFile,OutFile,EnumFile: 	Text_IO.File_Type;
   Char: 			      Character;
   Sumline,Total:             Integer;
   EOL:                       Boolean;   

begin
   OpenReadFile(InFile);		-- Get file to process
   Text_IO.put("Totals Destination:"); Text_IO.New_Line;
   OpenWriteFile(OutFile);		-- Get file for numeric results
   Text_IO.put("Enum Values Destination:"); Text_IO.New_Line;
   Openwritefile(Enumfile);		-- Get file for numeric results
   Total:=0;
   while not Text_Io.End_Of_File (Infile) loop  
   -- Note: Text file must end with CR for this to work
      SumLine:=0;
      while not Text_Io.End_Of_Line (Infile) loop
         
         Text_Io.Look_Ahead(Infile,Char,Eol);
         if Eol then
            Text_Io.Put(" EOL");
         else
            Text_Io.Put("Next:"); Text_Io.Put(Char);
         End if;
         Text_IO.Get (File=>InFile, Item=>Char);
	 Text_IO.Put(Char);

         case Char is
            when 'A' .. 'Z' | 'a' .. 'z' =>            
               Class := Alpha;
            when '0' .. '9' =>                         
               Class := Num;
            when '*' | '+' | '-' | '/' | '<' .. '>' => 
               Class := Op;
            when ' ' =>
               Class:=Blank;
            when others =>                             
               Class := X;
         end case;
         SumLine:=SumLine+Character'Pos(Char);
         Class_IO.Put(Enumfile,Class); Text_Io.Put(Enumfile,' ');     -- output to enum file; 
            -- why Text_IO in one only? Is Class_IO necessary?
      end loop;
      Integer_Text_IO.put(OutFile,SumLine);
      Text_IO.New_Line (Outfile);        -- Move pointer in OutFile to new line
      Text_IO.Skip_Line (InFile);  -- Move pointer in input buffer past EOL
      Text_IO.New_Line;
      Text_IO.New_Line (Enumfile);        -- Move pointer in EnumFile to new line
      Total:=Total+SumLine;   
   end loop;
   Integer_Text_IO.Put(OutFile,Total);
   Text_IO.New_Line (Outfile);        
   Text_IO.Close(Infile);
   Text_IO.Close(Outfile);
   Text_IO.Close(EnumFile);
end LookAhead;