-- Chapter 31 - Program 3
generic
   type ITEM is range <>;
   ROWS    : in POSITIVE := 8;
   COLUMNS : in POSITIVE := 12;
package Matrix_Operations is

   type LOCAL_MATRIX is private;

   procedure Clear_Matrix(Matrix_To_Clear : in out LOCAL_MATRIX);

   function Add_Matrices(M1, M2 : LOCAL_MATRIX) return LOCAL_MATRIX;

private
   type LOCAL_MATRIX is array(POSITIVE range 1..ROWS,
                              POSITIVE range 1..COLUMNS) of ITEM;
end Matrix_Operations;




with Ada.Text_IO;
use Ada.Text_IO;
package body Matrix_Operations is

   procedure Clear_Matrix(Matrix_To_Clear : in out LOCAL_MATRIX) is
   begin
      for Row in 1..Matrix_To_Clear'LAST(1) loop
         for column in 1.. Matrix_To_Clear'LAST(2) loop
            Matrix_To_Clear(Row,Column) := 0;
         end loop;
      end loop;
      Put_Line("  A matrix has been cleared");
   end Clear_Matrix;

   function Add_Matrices(M1, M2 : LOCAL_MATRIX) return LOCAL_MATRIX is
   Temp : LOCAL_MATRIX;
   begin
      for Row in 1..M1'LAST(1) loop
         for column in 1.. M1'LAST(2) loop
            Temp(Row, Column) := M1(Row, Column) + M2(Row, Column);
         end loop;
      end loop;
      Put_Line("  Two matrices have been summed");
      return Temp;
   end Add_Matrices;

end Matrix_Operations;




with Ada.Text_IO, Matrix_Operations;
use Ada.Text_IO;

procedure ObjGen is

package Cookie_Jar is new Matrix_Operations(NATURAL, 3, 5);
use Cookie_Jar;
package Puppies is new Matrix_Operations(INTEGER);
package Animals is new Matrix_Operations(COLUMNS => 7,
                                         ROWS => 11,
                                         ITEM => INTEGER);
use Animals;

Cookie_Matrix                : Cookie_Jar.LOCAL_MATRIX;
Dog_Matrix                   : Puppies.LOCAL_MATRIX;
Cattle, Jerseys, Black_Angus : Animals.LOCAL_MATRIX;

begin
   Put_Line("Begin the matrix operations.");
   Clear_Matrix(Cookie_Matrix);
   Puppies.Clear_Matrix(Dog_Matrix);
   Clear_Matrix(Jerseys);
   Clear_Matrix(Black_Angus);
   Cattle := Add_Matrices(Jerseys, Black_Angus);

end ObjGen;




-- Result of execution

-- Begin the matrix operations
--   A matrix has been cleared
--   A matrix has been cleared
--   A matrix has been cleared
--   A matrix has been cleared
--   Two matrices have been summed