The crossover operator for Genetic Algorithm

crossover.adb

function Crossover (X, Y : Array_Type; Start_Index : Index_Type) return Array_Type is
	Result : Array_Type := X;
	Start_Item : constant Element_Type := X (Start_Index);
	Index : Index_Type := Start_Index;
begin
	while Y (Index) /= Start_Item loop
		for I in X'Range loop
			if X (I) = Y (Index) then
				Result (Index) := Y (Index);
				Index := I;
				goto Found;
			end if;
		end loop;
		raise Program_Error;
		<<Found>> null;
	end loop;
	Result (Index) := Y (Index);
	return Result;
end Crossover;

crossover.ads

generic
	type Index_Type is (<>);
	type Element_Type is private;
	type Array_Type is array (Index_Type) of Element_Type;
function Crossover (X, Y : Array_Type; Start_Index : Index_Type) return Array_Type;
pragma Pure (Crossover);