-- This file is  free  software, which  comes  along  with  SmartEiffel. This
-- software  is  distributed  in the hope that it will be useful, but WITHOUT
-- ANY  WARRANTY;  without  even  the  implied warranty of MERCHANTABILITY or
-- FITNESS  FOR A PARTICULAR PURPOSE. You can modify it as you want, provided
-- this header is kept unaltered, and a notification of the changes is added.
-- You  are  allowed  to  redistribute  it and sell it, alone or as a part of
-- another product.
--       Copyright (C) 1994-2002 LORIA - INRIA - U.H.P. Nancy 1 - FRANCE
--          Dominique COLNET and Suzanne COLLIN - SmartEiffel@loria.fr
--                       http://SmartEiffel.loria.fr
--
expanded class SAFE_EQUAL[E]
   --
   -- The goal of this class is to share the definition of feature `safe_equal'.
   -- Feature `safe_equal' compares two arguments of type E, by calling `is_equal'
   -- only and only if both arguments have the `same_type'.
   --

feature {NONE}

   safe_equal(e1, e2: E): BOOLEAN is
         -- In order to avoid run-time type errors, feature `safe_equal' call
         -- `is_equal' only when `e1' and `e2' have exactly the same `generating_type'.
         -- Furthermore, this feature avoid argument passing from some
         -- expanded type to the corresponding reference type (no automatic
         -- allocation of some reference type during the comparison).
      do
         if e1.is_basic_expanded_type then
            Result := e1 = e2
         elseif e1.is_expanded_type then
            Result := e1.is_equal(e2)
         elseif e1 = e2 then
            Result := true
         elseif e1 = Void or else e2 = Void then
	 elseif e1.generating_type = e2.generating_type then
            Result := e1.is_equal(e2)
         end
      end

end
