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From: Martin Trenkmann <martin.trenkmann@posteo.de>
Newsgroups: comp.lang.ada
Subject: Implementing character sets for Wide_Character
Date: Fri, 06 Mar 2015 19:01:33 +0100
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Date: 2015-03-06T19:01:33+01:00
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I need to implement a containment check for Wide_Character in a wide character set. I have two approaches in mind.

1. Using an array type similar to Ada.Strings.Maps.Character_Set.

   type Wide_Character_Set is array (Wide_Character) of Boolean with Pack;
   
   XYZ_Charset_Set : constant Wide_Character_Set
     := (Wide_Character'Val (100) .. Wide_Character'Val (900) => True,
         others                                               => False);

2. Using a function with a case statement.

   function Is_In_XYZ_Charset_Set (Item : Wide_Character) return Boolean is
   begin
      case Item is
         when Wide_Character'Val (100) .. Wide_Character'Val (900) => return True;
         when others                                               => return False;
      end case;
   end Is_In_XYZ_Charset_Set;


I know that using an array will consume more memory, but with the Pack aspect it should only be 8 KB - please correct me if I am wrong. The function approach is more memory friendly, but might be a bit slower as an array lookup.

Should I definitely avoid one of the solutions or is just a matter of available memory?

Thanks for your help.

Martin