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GNAT.HTable.Simple_HTable Example

-- GNAT.HTable.Simple_HTable Example
--
-- Example of how to create a String To Object map
-- Also see GNAT.Spitbol.Table

with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;

with GNAT.IO; use GNAT.IO;
with GNAT.HTable; use GNAT.HTable;

procedure Hash is

   subtype Inches is Positive  range 1 .. 144;

   type Object is
      record
         ID     : Natural;
         Height : Inches := 1;
      end record;

   Null_Object : constant Object := (ID => 0, Height => 1);

   subtype Map_Range is Positive range 1..255;

   function String_Hash is new Hash (Map_Range);

   function Unbounded_String_Hash(F : Unbounded_String) return Map_Range is
   begin
      return String_Hash(To_String(F));
   end Unbounded_String_Hash;

   function String_Equal(F1, F2 : Unbounded_String) return Boolean is
   begin
      return F1=F2;
   end String_Equal;


   package String_To_Obj_Map is new Simple_HTable (Header_Num => Map_Range,
                                                   Element => Object,
                                                   No_Element => Null_Object,
                                                   Key => Unbounded_String,
                                                   Hash => Unbounded_String_Hash,
                                                   Equal => String_Equal);
   Current_Object : Object;
begin
   String_To_Obj_Map.Set(To_Unbounded_String("Bob"),
                         (ID => 401, Height=> 65));
   String_To_Obj_Map.Set(To_Unbounded_String("Sue"),
                         (ID => 123, Height=> 62));
   String_To_Obj_Map.Set(To_Unbounded_String("Marvin"),
                         (ID => 321, Height=> 76));
   String_To_Obj_Map.Set(To_Unbounded_String("George"),
                         (ID => 555, Height=> 68));

   Current_Object := String_To_Obj_Map.Get_First;
   while Current_Object /= Null_Object loop
      Put_Line("ID =" & Natural'Image(Current_Object.ID));
      Put_Line("Height =" & Inches'Image(Current_Object.Height));

      Current_Object := String_To_Obj_Map.Get_Next;
   end loop;

   Put_Line("Bob's height is" &
     Inches'Image(String_To_Obj_Map.Get(To_Unbounded_String("Bob")).Height));

end Hash;


(c) 1998-2004 All Rights Reserved David Botton