File : protected_sorted_index.adb


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--  $Id: protected_sorted_index.adb,v 1.5 2004/02/09 18:21:09 Jano Exp $


--  Implements a double indexed container, with sorted semantics and

--  search by id.

--  However, currently the search isn't efficient (takes O (n)).

--  It's ok for use with not huge lists.


package body Protected_sorted_index is

   use Implementation;

   protected body Sorted_index is 

      procedure Clear is
      begin
         Clear (List);
      end Clear;

      -- No duplicates (replacement)

      procedure Insert (Item : in Element_type) is
         Success : Boolean;
      begin
         Delete (Item, Success);       -- Local

         Insert (List, Item); -- Implementation

      end Insert;

      function Find (Item : in Element_type) return Iterator_type is
         I : Iterator_type := First (List);
      begin
         while I /= Back (List) loop
            if Item = Element (I) then
               return I;
            else
               I := Succ (I);
            end if;
         end loop;

         return Back (List);
      end Find;

      function Find (Item : in Element_type) return Boolean is
      begin
         return Find (Item) /= Back (List);
      end Find;

      procedure Delete (Item : in Element_type; Success : out Boolean) is
         I : Iterator_type := Find (Item); -- Local!

      begin
         Success := I /= Back (List);
         if Success then
            Delete (List, I);
         end if;
      end Delete;

      -- Blocking if empty

      -- Doesn't remove it

      entry Get_first (Item : out Element_type) when not Is_empty is
      begin
         Item := Element (First (List));
      end Get_first;

      -- Get first if possible:

      procedure Get_first (Item : out Element_type; Success : out Boolean) is
      begin
         Success := not Is_empty;
         if Success then 
            Item := Element (First (List));
         end if;
      end Get_first;

      -- Get and remove an element if found, nothing else.

      procedure Get_remove (
         Item    : in out Element_type; Found : out Boolean) is
         I       : Iterator_type;
         Success : Boolean;
      begin
         I := Find (Item); -- Local

         Found := I /= Back (List);
         if Found then
            Item := Element (I);
            Delete (Item, Success); -- Local

            if not Success then
               raise Constraint_error;
            end if;
         end if;
      end Get_remove;

      -- Get first if exists and remove it

      procedure Get_first_remove (
         Item : out Element_type; Found : out Boolean) 
      is
         Success : Boolean;
      begin
         Get_first (Item, Found);
         if Found then
            Delete (Item, Success); -- Local

            if not Success then
               raise Constraint_error;
            end if;
         end if;
      end Get_first_remove;

      function Is_empty return Boolean is
      begin
         return Is_empty (List);
      end Is_empty;

      function Length return Natural is
      begin
         return Length (List);
      end Length;

   end Sorted_index;

end Protected_sorted_index;