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------------------------------------------------------------------------------
--                                                                          --
--                         GNAT LIBRARY COMPONENTS                          --
--                                                                          --
--   A D A . C O N T A I N E R S . F O R M A L _ O R D E R E D _ S E T S    --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 2010-2011, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
------------------------------------------------------------------------------
 
with Ada.Containers.Red_Black_Trees.Generic_Bounded_Operations;
pragma Elaborate_All
  (Ada.Containers.Red_Black_Trees.Generic_Bounded_Operations);
 
with Ada.Containers.Red_Black_Trees.Generic_Bounded_Keys;
pragma Elaborate_All (Ada.Containers.Red_Black_Trees.Generic_Bounded_Keys);
 
with Ada.Containers.Red_Black_Trees.Generic_Bounded_Set_Operations;
pragma Elaborate_All
  (Ada.Containers.Red_Black_Trees.Generic_Bounded_Set_Operations);
 
with System;  use type System.Address;
 
package body Ada.Containers.Formal_Ordered_Sets is
 
   ------------------------------
   -- Access to Fields of Node --
   ------------------------------
 
   --  These subprograms provide functional notation for access to fields
   --  of a node, and procedural notation for modifiying these fields.
 
   function Color (Node : Node_Type) return Red_Black_Trees.Color_Type;
   pragma Inline (Color);
 
   function Left_Son (Node : Node_Type) return Count_Type;
   pragma Inline (Left);
 
   function Parent (Node : Node_Type) return Count_Type;
   pragma Inline (Parent);
 
   function Right_Son (Node : Node_Type) return Count_Type;
   pragma Inline (Right);
 
   procedure Set_Color
     (Node  : in out Node_Type;
      Color : Red_Black_Trees.Color_Type);
   pragma Inline (Set_Color);
 
   procedure Set_Left (Node : in out Node_Type; Left : Count_Type);
   pragma Inline (Set_Left);
 
   procedure Set_Right (Node : in out Node_Type; Right : Count_Type);
   pragma Inline (Set_Right);
 
   procedure Set_Parent (Node : in out Node_Type; Parent : Count_Type);
   pragma Inline (Set_Parent);
 
   -----------------------
   -- Local Subprograms --
   -----------------------
 
   --  Comments needed???
 
   generic
      with procedure Set_Element (Node : in out Node_Type);
   procedure Generic_Allocate
     (Tree : in out Tree_Types.Tree_Type'Class;
      Node : out Count_Type);
 
   procedure Free (Tree : in out Set; X : Count_Type);
 
   procedure Insert_Sans_Hint
     (Container : in out Set;
      New_Item  : Element_Type;
      Node      : out Count_Type;
      Inserted  : out Boolean);
 
   procedure Insert_With_Hint
     (Dst_Set  : in out Set;
      Dst_Hint : Count_Type;
      Src_Node : Node_Type;
      Dst_Node : out Count_Type);
 
   function Is_Greater_Element_Node
     (Left  : Element_Type;
      Right : Node_Type) return Boolean;
   pragma Inline (Is_Greater_Element_Node);
 
   function Is_Less_Element_Node
     (Left  : Element_Type;
      Right : Node_Type) return Boolean;
   pragma Inline (Is_Less_Element_Node);
 
   function Is_Less_Node_Node (L, R : Node_Type) return Boolean;
   pragma Inline (Is_Less_Node_Node);
 
   procedure Replace_Element
     (Tree : in out Set;
      Node : Count_Type;
      Item : Element_Type);
 
   --------------------------
   -- Local Instantiations --
   --------------------------
 
   package Tree_Operations is
     new Red_Black_Trees.Generic_Bounded_Operations
       (Tree_Types,
        Left  => Left_Son,
        Right => Right_Son);
 
   use Tree_Operations;
 
   package Element_Keys is
     new Red_Black_Trees.Generic_Bounded_Keys
       (Tree_Operations     => Tree_Operations,
        Key_Type            => Element_Type,
        Is_Less_Key_Node    => Is_Less_Element_Node,
        Is_Greater_Key_Node => Is_Greater_Element_Node);
 
   package Set_Ops is
     new Red_Black_Trees.Generic_Bounded_Set_Operations
       (Tree_Operations  => Tree_Operations,
        Set_Type         => Set,
        Assign           => Assign,
        Insert_With_Hint => Insert_With_Hint,
        Is_Less          => Is_Less_Node_Node);
 
   ---------
   -- "=" --
   ---------
 
   function "=" (Left, Right : Set) return Boolean is
      Lst   : Count_Type;
      Node  : Count_Type;
      ENode : Count_Type;
 
   begin
      if Length (Left) /= Length (Right) then
         return False;
      end if;
 
      if Is_Empty (Left) then
         return True;
      end if;
 
      Lst := Next (Left, Last (Left).Node);
 
      Node := First (Left).Node;
      while Node /= Lst loop
         ENode := Find (Right, Left.Nodes (Node).Element).Node;
         if ENode = 0
           or else Left.Nodes (Node).Element /= Right.Nodes (ENode).Element
         then
            return False;
         end if;
 
         Node := Next (Left, Node);
      end loop;
 
      return True;
   end "=";
 
   ------------
   -- Assign --
   ------------
 
   procedure Assign (Target : in out Set; Source : Set) is
      procedure Append_Element (Source_Node : Count_Type);
 
      procedure Append_Elements is
        new Tree_Operations.Generic_Iteration (Append_Element);
 
      --------------------
      -- Append_Element --
      --------------------
 
      procedure Append_Element (Source_Node : Count_Type) is
         SN : Node_Type renames Source.Nodes (Source_Node);
 
         procedure Set_Element (Node : in out Node_Type);
         pragma Inline (Set_Element);
 
         function New_Node return Count_Type;
         pragma Inline (New_Node);
 
         procedure Insert_Post is
           new Element_Keys.Generic_Insert_Post (New_Node);
 
         procedure Unconditional_Insert_Sans_Hint is
           new Element_Keys.Generic_Unconditional_Insert (Insert_Post);
 
         procedure Unconditional_Insert_Avec_Hint is
           new Element_Keys.Generic_Unconditional_Insert_With_Hint
                 (Insert_Post,
                  Unconditional_Insert_Sans_Hint);
 
         procedure Allocate is new Generic_Allocate (Set_Element);
 
         --------------
         -- New_Node --
         --------------
 
         function New_Node return Count_Type is
            Result : Count_Type;
         begin
            Allocate (Target, Result);
            return Result;
         end New_Node;
 
         -----------------
         -- Set_Element --
         -----------------
 
         procedure Set_Element (Node : in out Node_Type) is
         begin
            Node.Element := SN.Element;
         end Set_Element;
 
         --  Local variables
 
         Target_Node : Count_Type;
 
      --  Start of processing for Append_Element
 
      begin
         Unconditional_Insert_Avec_Hint
           (Tree  => Target,
            Hint  => 0,
            Key   => SN.Element,
            Node  => Target_Node);
      end Append_Element;
 
      --  Start of processing for Assign
 
   begin
      if Target'Address = Source'Address then
         return;
      end if;
 
      if Target.Capacity < Source.Length then
         raise Constraint_Error
           with "Target capacity is less than Source length";
      end if;
 
      Tree_Operations.Clear_Tree (Target);
      Append_Elements (Source);
   end Assign;
 
   -------------
   -- Ceiling --
   -------------
 
   function Ceiling (Container : Set; Item : Element_Type) return Cursor is
      Node : constant Count_Type := Element_Keys.Ceiling (Container, Item);
 
   begin
      if Node = 0 then
         return No_Element;
      end if;
 
      return (Node => Node);
   end Ceiling;
 
   -----------
   -- Clear --
   -----------
 
   procedure Clear (Container : in out Set) is
   begin
      Tree_Operations.Clear_Tree (Container);
   end Clear;
 
   -----------
   -- Color --
   -----------
 
   function Color (Node : Node_Type) return Red_Black_Trees.Color_Type is
   begin
      return Node.Color;
   end Color;
 
   --------------
   -- Contains --
   --------------
 
   function Contains
     (Container : Set;
      Item      : Element_Type) return Boolean
   is
   begin
      return Find (Container, Item) /= No_Element;
   end Contains;
 
   ----------
   -- Copy --
   ----------
 
   function Copy (Source : Set; Capacity : Count_Type := 0) return Set is
      Node   : Count_Type;
      N      : Count_Type;
      Target : Set (Count_Type'Max (Source.Capacity, Capacity));
 
   begin
      if Length (Source) > 0 then
         Target.Length := Source.Length;
         Target.Root   := Source.Root;
         Target.First  := Source.First;
         Target.Last   := Source.Last;
         Target.Free   := Source.Free;
 
         Node := 1;
         while Node <= Source.Capacity loop
            Target.Nodes (Node).Element :=
              Source.Nodes (Node).Element;
            Target.Nodes (Node).Parent :=
              Source.Nodes (Node).Parent;
            Target.Nodes (Node).Left :=
              Source.Nodes (Node).Left;
            Target.Nodes (Node).Right :=
              Source.Nodes (Node).Right;
            Target.Nodes (Node).Color :=
              Source.Nodes (Node).Color;
            Target.Nodes (Node).Has_Element :=
              Source.Nodes (Node).Has_Element;
            Node := Node + 1;
         end loop;
 
         while Node <= Target.Capacity loop
            N := Node;
            Formal_Ordered_Sets.Free (Tree => Target, X => N);
            Node := Node + 1;
         end loop;
      end if;
 
      return Target;
   end Copy;
 
   ------------
   -- Delete --
   ------------
 
   procedure Delete (Container : in out Set; Position : in out Cursor) is
   begin
      if not Has_Element (Container, Position) then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      pragma Assert (Vet (Container, Position.Node),
                     "bad cursor in Delete");
 
      Tree_Operations.Delete_Node_Sans_Free (Container,
                                             Position.Node);
      Formal_Ordered_Sets.Free (Container, Position.Node);
      Position := No_Element;
   end Delete;
 
   procedure Delete (Container : in out Set; Item : Element_Type) is
      X : constant Count_Type := Element_Keys.Find (Container, Item);
 
   begin
      if X = 0 then
         raise Constraint_Error with "attempt to delete element not in set";
      end if;
 
      Tree_Operations.Delete_Node_Sans_Free (Container, X);
      Formal_Ordered_Sets.Free (Container, X);
   end Delete;
 
   ------------------
   -- Delete_First --
   ------------------
 
   procedure Delete_First (Container : in out Set) is
      X    : constant Count_Type := Container.First;
   begin
      if X /= 0 then
         Tree_Operations.Delete_Node_Sans_Free (Container, X);
         Formal_Ordered_Sets.Free (Container, X);
      end if;
   end Delete_First;
 
   -----------------
   -- Delete_Last --
   -----------------
 
   procedure Delete_Last (Container : in out Set) is
      X    : constant Count_Type := Container.Last;
   begin
      if X /= 0 then
         Tree_Operations.Delete_Node_Sans_Free (Container, X);
         Formal_Ordered_Sets.Free (Container, X);
      end if;
   end Delete_Last;
 
   ----------------
   -- Difference --
   ----------------
 
   procedure Difference (Target : in out Set; Source : Set) is
   begin
      Set_Ops.Set_Difference (Target, Source);
   end Difference;
 
   function Difference (Left, Right : Set) return Set is
   begin
      if Left'Address = Right'Address then
         return Empty_Set;
      end if;
 
      if Length (Left) = 0 then
         return Empty_Set;
      end if;
 
      if Length (Right) = 0 then
         return Left.Copy;
      end if;
 
      return S : Set (Length (Left)) do
            Assign (S, Set_Ops.Set_Difference (Left, Right));
      end return;
   end Difference;
 
   -------------
   -- Element --
   -------------
 
   function Element (Container : Set; Position : Cursor) return Element_Type is
   begin
      if not Has_Element (Container, Position) then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      pragma Assert (Vet (Container, Position.Node),
                     "bad cursor in Element");
 
      return Container.Nodes (Position.Node).Element;
   end Element;
 
   -------------------------
   -- Equivalent_Elements --
   -------------------------
 
   function Equivalent_Elements (Left, Right : Element_Type) return Boolean is
   begin
      if Left < Right
        or else Right < Left
      then
         return False;
      else
         return True;
      end if;
   end Equivalent_Elements;
 
   ---------------------
   -- Equivalent_Sets --
   ---------------------
 
   function Equivalent_Sets (Left, Right : Set) return Boolean is
      function Is_Equivalent_Node_Node
        (L, R : Node_Type) return Boolean;
      pragma Inline (Is_Equivalent_Node_Node);
 
      function Is_Equivalent is
        new Tree_Operations.Generic_Equal (Is_Equivalent_Node_Node);
 
      -----------------------------
      -- Is_Equivalent_Node_Node --
      -----------------------------
 
      function Is_Equivalent_Node_Node (L, R : Node_Type) return Boolean is
      begin
         if L.Element < R.Element then
            return False;
         elsif R.Element < L.Element then
            return False;
         else
            return True;
         end if;
      end Is_Equivalent_Node_Node;
 
   --  Start of processing for Equivalent_Sets
 
   begin
      return Is_Equivalent (Left, Right);
   end Equivalent_Sets;
 
   -------------
   -- Exclude --
   -------------
 
   procedure Exclude (Container : in out Set; Item : Element_Type) is
      X : constant Count_Type := Element_Keys.Find (Container, Item);
   begin
      if X /= 0 then
         Tree_Operations.Delete_Node_Sans_Free (Container, X);
         Formal_Ordered_Sets.Free (Container, X);
      end if;
   end Exclude;
 
   ----------
   -- Find --
   ----------
 
   function Find (Container : Set; Item : Element_Type) return Cursor is
      Node : constant Count_Type := Element_Keys.Find (Container, Item);
 
   begin
      if Node = 0 then
         return No_Element;
      end if;
 
      return (Node => Node);
   end Find;
 
   -----------
   -- First --
   -----------
 
   function First (Container : Set) return Cursor is
   begin
      if Length (Container) = 0 then
         return No_Element;
      end if;
 
      return (Node => Container.First);
   end First;
 
   -------------------
   -- First_Element --
   -------------------
 
   function First_Element (Container : Set) return Element_Type is
      Fst : constant Count_Type :=  First (Container).Node;
   begin
      if Fst = 0 then
         raise Constraint_Error with "set is empty";
      end if;
 
      declare
         N : Tree_Types.Nodes_Type renames Container.Nodes;
      begin
         return N (Fst).Element;
      end;
   end First_Element;
 
   -----------
   -- Floor --
   -----------
 
   function Floor (Container : Set; Item : Element_Type) return Cursor is
   begin
      declare
         Node : constant Count_Type := Element_Keys.Floor (Container, Item);
 
      begin
         if Node = 0 then
            return No_Element;
         end if;
 
         return (Node => Node);
      end;
   end Floor;
 
   ----------
   -- Free --
   ----------
 
   procedure Free (Tree : in out Set; X : Count_Type) is
   begin
      Tree.Nodes (X).Has_Element := False;
      Tree_Operations.Free (Tree, X);
   end Free;
 
   ----------------------
   -- Generic_Allocate --
   ----------------------
 
   procedure Generic_Allocate
     (Tree : in out Tree_Types.Tree_Type'Class;
      Node : out Count_Type)
   is
      procedure Allocate is
        new Tree_Operations.Generic_Allocate (Set_Element);
   begin
      Allocate (Tree, Node);
      Tree.Nodes (Node).Has_Element := True;
   end Generic_Allocate;
 
   ------------------
   -- Generic_Keys --
   ------------------
 
   package body Generic_Keys is
 
      -----------------------
      -- Local Subprograms --
      -----------------------
 
      function Is_Greater_Key_Node
        (Left  : Key_Type;
         Right : Node_Type) return Boolean;
      pragma Inline (Is_Greater_Key_Node);
 
      function Is_Less_Key_Node
        (Left  : Key_Type;
         Right : Node_Type) return Boolean;
      pragma Inline (Is_Less_Key_Node);
 
      --------------------------
      -- Local Instantiations --
      --------------------------
 
      package Key_Keys is
        new Red_Black_Trees.Generic_Bounded_Keys
          (Tree_Operations     => Tree_Operations,
           Key_Type            => Key_Type,
           Is_Less_Key_Node    => Is_Less_Key_Node,
           Is_Greater_Key_Node => Is_Greater_Key_Node);
 
      -------------
      -- Ceiling --
      -------------
 
      function Ceiling (Container : Set; Key : Key_Type) return Cursor is
         Node : constant Count_Type := Key_Keys.Ceiling (Container, Key);
 
      begin
         if Node = 0 then
            return No_Element;
         end if;
 
         return (Node => Node);
      end Ceiling;
 
      --------------
      -- Contains --
      --------------
 
      function Contains (Container : Set; Key : Key_Type) return Boolean is
      begin
         return Find (Container, Key) /= No_Element;
      end Contains;
 
      ------------
      -- Delete --
      ------------
 
      procedure Delete (Container : in out Set; Key : Key_Type) is
         X : constant Count_Type := Key_Keys.Find (Container, Key);
 
      begin
         if X = 0 then
            raise Constraint_Error with "attempt to delete key not in set";
         end if;
 
         Delete_Node_Sans_Free (Container, X);
         Formal_Ordered_Sets.Free (Container, X);
      end Delete;
 
      -------------
      -- Element --
      -------------
 
      function Element (Container : Set; Key : Key_Type) return Element_Type is
         Node : constant Count_Type := Key_Keys.Find (Container, Key);
 
      begin
         if Node = 0 then
            raise Constraint_Error with "key not in set";
         end if;
 
         declare
            N : Tree_Types.Nodes_Type renames Container.Nodes;
         begin
            return N (Node).Element;
         end;
      end Element;
 
      ---------------------
      -- Equivalent_Keys --
      ---------------------
 
      function Equivalent_Keys (Left, Right : Key_Type) return Boolean is
      begin
         if Left < Right
           or else Right < Left
         then
            return False;
         else
            return True;
         end if;
      end Equivalent_Keys;
 
      -------------
      -- Exclude --
      -------------
 
      procedure Exclude (Container : in out Set; Key : Key_Type) is
         X : constant Count_Type := Key_Keys.Find (Container, Key);
      begin
         if X /= 0 then
            Delete_Node_Sans_Free (Container, X);
            Formal_Ordered_Sets.Free (Container, X);
         end if;
      end Exclude;
 
      ----------
      -- Find --
      ----------
 
      function Find (Container : Set; Key : Key_Type) return Cursor is
         Node : constant Count_Type := Key_Keys.Find (Container, Key);
      begin
         return (if Node = 0 then No_Element else (Node => Node));
      end Find;
 
      -----------
      -- Floor --
      -----------
 
      function Floor (Container : Set; Key : Key_Type) return Cursor is
         Node : constant Count_Type := Key_Keys.Floor (Container, Key);
      begin
         return (if Node = 0 then No_Element else (Node => Node));
      end Floor;
 
      -------------------------
      -- Is_Greater_Key_Node --
      -------------------------
 
      function Is_Greater_Key_Node
        (Left  : Key_Type;
         Right : Node_Type) return Boolean
      is
      begin
         return Key (Right.Element) < Left;
      end Is_Greater_Key_Node;
 
      ----------------------
      -- Is_Less_Key_Node --
      ----------------------
 
      function Is_Less_Key_Node
        (Left  : Key_Type;
         Right : Node_Type) return Boolean
      is
      begin
         return Left < Key (Right.Element);
      end Is_Less_Key_Node;
 
      ---------
      -- Key --
      ---------
 
      function Key (Container : Set; Position : Cursor) return Key_Type is
      begin
         if not Has_Element (Container, Position) then
            raise Constraint_Error with
              "Position cursor has no element";
         end if;
 
         pragma Assert (Vet (Container, Position.Node),
                        "bad cursor in Key");
 
         declare
            N : Tree_Types.Nodes_Type renames Container.Nodes;
         begin
            return Key (N (Position.Node).Element);
         end;
      end Key;
 
      -------------
      -- Replace --
      -------------
 
      procedure Replace
        (Container : in out Set;
         Key       : Key_Type;
         New_Item  : Element_Type)
      is
         Node : constant Count_Type := Key_Keys.Find (Container, Key);
      begin
         if not Has_Element (Container, (Node => Node)) then
            raise Constraint_Error with
              "attempt to replace key not in set";
         else
            Replace_Element (Container, Node, New_Item);
         end if;
      end Replace;
 
      -----------------------------------
      -- Update_Element_Preserving_Key --
      -----------------------------------
 
      procedure Update_Element_Preserving_Key
        (Container : in out Set;
         Position  : Cursor;
         Process   : not null access procedure (Element : in out Element_Type))
      is
      begin
         if not Has_Element (Container, Position) then
            raise Constraint_Error with
              "Position cursor has no element";
         end if;
 
         pragma Assert (Vet (Container, Position.Node),
                        "bad cursor in Update_Element_Preserving_Key");
 
         declare
            N : Tree_Types.Nodes_Type renames Container.Nodes;
 
            E : Element_Type renames N (Position.Node).Element;
            K : constant Key_Type := Key (E);
 
            B : Natural renames Container.Busy;
            L : Natural renames Container.Lock;
 
         begin
            B := B + 1;
            L := L + 1;
 
            begin
               Process (E);
            exception
               when others =>
                  L := L - 1;
                  B := B - 1;
                  raise;
            end;
 
            L := L - 1;
            B := B - 1;
 
            if Equivalent_Keys (K, Key (E)) then
               return;
            end if;
         end;
 
         declare
            X : constant Count_Type := Position.Node;
         begin
            Tree_Operations.Delete_Node_Sans_Free (Container, X);
            Formal_Ordered_Sets.Free (Container, X);
         end;
 
         raise Program_Error with "key was modified";
      end Update_Element_Preserving_Key;
 
   end Generic_Keys;
 
   -----------------
   -- Has_Element --
   -----------------
 
   function Has_Element (Container : Set; Position : Cursor) return Boolean is
   begin
      if Position.Node = 0 then
         return False;
      else
         return Container.Nodes (Position.Node).Has_Element;
      end if;
   end Has_Element;
 
   -------------
   -- Include --
   -------------
 
   procedure Include (Container : in out Set; New_Item : Element_Type) is
      Position : Cursor;
      Inserted : Boolean;
 
   begin
      Insert (Container, New_Item, Position, Inserted);
 
      if not Inserted then
         if Container.Lock > 0 then
            raise Program_Error with
              "attempt to tamper with cursors (set is locked)";
         end if;
 
         declare
            N : Tree_Types.Nodes_Type renames Container.Nodes;
         begin
            N (Position.Node).Element := New_Item;
         end;
      end if;
   end Include;
 
   ------------
   -- Insert --
   ------------
 
   procedure Insert
     (Container : in out Set;
      New_Item  : Element_Type;
      Position  : out Cursor;
      Inserted  : out Boolean)
   is
   begin
      Insert_Sans_Hint (Container, New_Item, Position.Node, Inserted);
   end Insert;
 
   procedure Insert
     (Container : in out Set;
      New_Item  : Element_Type)
   is
      Position : Cursor;
      Inserted : Boolean;
 
   begin
      Insert (Container, New_Item, Position, Inserted);
 
      if not Inserted then
         raise Constraint_Error with
           "attempt to insert element already in set";
      end if;
   end Insert;
 
   ----------------------
   -- Insert_Sans_Hint --
   ----------------------
 
   procedure Insert_Sans_Hint
     (Container : in out Set;
      New_Item  : Element_Type;
      Node      : out Count_Type;
      Inserted  : out Boolean)
   is
      procedure Set_Element (Node : in out Node_Type);
 
      function New_Node return Count_Type;
      pragma Inline (New_Node);
 
      procedure Insert_Post is
        new Element_Keys.Generic_Insert_Post (New_Node);
 
      procedure Conditional_Insert_Sans_Hint is
        new Element_Keys.Generic_Conditional_Insert (Insert_Post);
 
      procedure Allocate is new Generic_Allocate (Set_Element);
 
      --------------
      -- New_Node --
      --------------
 
      function New_Node return Count_Type is
         Result : Count_Type;
      begin
         Allocate (Container, Result);
         return Result;
      end New_Node;
 
      -----------------
      -- Set_Element --
      -----------------
 
      procedure Set_Element (Node : in out Node_Type) is
      begin
         Node.Element := New_Item;
      end Set_Element;
 
   --  Start of processing for Insert_Sans_Hint
 
   begin
      Conditional_Insert_Sans_Hint
        (Container,
         New_Item,
         Node,
         Inserted);
   end Insert_Sans_Hint;
 
   ----------------------
   -- Insert_With_Hint --
   ----------------------
 
   procedure Insert_With_Hint
     (Dst_Set  : in out Set;
      Dst_Hint : Count_Type;
      Src_Node : Node_Type;
      Dst_Node : out Count_Type)
   is
      Success : Boolean;
      pragma Unreferenced (Success);
 
      procedure Set_Element (Node : in out Node_Type);
 
      function New_Node return Count_Type;
      pragma Inline (New_Node);
 
      procedure Insert_Post is
        new Element_Keys.Generic_Insert_Post (New_Node);
 
      procedure Insert_Sans_Hint is
        new Element_Keys.Generic_Conditional_Insert (Insert_Post);
 
      procedure Local_Insert_With_Hint is
        new Element_Keys.Generic_Conditional_Insert_With_Hint
              (Insert_Post, Insert_Sans_Hint);
 
      procedure Allocate is new Generic_Allocate (Set_Element);
 
      --------------
      -- New_Node --
      --------------
 
      function New_Node return Count_Type is
         Result : Count_Type;
      begin
         Allocate (Dst_Set, Result);
         return Result;
      end New_Node;
 
      -----------------
      -- Set_Element --
      -----------------
 
      procedure Set_Element (Node : in out Node_Type) is
      begin
         Node.Element := Src_Node.Element;
      end Set_Element;
 
   --  Start of processing for Insert_With_Hint
 
   begin
      Local_Insert_With_Hint
        (Dst_Set,
         Dst_Hint,
         Src_Node.Element,
         Dst_Node,
         Success);
   end Insert_With_Hint;
 
   ------------------
   -- Intersection --
   ------------------
 
   procedure Intersection (Target : in out Set; Source : Set) is
   begin
      Set_Ops.Set_Intersection (Target, Source);
   end Intersection;
 
   function Intersection (Left, Right : Set) return Set is
   begin
      if Left'Address = Right'Address then
         return Left.Copy;
      end if;
 
      return S : Set (Count_Type'Min (Length (Left), Length (Right))) do
            Assign (S, Set_Ops.Set_Intersection (Left, Right));
      end return;
   end Intersection;
 
   --------------
   -- Is_Empty --
   --------------
 
   function Is_Empty (Container : Set) return Boolean is
   begin
      return Length (Container) = 0;
   end Is_Empty;
 
   -----------------------------
   -- Is_Greater_Element_Node --
   -----------------------------
 
   function Is_Greater_Element_Node
     (Left  : Element_Type;
      Right : Node_Type) return Boolean
   is
   begin
      --  Compute e > node same as node < e
 
      return Right.Element < Left;
   end Is_Greater_Element_Node;
 
   --------------------------
   -- Is_Less_Element_Node --
   --------------------------
 
   function Is_Less_Element_Node
     (Left  : Element_Type;
      Right : Node_Type) return Boolean
   is
   begin
      return Left < Right.Element;
   end Is_Less_Element_Node;
 
   -----------------------
   -- Is_Less_Node_Node --
   -----------------------
 
   function Is_Less_Node_Node (L, R : Node_Type) return Boolean is
   begin
      return L.Element < R.Element;
   end Is_Less_Node_Node;
 
   ---------------
   -- Is_Subset --
   ---------------
 
   function Is_Subset (Subset : Set; Of_Set : Set) return Boolean is
   begin
      return Set_Ops.Set_Subset (Subset, Of_Set => Of_Set);
   end Is_Subset;
 
   -------------
   -- Iterate --
   -------------
 
   procedure Iterate
     (Container : Set;
      Process   : not null access procedure (Container : Set;
                                             Position : Cursor))
   is
      procedure Process_Node (Node : Count_Type);
      pragma Inline (Process_Node);
 
      procedure Local_Iterate is
        new Tree_Operations.Generic_Iteration (Process_Node);
 
      ------------------
      -- Process_Node --
      ------------------
 
      procedure Process_Node (Node : Count_Type) is
      begin
         Process (Container, (Node => Node));
      end Process_Node;
 
      --  Local variables
 
      B : Natural renames Container'Unrestricted_Access.Busy;
 
   --  Start of prccessing for Iterate
 
   begin
      B := B + 1;
 
      begin
         Local_Iterate (Container);
      exception
         when others =>
            B := B - 1;
            raise;
      end;
 
      B := B - 1;
   end Iterate;
 
   ----------
   -- Last --
   ----------
 
   function Last (Container : Set) return Cursor is
   begin
      return (if Length (Container) = 0
              then No_Element
              else (Node => Container.Last));
   end Last;
 
   ------------------
   -- Last_Element --
   ------------------
 
   function Last_Element (Container : Set) return Element_Type is
   begin
      if Last (Container).Node = 0 then
         raise Constraint_Error with "set is empty";
      end if;
 
      declare
         N : Tree_Types.Nodes_Type renames Container.Nodes;
      begin
         return N (Last (Container).Node).Element;
      end;
   end Last_Element;
 
   ----------
   -- Left --
   ----------
 
   function Left (Container : Set; Position : Cursor) return Set is
      Curs : Cursor := Position;
      C    : Set (Container.Capacity) := Copy (Container, Container.Capacity);
      Node : Count_Type;
 
   begin
      if Curs = No_Element then
         return C;
      end if;
 
      if not Has_Element (Container, Curs) then
         raise Constraint_Error;
      end if;
 
      while Curs.Node /= 0 loop
         Node := Curs.Node;
         Delete (C, Curs);
         Curs := Next (Container, (Node => Node));
      end loop;
 
      return C;
   end Left;
 
   --------------
   -- Left_Son --
   --------------
 
   function Left_Son (Node : Node_Type) return Count_Type is
   begin
      return Node.Left;
   end Left_Son;
 
   ------------
   -- Length --
   ------------
 
   function Length (Container : Set) return Count_Type is
   begin
      return Container.Length;
   end Length;
 
   ----------
   -- Move --
   ----------
 
   procedure Move (Target : in out Set; Source : in out Set) is
      N : Tree_Types.Nodes_Type renames Source.Nodes;
      X : Count_Type;
 
   begin
      if Target'Address = Source'Address then
         return;
      end if;
 
      if Target.Capacity < Length (Source) then
         raise Constraint_Error with  -- ???
           "Source length exceeds Target capacity";
      end if;
 
      if Source.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with cursors of Source (list is busy)";
      end if;
 
      Clear (Target);
 
      loop
         X := Source.First;
         exit when X = 0;
 
         Insert (Target, N (X).Element);  -- optimize???
 
         Tree_Operations.Delete_Node_Sans_Free (Source, X);
         Formal_Ordered_Sets.Free (Source, X);
      end loop;
   end Move;
 
   ----------
   -- Next --
   ----------
 
   function Next (Container : Set; Position : Cursor) return Cursor is
   begin
      if Position = No_Element then
         return No_Element;
      end if;
 
      if not Has_Element (Container, Position) then
         raise Constraint_Error;
      end if;
 
      pragma Assert (Vet (Container, Position.Node),
                     "bad cursor in Next");
      return (Node => Tree_Operations.Next (Container, Position.Node));
   end Next;
 
   procedure Next (Container : Set; Position : in out Cursor) is
   begin
      Position := Next (Container, Position);
   end Next;
 
   -------------
   -- Overlap --
   -------------
 
   function Overlap (Left, Right : Set) return Boolean is
   begin
      return Set_Ops.Set_Overlap (Left, Right);
   end Overlap;
 
   ------------
   -- Parent --
   ------------
 
   function Parent (Node : Node_Type) return Count_Type is
   begin
      return Node.Parent;
   end Parent;
 
   --------------
   -- Previous --
   --------------
 
   function Previous (Container : Set; Position : Cursor) return Cursor is
   begin
      if Position = No_Element then
         return No_Element;
      end if;
 
      if not Has_Element (Container, Position) then
         raise Constraint_Error;
      end if;
 
      pragma Assert (Vet (Container, Position.Node),
                     "bad cursor in Previous");
 
      declare
         Node : constant Count_Type :=
                  Tree_Operations.Previous (Container, Position.Node);
      begin
         return (if Node = 0 then No_Element else (Node => Node));
      end;
   end Previous;
 
   procedure Previous (Container : Set; Position : in out Cursor) is
   begin
      Position := Previous (Container, Position);
   end Previous;
 
   -------------------
   -- Query_Element --
   -------------------
 
   procedure Query_Element
     (Container : in out Set;
      Position  : Cursor;
      Process   : not null access procedure (Element : Element_Type))
   is
   begin
      if not Has_Element (Container, Position) then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      pragma Assert (Vet (Container, Position.Node),
                     "bad cursor in Query_Element");
 
      declare
         B : Natural renames Container.Busy;
         L : Natural renames Container.Lock;
 
      begin
         B := B + 1;
         L := L + 1;
 
         begin
            Process (Container.Nodes (Position.Node).Element);
         exception
            when others =>
               L := L - 1;
               B := B - 1;
               raise;
         end;
 
         L := L - 1;
         B := B - 1;
      end;
   end Query_Element;
 
   ----------
   -- Read --
   ----------
 
   procedure Read
     (Stream    : not null access Root_Stream_Type'Class;
      Container : out Set)
   is
      procedure Read_Element (Node : in out Node_Type);
      pragma Inline (Read_Element);
 
      procedure Allocate is
        new Generic_Allocate (Read_Element);
 
      procedure Read_Elements is
        new Tree_Operations.Generic_Read (Allocate);
 
      ------------------
      -- Read_Element --
      ------------------
 
      procedure Read_Element (Node : in out Node_Type) is
      begin
         Element_Type'Read (Stream, Node.Element);
      end Read_Element;
 
   --  Start of processing for Read
 
   begin
      Read_Elements (Stream, Container);
   end Read;
 
   procedure Read
     (Stream : not null access Root_Stream_Type'Class;
      Item   : out Cursor)
   is
   begin
      raise Program_Error with "attempt to stream set cursor";
   end Read;
 
   -------------
   -- Replace --
   -------------
 
   procedure Replace (Container : in out Set; New_Item : Element_Type) is
      Node : constant Count_Type := Element_Keys.Find (Container, New_Item);
 
   begin
      if Node = 0 then
         raise Constraint_Error with
           "attempt to replace element not in set";
      end if;
 
      if Container.Lock > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (set is locked)";
      end if;
 
      Container.Nodes (Node).Element := New_Item;
   end Replace;
 
   ---------------------
   -- Replace_Element --
   ---------------------
 
   procedure Replace_Element
     (Tree : in out Set;
      Node : Count_Type;
      Item : Element_Type)
   is
      pragma Assert (Node /= 0);
 
      function New_Node return Count_Type;
      pragma Inline (New_Node);
 
      procedure Local_Insert_Post is
        new Element_Keys.Generic_Insert_Post (New_Node);
 
      procedure Local_Insert_Sans_Hint is
        new Element_Keys.Generic_Conditional_Insert (Local_Insert_Post);
 
      procedure Local_Insert_With_Hint is
        new Element_Keys.Generic_Conditional_Insert_With_Hint
          (Local_Insert_Post,
           Local_Insert_Sans_Hint);
 
      NN : Tree_Types.Nodes_Type renames Tree.Nodes;
 
      --------------
      -- New_Node --
      --------------
 
      function New_Node return Count_Type is
         N  : Node_Type renames NN (Node);
      begin
         N.Element := Item;
         N.Color   := Red;
         N.Parent  := 0;
         N.Right   := 0;
         N.Left    := 0;
         return Node;
      end New_Node;
 
      Hint      : Count_Type;
      Result    : Count_Type;
      Inserted  : Boolean;
 
   --  Start of processing for Insert
 
   begin
      if Item < NN (Node).Element
        or else NN (Node).Element < Item
      then
         null;
 
      else
         if Tree.Lock > 0 then
            raise Program_Error with
              "attempt to tamper with cursors (set is locked)";
         end if;
 
         NN (Node).Element := Item;
         return;
      end if;
 
      Hint := Element_Keys.Ceiling (Tree, Item);
 
      if Hint = 0 then
         null;
 
      elsif Item < NN (Hint).Element then
         if Hint = Node then
            if Tree.Lock > 0 then
               raise Program_Error with
                 "attempt to tamper with cursors (set is locked)";
            end if;
 
            NN (Node).Element := Item;
            return;
         end if;
 
      else
         pragma Assert (not (NN (Hint).Element < Item));
         raise Program_Error with "attempt to replace existing element";
      end if;
 
      Tree_Operations.Delete_Node_Sans_Free (Tree, Node);  -- Checks busy-bit
 
      Local_Insert_With_Hint
        (Tree     => Tree,
         Position => Hint,
         Key      => Item,
         Node     => Result,
         Inserted => Inserted);
 
      pragma Assert (Inserted);
      pragma Assert (Result = Node);
   end Replace_Element;
 
   procedure Replace_Element
     (Container : in out Set;
      Position  : Cursor;
      New_Item  : Element_Type)
   is
   begin
      if not Has_Element (Container, Position) then
         raise Constraint_Error with
           "Position cursor has no element";
      end if;
 
      pragma Assert (Vet (Container, Position.Node),
                     "bad cursor in Replace_Element");
 
      Replace_Element (Container, Position.Node, New_Item);
   end Replace_Element;
 
   ---------------------
   -- Reverse_Iterate --
   ---------------------
 
   procedure Reverse_Iterate
     (Container : Set;
      Process   : not null access procedure (Container : Set;
                                             Position : Cursor))
   is
      procedure Process_Node (Node : Count_Type);
      pragma Inline (Process_Node);
 
      procedure Local_Reverse_Iterate is
        new Tree_Operations.Generic_Reverse_Iteration (Process_Node);
 
      ------------------
      -- Process_Node --
      ------------------
 
      procedure Process_Node (Node : Count_Type) is
      begin
         Process (Container, (Node => Node));
      end Process_Node;
 
      B : Natural renames Container'Unrestricted_Access.Busy;
 
   --  Start of processing for Reverse_Iterate
 
   begin
      B := B + 1;
 
      begin
         Local_Reverse_Iterate (Container);
      exception
         when others =>
            B := B - 1;
            raise;
      end;
 
      B := B - 1;
   end Reverse_Iterate;
 
   -----------
   -- Right --
   -----------
 
   function Right (Container : Set; Position : Cursor) return Set is
      Curs : Cursor := First (Container);
      C    : Set (Container.Capacity) := Copy (Container, Container.Capacity);
      Node : Count_Type;
 
   begin
      if Curs = No_Element then
         Clear (C);
         return C;
      end if;
 
      if Position /= No_Element and not Has_Element (Container, Position) then
         raise Constraint_Error;
      end if;
 
      while Curs.Node /= Position.Node loop
         Node := Curs.Node;
         Delete (C, Curs);
         Curs := Next (Container, (Node => Node));
      end loop;
 
      return C;
   end Right;
 
   ---------------
   -- Right_Son --
   ---------------
 
   function Right_Son (Node : Node_Type) return Count_Type is
   begin
      return Node.Right;
   end Right_Son;
 
   ---------------
   -- Set_Color --
   ---------------
 
   procedure Set_Color
     (Node  : in out Node_Type;
      Color : Red_Black_Trees.Color_Type)
   is
   begin
      Node.Color := Color;
   end Set_Color;
 
   --------------
   -- Set_Left --
   --------------
 
   procedure Set_Left (Node : in out Node_Type; Left : Count_Type) is
   begin
      Node.Left := Left;
   end Set_Left;
 
   ----------------
   -- Set_Parent --
   ----------------
 
   procedure Set_Parent (Node : in out Node_Type; Parent : Count_Type) is
   begin
      Node.Parent := Parent;
   end Set_Parent;
 
   ---------------
   -- Set_Right --
   ---------------
 
   procedure Set_Right (Node : in out Node_Type; Right : Count_Type) is
   begin
      Node.Right := Right;
   end Set_Right;
 
   ------------------
   -- Strict_Equal --
   ------------------
 
   function Strict_Equal (Left, Right : Set) return Boolean is
      LNode : Count_Type := First (Left).Node;
      RNode : Count_Type := First (Right).Node;
 
   begin
      if Length (Left) /= Length (Right) then
         return False;
      end if;
 
      while LNode = RNode loop
         if LNode = 0 then
            return True;
         end if;
 
         if Left.Nodes (LNode).Element /=
           Right.Nodes (RNode).Element then
            exit;
         end if;
 
         LNode := Next (Left, LNode);
         RNode := Next (Right, RNode);
      end loop;
 
      return False;
   end Strict_Equal;
 
   --------------------------
   -- Symmetric_Difference --
   --------------------------
 
   procedure Symmetric_Difference (Target : in out Set; Source : Set) is
   begin
      Set_Ops.Set_Symmetric_Difference (Target, Source);
   end Symmetric_Difference;
 
   function Symmetric_Difference (Left, Right : Set) return Set is
   begin
      if Left'Address = Right'Address then
         return Empty_Set;
      end if;
 
      if Length (Right) = 0 then
         return Left.Copy;
      end if;
 
      if Length (Left) = 0 then
         return Right.Copy;
      end if;
 
      return S : Set (Length (Left) + Length (Right)) do
         Assign (S, Set_Ops.Set_Symmetric_Difference (Left, Right));
      end return;
   end Symmetric_Difference;
 
   ------------
   -- To_Set --
   ------------
 
   function To_Set (New_Item : Element_Type) return Set is
      Node     : Count_Type;
      Inserted : Boolean;
   begin
      return S : Set (Capacity => 1) do
         Insert_Sans_Hint (S, New_Item, Node, Inserted);
         pragma Assert (Inserted);
      end return;
   end To_Set;
 
   -----------
   -- Union --
   -----------
 
   procedure Union (Target : in out Set; Source : Set) is
   begin
      Set_Ops.Set_Union (Target, Source);
   end Union;
 
   function Union (Left, Right : Set) return Set is
   begin
      if Left'Address = Right'Address then
         return Left.Copy;
      end if;
 
      if Length (Left) = 0 then
         return Right.Copy;
      end if;
 
      if Length (Right) = 0 then
         return Left.Copy;
      end if;
 
      return S : Set (Length (Left) + Length (Right)) do
         S.Assign (Source => Left);
         S.Union (Right);
      end return;
   end Union;
 
   -----------
   -- Write --
   -----------
 
   procedure Write
     (Stream    : not null access Root_Stream_Type'Class;
      Container : Set)
   is
      procedure Write_Element
        (Stream : not null access Root_Stream_Type'Class;
         Node   : Node_Type);
      pragma Inline (Write_Element);
 
      procedure Write_Elements is
        new Tree_Operations.Generic_Write (Write_Element);
 
      -------------------
      -- Write_Element --
      -------------------
 
      procedure Write_Element
        (Stream : not null access Root_Stream_Type'Class;
         Node   : Node_Type)
      is
      begin
         Element_Type'Write (Stream, Node.Element);
      end Write_Element;
 
   --  Start of processing for Write
 
   begin
      Write_Elements (Stream, Container);
   end Write;
 
   procedure Write
     (Stream : not null access Root_Stream_Type'Class;
      Item   : Cursor)
   is
   begin
      raise Program_Error with "attempt to stream set cursor";
   end Write;
 
end Ada.Containers.Formal_Ordered_Sets;