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------------------------------------------------------------------------------
--                                                                          --
--                         GNAT LIBRARY COMPONENTS                          --
--                                                                          --
--                A D A . C O N T A I N E R S . V E C T O R S               --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 2004-2009, 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/>.                                          --
--                                                                          --
-- This unit was originally developed by Matthew J Heaney.                  --
------------------------------------------------------------------------------
 
with Ada.Containers.Generic_Array_Sort;
with Ada.Unchecked_Deallocation;
 
with System; use type System.Address;
 
package body Ada.Containers.Vectors is
 
   type Int is range System.Min_Int .. System.Max_Int;
   type UInt is mod System.Max_Binary_Modulus;
 
   procedure Free is
     new Ada.Unchecked_Deallocation (Elements_Type, Elements_Access);
 
   ---------
   -- "&" --
   ---------
 
   function "&" (Left, Right : Vector) return Vector is
      LN : constant Count_Type := Length (Left);
      RN : constant Count_Type := Length (Right);
 
   begin
      if LN = 0 then
         if RN = 0 then
            return Empty_Vector;
         end if;
 
         declare
            RE : Elements_Array renames
                   Right.Elements.EA (Index_Type'First .. Right.Last);
 
            Elements : constant Elements_Access :=
                         new Elements_Type'(Right.Last, RE);
 
         begin
            return (Controlled with Elements, Right.Last, 0, 0);
         end;
      end if;
 
      if RN = 0 then
         declare
            LE : Elements_Array renames
                   Left.Elements.EA (Index_Type'First .. Left.Last);
 
            Elements : constant Elements_Access :=
                         new Elements_Type'(Left.Last, LE);
 
         begin
            return (Controlled with Elements, Left.Last, 0, 0);
         end;
 
      end if;
 
      declare
         N           : constant Int'Base := Int (LN) + Int (RN);
         Last_As_Int : Int'Base;
 
      begin
         if Int (No_Index) > Int'Last - N then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         Last_As_Int := Int (No_Index) + N;
 
         if Last_As_Int > Int (Index_Type'Last) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         declare
            Last : constant Index_Type := Index_Type (Last_As_Int);
 
            LE : Elements_Array renames
                   Left.Elements.EA (Index_Type'First .. Left.Last);
 
            RE : Elements_Array renames
                   Right.Elements.EA (Index_Type'First .. Right.Last);
 
            Elements : constant Elements_Access :=
                         new Elements_Type'(Last, LE & RE);
 
         begin
            return (Controlled with Elements, Last, 0, 0);
         end;
      end;
   end "&";
 
   function "&" (Left  : Vector; Right : Element_Type) return Vector is
      LN : constant Count_Type := Length (Left);
 
   begin
      if LN = 0 then
         declare
            Elements : constant Elements_Access :=
                         new Elements_Type'
                               (Last => Index_Type'First,
                                EA   => (others => Right));
 
         begin
            return (Controlled with Elements, Index_Type'First, 0, 0);
         end;
      end if;
 
      declare
         Last_As_Int : Int'Base;
 
      begin
         if Int (Index_Type'First) > Int'Last - Int (LN) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         Last_As_Int := Int (Index_Type'First) + Int (LN);
 
         if Last_As_Int > Int (Index_Type'Last) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         declare
            Last : constant Index_Type := Index_Type (Last_As_Int);
 
            LE : Elements_Array renames
                   Left.Elements.EA (Index_Type'First .. Left.Last);
 
            Elements : constant Elements_Access :=
                         new Elements_Type'
                               (Last => Last,
                                EA   => LE & Right);
 
         begin
            return (Controlled with Elements, Last, 0, 0);
         end;
      end;
   end "&";
 
   function "&" (Left  : Element_Type; Right : Vector) return Vector is
      RN : constant Count_Type := Length (Right);
 
   begin
      if RN = 0 then
         declare
            Elements : constant Elements_Access :=
                         new Elements_Type'
                               (Last => Index_Type'First,
                                EA   => (others => Left));
 
         begin
            return (Controlled with Elements, Index_Type'First, 0, 0);
         end;
      end if;
 
      declare
         Last_As_Int : Int'Base;
 
      begin
         if Int (Index_Type'First) > Int'Last - Int (RN) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         Last_As_Int := Int (Index_Type'First) + Int (RN);
 
         if Last_As_Int > Int (Index_Type'Last) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         declare
            Last : constant Index_Type := Index_Type (Last_As_Int);
 
            RE : Elements_Array renames
                   Right.Elements.EA (Index_Type'First .. Right.Last);
 
            Elements : constant Elements_Access :=
                         new Elements_Type'
                               (Last => Last,
                                EA   => Left & RE);
 
         begin
            return (Controlled with Elements, Last, 0, 0);
         end;
      end;
   end "&";
 
   function "&" (Left, Right : Element_Type) return Vector is
   begin
      if Index_Type'First >= Index_Type'Last then
         raise Constraint_Error with "new length is out of range";
      end if;
 
      declare
         Last : constant Index_Type := Index_Type'First + 1;
 
         Elements : constant Elements_Access :=
                      new Elements_Type'
                            (Last => Last,
                             EA   => (Left, Right));
 
      begin
         return (Controlled with Elements, Last, 0, 0);
      end;
   end "&";
 
   ---------
   -- "=" --
   ---------
 
   overriding function "=" (Left, Right : Vector) return Boolean is
   begin
      if Left'Address = Right'Address then
         return True;
      end if;
 
      if Left.Last /= Right.Last then
         return False;
      end if;
 
      for J in Index_Type range Index_Type'First .. Left.Last loop
         if Left.Elements.EA (J) /= Right.Elements.EA (J) then
            return False;
         end if;
      end loop;
 
      return True;
   end "=";
 
   ------------
   -- Adjust --
   ------------
 
   procedure Adjust (Container : in out Vector) is
   begin
      if Container.Last = No_Index then
         Container.Elements := null;
         return;
      end if;
 
      declare
         L  : constant Index_Type := Container.Last;
         EA : Elements_Array renames
                Container.Elements.EA (Index_Type'First .. L);
 
      begin
         Container.Elements := null;
         Container.Busy := 0;
         Container.Lock := 0;
 
         --  Note: it may seem that the following assignment to Container.Last
         --  is useless, since we assign it to L below. However this code is
         --  used in case 'new Elements_Type' below raises an exception, to
         --  keep Container in a consistent state.
 
         Container.Last := No_Index;
         Container.Elements := new Elements_Type'(L, EA);
         Container.Last := L;
      end;
   end Adjust;
 
   ------------
   -- Append --
   ------------
 
   procedure Append (Container : in out Vector; New_Item : Vector) is
   begin
      if Is_Empty (New_Item) then
         return;
      end if;
 
      if Container.Last = Index_Type'Last then
         raise Constraint_Error with "vector is already at its maximum length";
      end if;
 
      Insert
        (Container,
         Container.Last + 1,
         New_Item);
   end Append;
 
   procedure Append
     (Container : in out Vector;
      New_Item  : Element_Type;
      Count     : Count_Type := 1)
   is
   begin
      if Count = 0 then
         return;
      end if;
 
      if Container.Last = Index_Type'Last then
         raise Constraint_Error with "vector is already at its maximum length";
      end if;
 
      Insert
        (Container,
         Container.Last + 1,
         New_Item,
         Count);
   end Append;
 
   --------------
   -- Capacity --
   --------------
 
   function Capacity (Container : Vector) return Count_Type is
   begin
      if Container.Elements = null then
         return 0;
      end if;
 
      return Container.Elements.EA'Length;
   end Capacity;
 
   -----------
   -- Clear --
   -----------
 
   procedure Clear (Container : in out Vector) is
   begin
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      Container.Last := No_Index;
   end Clear;
 
   --------------
   -- Contains --
   --------------
 
   function Contains
     (Container : Vector;
      Item      : Element_Type) return Boolean
   is
   begin
      return Find_Index (Container, Item) /= No_Index;
   end Contains;
 
   ------------
   -- Delete --
   ------------
 
   procedure Delete
     (Container : in out Vector;
      Index     : Extended_Index;
      Count     : Count_Type := 1)
   is
   begin
      if Index < Index_Type'First then
         raise Constraint_Error with "Index is out of range (too small)";
      end if;
 
      if Index > Container.Last then
         if Index > Container.Last + 1 then
            raise Constraint_Error with "Index is out of range (too large)";
         end if;
 
         return;
      end if;
 
      if Count = 0 then
         return;
      end if;
 
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      declare
         I_As_Int        : constant Int := Int (Index);
         Old_Last_As_Int : constant Int := Index_Type'Pos (Container.Last);
 
         Count1 : constant Int'Base := Count_Type'Pos (Count);
         Count2 : constant Int'Base := Old_Last_As_Int - I_As_Int + 1;
         N      : constant Int'Base := Int'Min (Count1, Count2);
 
         J_As_Int : constant Int'Base := I_As_Int + N;
 
      begin
         if J_As_Int > Old_Last_As_Int then
            Container.Last := Index - 1;
 
         else
            declare
               J  : constant Index_Type := Index_Type (J_As_Int);
               EA : Elements_Array renames Container.Elements.EA;
 
               New_Last_As_Int : constant Int'Base := Old_Last_As_Int - N;
               New_Last        : constant Index_Type :=
                                   Index_Type (New_Last_As_Int);
 
            begin
               EA (Index .. New_Last) := EA (J .. Container.Last);
               Container.Last := New_Last;
            end;
         end if;
      end;
   end Delete;
 
   procedure Delete
     (Container : in out Vector;
      Position  : in out Cursor;
      Count     : Count_Type := 1)
   is
      pragma Warnings (Off, Position);
 
   begin
      if Position.Container = null then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      if Position.Container /= Container'Unrestricted_Access then
         raise Program_Error with "Position cursor denotes wrong container";
      end if;
 
      if Position.Index > Container.Last then
         raise Program_Error with "Position index is out of range";
      end if;
 
      Delete (Container, Position.Index, Count);
      Position := No_Element;
   end Delete;
 
   ------------------
   -- Delete_First --
   ------------------
 
   procedure Delete_First
     (Container : in out Vector;
      Count     : Count_Type := 1)
   is
   begin
      if Count = 0 then
         return;
      end if;
 
      if Count >= Length (Container) then
         Clear (Container);
         return;
      end if;
 
      Delete (Container, Index_Type'First, Count);
   end Delete_First;
 
   -----------------
   -- Delete_Last --
   -----------------
 
   procedure Delete_Last
     (Container : in out Vector;
      Count     : Count_Type := 1)
   is
      Index : Int'Base;
 
   begin
      if Count = 0 then
         return;
      end if;
 
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      Index := Int'Base (Container.Last) - Int'Base (Count);
 
      Container.Last :=
         (if Index < Index_Type'Pos (Index_Type'First)
          then No_Index
          else Index_Type (Index));
   end Delete_Last;
 
   -------------
   -- Element --
   -------------
 
   function Element
     (Container : Vector;
      Index     : Index_Type) return Element_Type
   is
   begin
      if Index > Container.Last then
         raise Constraint_Error with "Index is out of range";
      end if;
 
      return Container.Elements.EA (Index);
   end Element;
 
   function Element (Position : Cursor) return Element_Type is
   begin
      if Position.Container = null then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      if Position.Index > Position.Container.Last then
         raise Constraint_Error with "Position cursor is out of range";
      end if;
 
      return Position.Container.Elements.EA (Position.Index);
   end Element;
 
   --------------
   -- Finalize --
   --------------
 
   procedure Finalize (Container : in out Vector) is
      X : Elements_Access := Container.Elements;
 
   begin
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      Container.Elements := null;
      Container.Last := No_Index;
      Free (X);
   end Finalize;
 
   ----------
   -- Find --
   ----------
 
   function Find
     (Container : Vector;
      Item      : Element_Type;
      Position  : Cursor := No_Element) return Cursor
   is
   begin
      if Position.Container /= null then
         if Position.Container /= Container'Unrestricted_Access then
            raise Program_Error with "Position cursor denotes wrong container";
         end if;
 
         if Position.Index > Container.Last then
            raise Program_Error with "Position index is out of range";
         end if;
      end if;
 
      for J in Position.Index .. Container.Last loop
         if Container.Elements.EA (J) = Item then
            return (Container'Unchecked_Access, J);
         end if;
      end loop;
 
      return No_Element;
   end Find;
 
   ----------------
   -- Find_Index --
   ----------------
 
   function Find_Index
     (Container : Vector;
      Item      : Element_Type;
      Index     : Index_Type := Index_Type'First) return Extended_Index
   is
   begin
      for Indx in Index .. Container.Last loop
         if Container.Elements.EA (Indx) = Item then
            return Indx;
         end if;
      end loop;
 
      return No_Index;
   end Find_Index;
 
   -----------
   -- First --
   -----------
 
   function First (Container : Vector) return Cursor is
   begin
      if Is_Empty (Container) then
         return No_Element;
      end if;
 
      return (Container'Unchecked_Access, Index_Type'First);
   end First;
 
   -------------------
   -- First_Element --
   -------------------
 
   function First_Element (Container : Vector) return Element_Type is
   begin
      if Container.Last = No_Index then
         raise Constraint_Error with "Container is empty";
      end if;
 
      return Container.Elements.EA (Index_Type'First);
   end First_Element;
 
   -----------------
   -- First_Index --
   -----------------
 
   function First_Index (Container : Vector) return Index_Type is
      pragma Unreferenced (Container);
   begin
      return Index_Type'First;
   end First_Index;
 
   ---------------------
   -- Generic_Sorting --
   ---------------------
 
   package body Generic_Sorting is
 
      ---------------
      -- Is_Sorted --
      ---------------
 
      function Is_Sorted (Container : Vector) return Boolean is
      begin
         if Container.Last <= Index_Type'First then
            return True;
         end if;
 
         declare
            EA : Elements_Array renames Container.Elements.EA;
         begin
            for I in Index_Type'First .. Container.Last - 1 loop
               if EA (I + 1) < EA (I) then
                  return False;
               end if;
            end loop;
         end;
 
         return True;
      end Is_Sorted;
 
      -----------
      -- Merge --
      -----------
 
      procedure Merge (Target, Source : in out Vector) is
         I : Index_Type'Base := Target.Last;
         J : Index_Type'Base;
 
      begin
         if Target.Last < Index_Type'First then
            Move (Target => Target, Source => Source);
            return;
         end if;
 
         if Target'Address = Source'Address then
            return;
         end if;
 
         if Source.Last < Index_Type'First then
            return;
         end if;
 
         if Source.Busy > 0 then
            raise Program_Error with
              "attempt to tamper with elements (vector is busy)";
         end if;
 
         Target.Set_Length (Length (Target) + Length (Source));
 
         declare
            TA : Elements_Array renames Target.Elements.EA;
            SA : Elements_Array renames Source.Elements.EA;
 
         begin
            J := Target.Last;
            while Source.Last >= Index_Type'First loop
               pragma Assert (Source.Last <= Index_Type'First
                                or else not (SA (Source.Last) <
                                             SA (Source.Last - 1)));
 
               if I < Index_Type'First then
                  TA (Index_Type'First .. J) :=
                    SA (Index_Type'First .. Source.Last);
 
                  Source.Last := No_Index;
                  return;
               end if;
 
               pragma Assert (I <= Index_Type'First
                                or else not (TA (I) < TA (I - 1)));
 
               if SA (Source.Last) < TA (I) then
                  TA (J) := TA (I);
                  I := I - 1;
 
               else
                  TA (J) := SA (Source.Last);
                  Source.Last := Source.Last - 1;
               end if;
 
               J := J - 1;
            end loop;
         end;
      end Merge;
 
      ----------
      -- Sort --
      ----------
 
      procedure Sort (Container : in out Vector)
      is
         procedure Sort is
            new Generic_Array_Sort
             (Index_Type   => Index_Type,
              Element_Type => Element_Type,
              Array_Type   => Elements_Array,
              "<"          => "<");
 
      begin
         if Container.Last <= Index_Type'First then
            return;
         end if;
 
         if Container.Lock > 0 then
            raise Program_Error with
              "attempt to tamper with cursors (vector is locked)";
         end if;
 
         Sort (Container.Elements.EA (Index_Type'First .. Container.Last));
      end Sort;
 
   end Generic_Sorting;
 
   -----------------
   -- Has_Element --
   -----------------
 
   function Has_Element (Position : Cursor) return Boolean is
   begin
      if Position.Container = null then
         return False;
      end if;
 
      return Position.Index <= Position.Container.Last;
   end Has_Element;
 
   ------------
   -- Insert --
   ------------
 
   procedure Insert
     (Container : in out Vector;
      Before    : Extended_Index;
      New_Item  : Element_Type;
      Count     : Count_Type := 1)
   is
      N : constant Int := Count_Type'Pos (Count);
 
      First           : constant Int := Int (Index_Type'First);
      New_Last_As_Int : Int'Base;
      New_Last        : Index_Type;
      New_Length      : UInt;
      Max_Length      : constant UInt := UInt (Count_Type'Last);
 
      Dst : Elements_Access;
 
   begin
      if Before < Index_Type'First then
         raise Constraint_Error with
           "Before index is out of range (too small)";
      end if;
 
      if Before > Container.Last
        and then Before > Container.Last + 1
      then
         raise Constraint_Error with
           "Before index is out of range (too large)";
      end if;
 
      if Count = 0 then
         return;
      end if;
 
      declare
         Old_Last_As_Int : constant Int := Int (Container.Last);
 
      begin
         if Old_Last_As_Int > Int'Last - N then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         New_Last_As_Int := Old_Last_As_Int + N;
 
         if New_Last_As_Int > Int (Index_Type'Last) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         New_Length := UInt (New_Last_As_Int - First + Int'(1));
 
         if New_Length > Max_Length then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         New_Last := Index_Type (New_Last_As_Int);
      end;
 
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      if Container.Elements = null then
         Container.Elements := new Elements_Type'
                                     (Last => New_Last,
                                      EA   => (others => New_Item));
         Container.Last := New_Last;
         return;
      end if;
 
      if New_Last <= Container.Elements.Last then
         declare
            EA : Elements_Array renames Container.Elements.EA;
 
         begin
            if Before <= Container.Last then
               declare
                  Index_As_Int : constant Int'Base :=
                                   Index_Type'Pos (Before) + N;
 
                  Index : constant Index_Type := Index_Type (Index_As_Int);
 
               begin
                  EA (Index .. New_Last) := EA (Before .. Container.Last);
 
                  EA (Before .. Index_Type'Pred (Index)) :=
                      (others => New_Item);
               end;
 
            else
               EA (Before .. New_Last) := (others => New_Item);
            end if;
         end;
 
         Container.Last := New_Last;
         return;
      end if;
 
      declare
         C, CC : UInt;
 
      begin
         C := UInt'Max (1, Container.Elements.EA'Length);  -- ???
         while C < New_Length loop
            if C > UInt'Last / 2 then
               C := UInt'Last;
               exit;
            end if;
 
            C := 2 * C;
         end loop;
 
         if C > Max_Length then
            C := Max_Length;
         end if;
 
         if Index_Type'First <= 0
           and then Index_Type'Last >= 0
         then
            CC := UInt (Index_Type'Last) + UInt (-Index_Type'First) + 1;
         else
            CC := UInt (Int (Index_Type'Last) - First + 1);
         end if;
 
         if C > CC then
            C := CC;
         end if;
 
         declare
            Dst_Last : constant Index_Type :=
                         Index_Type (First + UInt'Pos (C) - 1);
 
         begin
            Dst := new Elements_Type (Dst_Last);
         end;
      end;
 
      declare
         SA : Elements_Array renames Container.Elements.EA;
         DA : Elements_Array renames Dst.EA;
 
      begin
         DA (Index_Type'First .. Index_Type'Pred (Before)) :=
           SA (Index_Type'First .. Index_Type'Pred (Before));
 
         if Before <= Container.Last then
            declare
               Index_As_Int : constant Int'Base :=
                                Index_Type'Pos (Before) + N;
 
               Index : constant Index_Type := Index_Type (Index_As_Int);
 
            begin
               DA (Before .. Index_Type'Pred (Index)) := (others => New_Item);
               DA (Index .. New_Last) := SA (Before .. Container.Last);
            end;
 
         else
            DA (Before .. New_Last) := (others => New_Item);
         end if;
      exception
         when others =>
            Free (Dst);
            raise;
      end;
 
      declare
         X : Elements_Access := Container.Elements;
      begin
         Container.Elements := Dst;
         Container.Last := New_Last;
         Free (X);
      end;
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Extended_Index;
      New_Item  : Vector)
   is
      N : constant Count_Type := Length (New_Item);
 
   begin
      if Before < Index_Type'First then
         raise Constraint_Error with
           "Before index is out of range (too small)";
      end if;
 
      if Before > Container.Last
        and then Before > Container.Last + 1
      then
         raise Constraint_Error with
           "Before index is out of range (too large)";
      end if;
 
      if N = 0 then
         return;
      end if;
 
      Insert_Space (Container, Before, Count => N);
 
      declare
         Dst_Last_As_Int : constant Int'Base :=
                             Int'Base (Before) + Int'Base (N) - 1;
 
         Dst_Last : constant Index_Type := Index_Type (Dst_Last_As_Int);
 
      begin
         if Container'Address /= New_Item'Address then
            Container.Elements.EA (Before .. Dst_Last) :=
              New_Item.Elements.EA (Index_Type'First .. New_Item.Last);
 
            return;
         end if;
 
         declare
            subtype Src_Index_Subtype is Index_Type'Base range
              Index_Type'First .. Before - 1;
 
            Src : Elements_Array renames
                    Container.Elements.EA (Src_Index_Subtype);
 
            Index_As_Int : constant Int'Base :=
                             Int (Before) + Src'Length - 1;
 
            Index : constant Index_Type'Base :=
                      Index_Type'Base (Index_As_Int);
 
            Dst : Elements_Array renames
                    Container.Elements.EA (Before .. Index);
 
         begin
            Dst := Src;
         end;
 
         if Dst_Last = Container.Last then
            return;
         end if;
 
         declare
            subtype Src_Index_Subtype is Index_Type'Base range
              Dst_Last + 1 .. Container.Last;
 
            Src : Elements_Array renames
                    Container.Elements.EA (Src_Index_Subtype);
 
            Index_As_Int : constant Int'Base :=
                             Dst_Last_As_Int - Src'Length + 1;
 
            Index : constant Index_Type :=
                      Index_Type (Index_As_Int);
 
            Dst : Elements_Array renames
                    Container.Elements.EA (Index .. Dst_Last);
 
         begin
            Dst := Src;
         end;
      end;
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Cursor;
      New_Item  : Vector)
   is
      Index : Index_Type'Base;
 
   begin
      if Before.Container /= null
        and then Before.Container /= Container'Unchecked_Access
      then
         raise Program_Error with "Before cursor denotes wrong container";
      end if;
 
      if Is_Empty (New_Item) then
         return;
      end if;
 
      if Before.Container = null
        or else Before.Index > Container.Last
      then
         if Container.Last = Index_Type'Last then
            raise Constraint_Error with
              "vector is already at its maximum length";
         end if;
 
         Index := Container.Last + 1;
 
      else
         Index := Before.Index;
      end if;
 
      Insert (Container, Index, New_Item);
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Cursor;
      New_Item  : Vector;
      Position  : out Cursor)
   is
      Index : Index_Type'Base;
 
   begin
      if Before.Container /= null
        and then Before.Container /= Container'Unchecked_Access
      then
         raise Program_Error with "Before cursor denotes wrong container";
      end if;
 
      if Is_Empty (New_Item) then
         if Before.Container = null
           or else Before.Index > Container.Last
         then
            Position := No_Element;
         else
            Position := (Container'Unchecked_Access, Before.Index);
         end if;
 
         return;
      end if;
 
      if Before.Container = null
        or else Before.Index > Container.Last
      then
         if Container.Last = Index_Type'Last then
            raise Constraint_Error with
              "vector is already at its maximum length";
         end if;
 
         Index := Container.Last + 1;
 
      else
         Index := Before.Index;
      end if;
 
      Insert (Container, Index, New_Item);
 
      Position := Cursor'(Container'Unchecked_Access, Index);
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Cursor;
      New_Item  : Element_Type;
      Count     : Count_Type := 1)
   is
      Index : Index_Type'Base;
 
   begin
      if Before.Container /= null
        and then Before.Container /= Container'Unchecked_Access
      then
         raise Program_Error with "Before cursor denotes wrong container";
      end if;
 
      if Count = 0 then
         return;
      end if;
 
      if Before.Container = null
        or else Before.Index > Container.Last
      then
         if Container.Last = Index_Type'Last then
            raise Constraint_Error with
              "vector is already at its maximum length";
         end if;
 
         Index := Container.Last + 1;
 
      else
         Index := Before.Index;
      end if;
 
      Insert (Container, Index, New_Item, Count);
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Cursor;
      New_Item  : Element_Type;
      Position  : out Cursor;
      Count     : Count_Type := 1)
   is
      Index : Index_Type'Base;
 
   begin
      if Before.Container /= null
        and then Before.Container /= Container'Unchecked_Access
      then
         raise Program_Error with "Before cursor denotes wrong container";
      end if;
 
      if Count = 0 then
         if Before.Container = null
           or else Before.Index > Container.Last
         then
            Position := No_Element;
         else
            Position := (Container'Unchecked_Access, Before.Index);
         end if;
 
         return;
      end if;
 
      if Before.Container = null
        or else Before.Index > Container.Last
      then
         if Container.Last = Index_Type'Last then
            raise Constraint_Error with
              "vector is already at its maximum length";
         end if;
 
         Index := Container.Last + 1;
 
      else
         Index := Before.Index;
      end if;
 
      Insert (Container, Index, New_Item, Count);
 
      Position := Cursor'(Container'Unchecked_Access, Index);
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Extended_Index;
      Count     : Count_Type := 1)
   is
      New_Item : Element_Type;  -- Default-initialized value
      pragma Warnings (Off, New_Item);
 
   begin
      Insert (Container, Before, New_Item, Count);
   end Insert;
 
   procedure Insert
     (Container : in out Vector;
      Before    : Cursor;
      Position  : out Cursor;
      Count     : Count_Type := 1)
   is
      New_Item : Element_Type;  -- Default-initialized value
      pragma Warnings (Off, New_Item);
 
   begin
      Insert (Container, Before, New_Item, Position, Count);
   end Insert;
 
   ------------------
   -- Insert_Space --
   ------------------
 
   procedure Insert_Space
     (Container : in out Vector;
      Before    : Extended_Index;
      Count     : Count_Type := 1)
   is
      N : constant Int := Count_Type'Pos (Count);
 
      First           : constant Int := Int (Index_Type'First);
      New_Last_As_Int : Int'Base;
      New_Last        : Index_Type;
      New_Length      : UInt;
      Max_Length      : constant UInt := UInt (Count_Type'Last);
 
      Dst : Elements_Access;
 
   begin
      if Before < Index_Type'First then
         raise Constraint_Error with
           "Before index is out of range (too small)";
      end if;
 
      if Before > Container.Last
        and then Before > Container.Last + 1
      then
         raise Constraint_Error with
           "Before index is out of range (too large)";
      end if;
 
      if Count = 0 then
         return;
      end if;
 
      declare
         Old_Last_As_Int : constant Int := Int (Container.Last);
 
      begin
         if Old_Last_As_Int > Int'Last - N then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         New_Last_As_Int := Old_Last_As_Int + N;
 
         if New_Last_As_Int > Int (Index_Type'Last) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         New_Length := UInt (New_Last_As_Int - First + Int'(1));
 
         if New_Length > Max_Length then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         New_Last := Index_Type (New_Last_As_Int);
      end;
 
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      if Container.Elements = null then
         Container.Elements := new Elements_Type (New_Last);
         Container.Last := New_Last;
         return;
      end if;
 
      if New_Last <= Container.Elements.Last then
         declare
            EA : Elements_Array renames Container.Elements.EA;
         begin
            if Before <= Container.Last then
               declare
                  Index_As_Int : constant Int'Base :=
                                   Index_Type'Pos (Before) + N;
 
                  Index : constant Index_Type := Index_Type (Index_As_Int);
 
               begin
                  EA (Index .. New_Last) := EA (Before .. Container.Last);
               end;
            end if;
         end;
 
         Container.Last := New_Last;
         return;
      end if;
 
      declare
         C, CC : UInt;
 
      begin
         C := UInt'Max (1, Container.Elements.EA'Length);  -- ???
         while C < New_Length loop
            if C > UInt'Last / 2 then
               C := UInt'Last;
               exit;
            end if;
 
            C := 2 * C;
         end loop;
 
         if C > Max_Length then
            C := Max_Length;
         end if;
 
         if Index_Type'First <= 0
           and then Index_Type'Last >= 0
         then
            CC := UInt (Index_Type'Last) + UInt (-Index_Type'First) + 1;
         else
            CC := UInt (Int (Index_Type'Last) - First + 1);
         end if;
 
         if C > CC then
            C := CC;
         end if;
 
         declare
            Dst_Last : constant Index_Type :=
                         Index_Type (First + UInt'Pos (C) - 1);
 
         begin
            Dst := new Elements_Type (Dst_Last);
         end;
      end;
 
      declare
         SA : Elements_Array renames Container.Elements.EA;
         DA : Elements_Array renames Dst.EA;
 
      begin
         DA (Index_Type'First .. Index_Type'Pred (Before)) :=
           SA (Index_Type'First .. Index_Type'Pred (Before));
 
         if Before <= Container.Last then
            declare
               Index_As_Int : constant Int'Base :=
                                Index_Type'Pos (Before) + N;
 
               Index : constant Index_Type := Index_Type (Index_As_Int);
 
            begin
               DA (Index .. New_Last) := SA (Before .. Container.Last);
            end;
         end if;
      exception
         when others =>
            Free (Dst);
            raise;
      end;
 
      declare
         X : Elements_Access := Container.Elements;
      begin
         Container.Elements := Dst;
         Container.Last := New_Last;
         Free (X);
      end;
   end Insert_Space;
 
   procedure Insert_Space
     (Container : in out Vector;
      Before    : Cursor;
      Position  : out Cursor;
      Count     : Count_Type := 1)
   is
      Index : Index_Type'Base;
 
   begin
      if Before.Container /= null
        and then Before.Container /= Container'Unchecked_Access
      then
         raise Program_Error with "Before cursor denotes wrong container";
      end if;
 
      if Count = 0 then
         if Before.Container = null
           or else Before.Index > Container.Last
         then
            Position := No_Element;
         else
            Position := (Container'Unchecked_Access, Before.Index);
         end if;
 
         return;
      end if;
 
      if Before.Container = null
        or else Before.Index > Container.Last
      then
         if Container.Last = Index_Type'Last then
            raise Constraint_Error with
              "vector is already at its maximum length";
         end if;
 
         Index := Container.Last + 1;
 
      else
         Index := Before.Index;
      end if;
 
      Insert_Space (Container, Index, Count => Count);
 
      Position := Cursor'(Container'Unchecked_Access, Index);
   end Insert_Space;
 
   --------------
   -- Is_Empty --
   --------------
 
   function Is_Empty (Container : Vector) return Boolean is
   begin
      return Container.Last < Index_Type'First;
   end Is_Empty;
 
   -------------
   -- Iterate --
   -------------
 
   procedure Iterate
     (Container : Vector;
      Process   : not null access procedure (Position : Cursor))
   is
      V : Vector renames Container'Unrestricted_Access.all;
      B : Natural renames V.Busy;
 
   begin
      B := B + 1;
 
      begin
         for Indx in Index_Type'First .. Container.Last loop
            Process (Cursor'(Container'Unchecked_Access, Indx));
         end loop;
      exception
         when others =>
            B := B - 1;
            raise;
      end;
 
      B := B - 1;
   end Iterate;
 
   ----------
   -- Last --
   ----------
 
   function Last (Container : Vector) return Cursor is
   begin
      if Is_Empty (Container) then
         return No_Element;
      end if;
 
      return (Container'Unchecked_Access, Container.Last);
   end Last;
 
   ------------------
   -- Last_Element --
   ------------------
 
   function Last_Element (Container : Vector) return Element_Type is
   begin
      if Container.Last = No_Index then
         raise Constraint_Error with "Container is empty";
      end if;
 
      return Container.Elements.EA (Container.Last);
   end Last_Element;
 
   ----------------
   -- Last_Index --
   ----------------
 
   function Last_Index (Container : Vector) return Extended_Index is
   begin
      return Container.Last;
   end Last_Index;
 
   ------------
   -- Length --
   ------------
 
   function Length (Container : Vector) return Count_Type is
      L : constant Int := Int (Container.Last);
      F : constant Int := Int (Index_Type'First);
      N : constant Int'Base := L - F + 1;
 
   begin
      return Count_Type (N);
   end Length;
 
   ----------
   -- Move --
   ----------
 
   procedure Move
     (Target : in out Vector;
      Source : in out Vector)
   is
   begin
      if Target'Address = Source'Address then
         return;
      end if;
 
      if Target.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (Target is busy)";
      end if;
 
      if Source.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (Source is busy)";
      end if;
 
      declare
         Target_Elements : constant Elements_Access := Target.Elements;
      begin
         Target.Elements := Source.Elements;
         Source.Elements := Target_Elements;
      end;
 
      Target.Last := Source.Last;
      Source.Last := No_Index;
   end Move;
 
   ----------
   -- Next --
   ----------
 
   function Next (Position : Cursor) return Cursor is
   begin
      if Position.Container = null then
         return No_Element;
      end if;
 
      if Position.Index < Position.Container.Last then
         return (Position.Container, Position.Index + 1);
      end if;
 
      return No_Element;
   end Next;
 
   ----------
   -- Next --
   ----------
 
   procedure Next (Position : in out Cursor) is
   begin
      if Position.Container = null then
         return;
      end if;
 
      if Position.Index < Position.Container.Last then
         Position.Index := Position.Index + 1;
      else
         Position := No_Element;
      end if;
   end Next;
 
   -------------
   -- Prepend --
   -------------
 
   procedure Prepend (Container : in out Vector; New_Item : Vector) is
   begin
      Insert (Container, Index_Type'First, New_Item);
   end Prepend;
 
   procedure Prepend
     (Container : in out Vector;
      New_Item  : Element_Type;
      Count     : Count_Type := 1)
   is
   begin
      Insert (Container,
              Index_Type'First,
              New_Item,
              Count);
   end Prepend;
 
   --------------
   -- Previous --
   --------------
 
   procedure Previous (Position : in out Cursor) is
   begin
      if Position.Container = null then
         return;
      end if;
 
      if Position.Index > Index_Type'First then
         Position.Index := Position.Index - 1;
      else
         Position := No_Element;
      end if;
   end Previous;
 
   function Previous (Position : Cursor) return Cursor is
   begin
      if Position.Container = null then
         return No_Element;
      end if;
 
      if Position.Index > Index_Type'First then
         return (Position.Container, Position.Index - 1);
      end if;
 
      return No_Element;
   end Previous;
 
   -------------------
   -- Query_Element --
   -------------------
 
   procedure Query_Element
     (Container : Vector;
      Index     : Index_Type;
      Process   : not null access procedure (Element : Element_Type))
   is
      V : Vector renames Container'Unrestricted_Access.all;
      B : Natural renames V.Busy;
      L : Natural renames V.Lock;
 
   begin
      if Index > Container.Last then
         raise Constraint_Error with "Index is out of range";
      end if;
 
      B := B + 1;
      L := L + 1;
 
      begin
         Process (V.Elements.EA (Index));
      exception
         when others =>
            L := L - 1;
            B := B - 1;
            raise;
      end;
 
      L := L - 1;
      B := B - 1;
   end Query_Element;
 
   procedure Query_Element
     (Position : Cursor;
      Process  : not null access procedure (Element : Element_Type))
   is
   begin
      if Position.Container = null then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      Query_Element (Position.Container.all, Position.Index, Process);
   end Query_Element;
 
   ----------
   -- Read --
   ----------
 
   procedure Read
     (Stream    : not null access Root_Stream_Type'Class;
      Container : out Vector)
   is
      Length : Count_Type'Base;
      Last   : Index_Type'Base := No_Index;
 
   begin
      Clear (Container);
 
      Count_Type'Base'Read (Stream, Length);
 
      if Length > Capacity (Container) then
         Reserve_Capacity (Container, Capacity => Length);
      end if;
 
      for J in Count_Type range 1 .. Length loop
         Last := Last + 1;
         Element_Type'Read (Stream, Container.Elements.EA (Last));
         Container.Last := Last;
      end loop;
   end Read;
 
   procedure Read
     (Stream   : not null access Root_Stream_Type'Class;
      Position : out Cursor)
   is
   begin
      raise Program_Error with "attempt to stream vector cursor";
   end Read;
 
   ---------------------
   -- Replace_Element --
   ---------------------
 
   procedure Replace_Element
     (Container : in out Vector;
      Index     : Index_Type;
      New_Item  : Element_Type)
   is
   begin
      if Index > Container.Last then
         raise Constraint_Error with "Index is out of range";
      end if;
 
      if Container.Lock > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (vector is locked)";
      end if;
 
      Container.Elements.EA (Index) := New_Item;
   end Replace_Element;
 
   procedure Replace_Element
     (Container : in out Vector;
      Position  : Cursor;
      New_Item  : Element_Type)
   is
   begin
      if Position.Container = null then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      if Position.Container /= Container'Unrestricted_Access then
         raise Program_Error with "Position cursor denotes wrong container";
      end if;
 
      if Position.Index > Container.Last then
         raise Constraint_Error with "Position cursor is out of range";
      end if;
 
      if Container.Lock > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (vector is locked)";
      end if;
 
      Container.Elements.EA (Position.Index) := New_Item;
   end Replace_Element;
 
   ----------------------
   -- Reserve_Capacity --
   ----------------------
 
   procedure Reserve_Capacity
     (Container : in out Vector;
      Capacity  : Count_Type)
   is
      N : constant Count_Type := Length (Container);
 
   begin
      if Capacity = 0 then
         if N = 0 then
            declare
               X : Elements_Access := Container.Elements;
            begin
               Container.Elements := null;
               Free (X);
            end;
 
         elsif N < Container.Elements.EA'Length then
            if Container.Busy > 0 then
               raise Program_Error with
                 "attempt to tamper with elements (vector is busy)";
            end if;
 
            declare
               subtype Src_Index_Subtype is Index_Type'Base range
                 Index_Type'First .. Container.Last;
 
               Src : Elements_Array renames
                       Container.Elements.EA (Src_Index_Subtype);
 
               X : Elements_Access := Container.Elements;
 
            begin
               Container.Elements := new Elements_Type'(Container.Last, Src);
               Free (X);
            end;
         end if;
 
         return;
      end if;
 
      if Container.Elements = null then
         declare
            Last_As_Int : constant Int'Base :=
                            Int (Index_Type'First) + Int (Capacity) - 1;
 
         begin
            if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
               raise Constraint_Error with "new length is out of range";
            end if;
 
            declare
               Last : constant Index_Type := Index_Type (Last_As_Int);
 
            begin
               Container.Elements := new Elements_Type (Last);
            end;
         end;
 
         return;
      end if;
 
      if Capacity <= N then
         if N < Container.Elements.EA'Length then
            if Container.Busy > 0 then
               raise Program_Error with
                 "attempt to tamper with elements (vector is busy)";
            end if;
 
            declare
               subtype Src_Index_Subtype is Index_Type'Base range
                 Index_Type'First .. Container.Last;
 
               Src : Elements_Array renames
                       Container.Elements.EA (Src_Index_Subtype);
 
               X : Elements_Access := Container.Elements;
 
            begin
               Container.Elements := new Elements_Type'(Container.Last, Src);
               Free (X);
            end;
 
         end if;
 
         return;
      end if;
 
      if Capacity = Container.Elements.EA'Length then
         return;
      end if;
 
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      declare
         Last_As_Int : constant Int'Base :=
                         Int (Index_Type'First) + Int (Capacity) - 1;
 
      begin
         if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
            raise Constraint_Error with "new length is out of range";
         end if;
 
         declare
            Last : constant Index_Type := Index_Type (Last_As_Int);
 
            E : Elements_Access := new Elements_Type (Last);
 
         begin
            declare
               subtype Index_Subtype is Index_Type'Base range
                 Index_Type'First .. Container.Last;
 
               Src : Elements_Array renames
                       Container.Elements.EA (Index_Subtype);
 
               Tgt : Elements_Array renames E.EA (Index_Subtype);
 
            begin
               Tgt := Src;
 
            exception
               when others =>
                  Free (E);
                  raise;
            end;
 
            declare
               X : Elements_Access := Container.Elements;
            begin
               Container.Elements := E;
               Free (X);
            end;
         end;
      end;
   end Reserve_Capacity;
 
   ----------------------
   -- Reverse_Elements --
   ----------------------
 
   procedure Reverse_Elements (Container : in out Vector) is
   begin
      if Container.Length <= 1 then
         return;
      end if;
 
      if Container.Lock > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (vector is locked)";
      end if;
 
      declare
         I, J : Index_Type;
         E    : Elements_Type renames Container.Elements.all;
 
      begin
         I := Index_Type'First;
         J := Container.Last;
         while I < J loop
            declare
               EI : constant Element_Type := E.EA (I);
 
            begin
               E.EA (I) := E.EA (J);
               E.EA (J) := EI;
            end;
 
            I := I + 1;
            J := J - 1;
         end loop;
      end;
   end Reverse_Elements;
 
   ------------------
   -- Reverse_Find --
   ------------------
 
   function Reverse_Find
     (Container : Vector;
      Item      : Element_Type;
      Position  : Cursor := No_Element) return Cursor
   is
      Last : Index_Type'Base;
 
   begin
      if Position.Container /= null
        and then Position.Container /= Container'Unchecked_Access
      then
         raise Program_Error with "Position cursor denotes wrong container";
      end if;
 
      Last :=
        (if Position.Container = null or else Position.Index > Container.Last
         then Container.Last
         else Position.Index);
 
      for Indx in reverse Index_Type'First .. Last loop
         if Container.Elements.EA (Indx) = Item then
            return (Container'Unchecked_Access, Indx);
         end if;
      end loop;
 
      return No_Element;
   end Reverse_Find;
 
   ------------------------
   -- Reverse_Find_Index --
   ------------------------
 
   function Reverse_Find_Index
     (Container : Vector;
      Item      : Element_Type;
      Index     : Index_Type := Index_Type'Last) return Extended_Index
   is
      Last : constant Index_Type'Base :=
               Index_Type'Min (Container.Last, Index);
 
   begin
      for Indx in reverse Index_Type'First .. Last loop
         if Container.Elements.EA (Indx) = Item then
            return Indx;
         end if;
      end loop;
 
      return No_Index;
   end Reverse_Find_Index;
 
   ---------------------
   -- Reverse_Iterate --
   ---------------------
 
   procedure Reverse_Iterate
     (Container : Vector;
      Process   : not null access procedure (Position : Cursor))
   is
      V : Vector renames Container'Unrestricted_Access.all;
      B : Natural renames V.Busy;
 
   begin
      B := B + 1;
 
      begin
         for Indx in reverse Index_Type'First .. Container.Last loop
            Process (Cursor'(Container'Unchecked_Access, Indx));
         end loop;
      exception
         when others =>
            B := B - 1;
            raise;
      end;
 
      B := B - 1;
   end Reverse_Iterate;
 
   ----------------
   -- Set_Length --
   ----------------
 
   procedure Set_Length (Container : in out Vector; Length : Count_Type) is
   begin
      if Length = Vectors.Length (Container) then
         return;
      end if;
 
      if Container.Busy > 0 then
         raise Program_Error with
           "attempt to tamper with elements (vector is busy)";
      end if;
 
      if Length > Capacity (Container) then
         Reserve_Capacity (Container, Capacity => Length);
      end if;
 
      declare
         Last_As_Int : constant Int'Base :=
                         Int (Index_Type'First) + Int (Length) - 1;
      begin
         Container.Last := Index_Type'Base (Last_As_Int);
      end;
   end Set_Length;
 
   ----------
   -- Swap --
   ----------
 
   procedure Swap (Container : in out Vector; I, J : Index_Type) is
   begin
      if I > Container.Last then
         raise Constraint_Error with "I index is out of range";
      end if;
 
      if J > Container.Last then
         raise Constraint_Error with "J index is out of range";
      end if;
 
      if I = J then
         return;
      end if;
 
      if Container.Lock > 0 then
         raise Program_Error with
           "attempt to tamper with cursors (vector is locked)";
      end if;
 
      declare
         EI_Copy : constant Element_Type := Container.Elements.EA (I);
      begin
         Container.Elements.EA (I) := Container.Elements.EA (J);
         Container.Elements.EA (J) := EI_Copy;
      end;
   end Swap;
 
   procedure Swap (Container : in out Vector; I, J : Cursor) is
   begin
      if I.Container = null then
         raise Constraint_Error with "I cursor has no element";
      end if;
 
      if J.Container = null then
         raise Constraint_Error with "J cursor has no element";
      end if;
 
      if I.Container /= Container'Unrestricted_Access then
         raise Program_Error with "I cursor denotes wrong container";
      end if;
 
      if J.Container /= Container'Unrestricted_Access then
         raise Program_Error with "J cursor denotes wrong container";
      end if;
 
      Swap (Container, I.Index, J.Index);
   end Swap;
 
   ---------------
   -- To_Cursor --
   ---------------
 
   function To_Cursor
     (Container : Vector;
      Index     : Extended_Index) return Cursor
   is
   begin
      if Index not in Index_Type'First .. Container.Last then
         return No_Element;
      end if;
 
      return Cursor'(Container'Unchecked_Access, Index);
   end To_Cursor;
 
   --------------
   -- To_Index --
   --------------
 
   function To_Index (Position : Cursor) return Extended_Index is
   begin
      if Position.Container = null then
         return No_Index;
      end if;
 
      if Position.Index <= Position.Container.Last then
         return Position.Index;
      end if;
 
      return No_Index;
   end To_Index;
 
   ---------------
   -- To_Vector --
   ---------------
 
   function To_Vector (Length : Count_Type) return Vector is
   begin
      if Length = 0 then
         return Empty_Vector;
      end if;
 
      declare
         First       : constant Int := Int (Index_Type'First);
         Last_As_Int : constant Int'Base := First + Int (Length) - 1;
         Last        : Index_Type;
         Elements    : Elements_Access;
 
      begin
         if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
            raise Constraint_Error with "Length is out of range";
         end if;
 
         Last := Index_Type (Last_As_Int);
         Elements := new Elements_Type (Last);
 
         return Vector'(Controlled with Elements, Last, 0, 0);
      end;
   end To_Vector;
 
   function To_Vector
     (New_Item : Element_Type;
      Length   : Count_Type) return Vector
   is
   begin
      if Length = 0 then
         return Empty_Vector;
      end if;
 
      declare
         First       : constant Int := Int (Index_Type'First);
         Last_As_Int : constant Int'Base := First + Int (Length) - 1;
         Last        : Index_Type;
         Elements    : Elements_Access;
 
      begin
         if Last_As_Int > Index_Type'Pos (Index_Type'Last) then
            raise Constraint_Error with "Length is out of range";
         end if;
 
         Last := Index_Type (Last_As_Int);
         Elements := new Elements_Type'(Last, EA => (others => New_Item));
 
         return Vector'(Controlled with Elements, Last, 0, 0);
      end;
   end To_Vector;
 
   --------------------
   -- Update_Element --
   --------------------
 
   procedure Update_Element
     (Container : in out Vector;
      Index     : Index_Type;
      Process   : not null access procedure (Element : in out Element_Type))
   is
      B : Natural renames Container.Busy;
      L : Natural renames Container.Lock;
 
   begin
      if Index > Container.Last then
         raise Constraint_Error with "Index is out of range";
      end if;
 
      B := B + 1;
      L := L + 1;
 
      begin
         Process (Container.Elements.EA (Index));
      exception
         when others =>
            L := L - 1;
            B := B - 1;
            raise;
      end;
 
      L := L - 1;
      B := B - 1;
   end Update_Element;
 
   procedure Update_Element
     (Container : in out Vector;
      Position  : Cursor;
      Process   : not null access procedure (Element : in out Element_Type))
   is
   begin
      if Position.Container = null then
         raise Constraint_Error with "Position cursor has no element";
      end if;
 
      if Position.Container /= Container'Unrestricted_Access then
         raise Program_Error with "Position cursor denotes wrong container";
      end if;
 
      Update_Element (Container, Position.Index, Process);
   end Update_Element;
 
   -----------
   -- Write --
   -----------
 
   procedure Write
     (Stream    : not null access Root_Stream_Type'Class;
      Container : Vector)
   is
   begin
      Count_Type'Base'Write (Stream, Length (Container));
 
      for J in Index_Type'First .. Container.Last loop
         Element_Type'Write (Stream, Container.Elements.EA (J));
      end loop;
   end Write;
 
   procedure Write
     (Stream   : not null access Root_Stream_Type'Class;
      Position : Cursor)
   is
   begin
      raise Program_Error with "attempt to stream vector cursor";
   end Write;
 
end Ada.Containers.Vectors;