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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT LIBRARY COMPONENTS                          --

--                                                                          --

--                 ADA.CONTAINERS.FORMAL_DOUBLY_LINKED_LISTS                --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 2004-2011, Free Software Foundation, Inc.         --

--                                                                          --

-- This specification is derived from the Ada Reference Manual for use with --

-- GNAT. The copyright notice above, and the license provisions that follow --

-- apply solely to the  contents of the part following the private keyword. --

--                                                                          --

-- 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 spec is derived from Ada.Containers.Bounded_Doubly_Linked_Lists in the

--  Ada 2012 RM. The modifications are to facilitate formal proofs by making it

--  easier to express properties.

--  The modifications are:

--    A parameter for the container is added to every function reading the

--    contents of a container: Next, Previous, Query_Element, Has_Element,

--    Iterate, Reverse_Iterate, Element. This change is motivated by the need

--    to have cursors which are valid on different containers (typically a

--    container C and its previous version C'Old) for expressing properties,

--    which is not possible if cursors encapsulate an access to the underlying

--    container.

--    There are three new functions:

--      function Strict_Equal (Left, Right : List) return Boolean;

--      function Left  (Container : List; Position : Cursor) return List;

--      function Right (Container : List; Position : Cursor) return List;

--    See detailed specifications for these subprograms

private with Ada.Streams;

with Ada.Containers;

with Ada.Iterator_Interfaces;

generic

   type Element_Type is private;

   with function "=" (Left, Right : Element_Type)

                      return Boolean is <>;

package Ada.Containers.Formal_Doubly_Linked_Lists is

   pragma Pure;

   type List (Capacity : Count_Type) is tagged private with

      Constant_Indexing => Constant_Reference,

      Default_Iterator  => Iterate,

      Iterator_Element  => Element_Type;

   --  pragma Preelaborable_Initialization (List);

   type Cursor is private;

   pragma Preelaborable_Initialization (Cursor);

   Empty_List : constant List;

   No_Element : constant Cursor;

   function Not_No_Element (Position : Cursor) return Boolean;

   package List_Iterator_Interfaces is new

     Ada.Iterator_Interfaces (Cursor => Cursor, Has_Element => Not_No_Element);

   function Iterate (Container : List; Start : Cursor)

      return List_Iterator_Interfaces.Reversible_Iterator'Class;

   function Iterate (Container : List)

      return List_Iterator_Interfaces.Reversible_Iterator'Class;

   function "=" (Left, Right : List) return Boolean;

   function Length (Container : List) return Count_Type;

   function Is_Empty (Container : List) return Boolean;

   procedure Clear (Container : in out List);

   procedure Assign (Target : in out List; Source : List);

   function Copy (Source : List; Capacity : Count_Type := 0) return List;

   function Element (Container : List; Position : Cursor) return Element_Type;

   procedure Replace_Element

     (Container : in out List;

      Position  : Cursor;

      New_Item  : Element_Type);

   procedure Query_Element

     (Container : List; Position : Cursor;

      Process   : not null access procedure (Element : Element_Type));

   procedure Update_Element

     (Container : in out List;

      Position  : Cursor;

      Process   : not null access procedure (Element : in out Element_Type));

   procedure Move (Target : in out List; Source : in out List);

   procedure Insert

     (Container : in out List;

      Before    : Cursor;

      New_Item  : Element_Type;

      Count     : Count_Type := 1);

   procedure Insert

     (Container : in out List;

      Before    : Cursor;

      New_Item  : Element_Type;

      Position  : out Cursor;

      Count     : Count_Type := 1);

   procedure Insert

     (Container : in out List;

      Before    : Cursor;

      Position  : out Cursor;

      Count     : Count_Type := 1);

   procedure Prepend

     (Container : in out List;

      New_Item  : Element_Type;

      Count     : Count_Type := 1);

   procedure Append

     (Container : in out List;

      New_Item  : Element_Type;

      Count     : Count_Type := 1);

   procedure Delete

     (Container : in out List;

      Position  : in out Cursor;

      Count     : Count_Type := 1);

   procedure Delete_First

     (Container : in out List;

      Count     : Count_Type := 1);

   procedure Delete_Last

     (Container : in out List;

      Count     : Count_Type := 1);

   procedure Reverse_Elements (Container : in out List);

   procedure Swap

     (Container : in out List;

      I, J      : Cursor);

   procedure Swap_Links

     (Container : in out List;

      I, J      : Cursor);

   procedure Splice

     (Target : in out List;

      Before : Cursor;

      Source : in out List);

   procedure Splice

     (Target   : in out List;

      Before   : Cursor;

      Source   : in out List;

      Position : in out Cursor);

   procedure Splice

     (Container : in out List;

      Before    : Cursor;

      Position  : Cursor);

   function First (Container : List) return Cursor;

   function First_Element (Container : List) return Element_Type;

   function Last (Container : List) return Cursor;

   function Last_Element (Container : List) return Element_Type;

   function Next (Container : List; Position : Cursor) return Cursor;

   procedure Next (Container : List; Position : in out Cursor);

   function Previous (Container : List; Position : Cursor) return Cursor;

   procedure Previous (Container : List; Position : in out Cursor);

   function Find

     (Container : List;

      Item      : Element_Type;

      Position  : Cursor := No_Element) return Cursor;

   function Reverse_Find

     (Container : List;

      Item      : Element_Type;

      Position  : Cursor := No_Element) return Cursor;

   function Contains

     (Container : List;

      Item      : Element_Type) return Boolean;

   function Has_Element (Container : List; Position : Cursor) return Boolean;

   procedure Iterate

     (Container : List;

      Process   :

      not null access procedure (Container : List; Position : Cursor));

   procedure Reverse_Iterate

     (Container : List;

      Process   :

      not null access procedure (Container : List; Position : Cursor));

   generic

      with function "<" (Left, Right : Element_Type) return Boolean is <>;

   package Generic_Sorting is

      function Is_Sorted (Container : List) return Boolean;

      procedure Sort (Container : in out List);

      procedure Merge (Target, Source : in out List);

   end Generic_Sorting;

   type Constant_Reference_Type

      (Element : not null access constant Element_Type) is private

   with

      Implicit_Dereference => Element;

   function Constant_Reference

     (Container : List;      --  SHOULD BE ALIASED ???

      Position  : Cursor)   return Constant_Reference_Type;

   function Strict_Equal (Left, Right : List) return Boolean;

   --  Strict_Equal returns True if the containers are physically equal, i.e.

   --  they are structurally equal (function "=" returns True) and that they

   --  have the same set of cursors.

   function Left  (Container : List; Position : Cursor) return List;

   function Right (Container : List; Position : Cursor) return List;

   --  Left returns a container containing all elements preceding Position

   --  (excluded) in Container. Right returns a container containing all

   --  elements following Position (included) in Container. These two new

   --  functions can be used to express invariant properties in loops which

   --  iterate over containers. Left returns the part of the container already

   --  scanned and Right the part not scanned yet.

private

   type Node_Type is record

      Prev    : Count_Type'Base := -1;

      Next    : Count_Type;

      Element : aliased Element_Type;

   end record;

   function "=" (L, R : Node_Type) return Boolean is abstract;

   type Node_Array is array (Count_Type range <>) of Node_Type;

   function "=" (L, R : Node_Array) return Boolean is abstract;

   type List (Capacity : Count_Type) is tagged record

      Nodes  : Node_Array (1 .. Capacity) := (others => <>);

      Free   : Count_Type'Base := -1;

      Busy   : Natural := 0;

      Lock   : Natural := 0;

      Length : Count_Type := 0;

      First  : Count_Type := 0;

      Last   : Count_Type := 0;

   end record;

   use Ada.Streams;

   procedure Read

     (Stream : not null access Root_Stream_Type'Class;

      Item   : out List);

   for List'Read use Read;

   procedure Write

     (Stream : not null access Root_Stream_Type'Class;

      Item   : List);

   for List'Write use Write;

   type List_Access is access all List;

   for List_Access'Storage_Size use 0;

   type Cursor is record

      Node : Count_Type := 0;

   end record;

   procedure Read

     (Stream : not null access Root_Stream_Type'Class;

      Item   : out Cursor);

   for Cursor'Read use Read;

   procedure Write

     (Stream : not null access Root_Stream_Type'Class;

      Item   : Cursor);

   for Cursor'Write use Write;

   Empty_List : constant List := (0, others => <>);

   No_Element : constant Cursor := (Node => 0);

   type Constant_Reference_Type

      (Element : not null access constant Element_Type) is null record;

end Ada.Containers.Formal_Doubly_Linked_Lists;