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

--                                                                          --

--                         GNAT LIBRARY COMPONENTS                          --

--                                                                          --

--         A D A . C O N T A I N E R S . M U L T I W A Y _ T R E E S        --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 2004-2012, 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 unit was originally developed by Matthew J Heaney.                  --

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

with Ada.Iterator_Interfaces;

private with Ada.Finalization;

private with Ada.Streams;

generic

   type Element_Type is private;

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

package Ada.Containers.Multiway_Trees is

   pragma Preelaborate;

   pragma Remote_Types;

   type Tree is tagged private

     with Constant_Indexing => Constant_Reference,

          Variable_Indexing => Reference,

          Default_Iterator  => Iterate,

          Iterator_Element  => Element_Type;

   pragma Preelaborable_Initialization (Tree);

   type Cursor is private;

   pragma Preelaborable_Initialization (Cursor);

   Empty_Tree : constant Tree;

   No_Element : constant Cursor;

   function Has_Element (Position : Cursor) return Boolean;

   package Tree_Iterator_Interfaces is new

     Ada.Iterator_Interfaces (Cursor, Has_Element);

   function Equal_Subtree

     (Left_Position  : Cursor;

      Right_Position : Cursor) return Boolean;

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

   function Is_Empty (Container : Tree) return Boolean;

   function Node_Count (Container : Tree) return Count_Type;

   function Subtree_Node_Count (Position : Cursor) return Count_Type;

   function Depth (Position : Cursor) return Count_Type;

   function Is_Root (Position : Cursor) return Boolean;

   function Is_Leaf (Position : Cursor) return Boolean;

   function Root (Container : Tree) return Cursor;

   procedure Clear (Container : in out Tree);

   function Element (Position : Cursor) return Element_Type;

   procedure Replace_Element

     (Container : in out Tree;

      Position  : Cursor;

      New_Item  : Element_Type);

   procedure Query_Element

     (Position : Cursor;

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

   procedure Update_Element

     (Container : in out Tree;

      Position  : Cursor;

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

   type Constant_Reference_Type

     (Element : not null access constant Element_Type) is private

        with Implicit_Dereference => Element;

   type Reference_Type

     (Element : not null access Element_Type) is private

        with Implicit_Dereference => Element;

   function Constant_Reference

     (Container : aliased Tree;

      Position  : Cursor) return Constant_Reference_Type;

   pragma Inline (Constant_Reference);

   function Reference

     (Container : aliased in out Tree;

      Position  : Cursor) return Reference_Type;

   pragma Inline (Reference);

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

   function Copy (Source : Tree) return Tree;

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

   procedure Delete_Leaf

     (Container : in out Tree;

      Position  : in out Cursor);

   procedure Delete_Subtree

     (Container : in out Tree;

      Position  : in out Cursor);

   procedure Swap

     (Container : in out Tree;

      I, J      : Cursor);

   function Find

     (Container : Tree;

      Item      : Element_Type) return Cursor;

   --  This version of the AI:

   --   10-06-02  AI05-0136-1/07

   --  declares Find_In_Subtree this way:

   --

   --  function Find_In_Subtree

   --    (Container : Tree;

   --     Item      : Element_Type;

   --     Position  : Cursor) return Cursor;

   --

   --  It seems that the Container parameter is there by mistake, but we need

   --  an official ruling from the ARG. ???

   function Find_In_Subtree

     (Position : Cursor;

      Item     : Element_Type) return Cursor;

   --  This version of the AI:

   --   10-06-02  AI05-0136-1/07

   --  declares Ancestor_Find this way:

   --

   --  function Ancestor_Find

   --    (Container : Tree;

   --     Item      : Element_Type;

   --     Position  : Cursor) return Cursor;

   --

   --  It seems that the Container parameter is there by mistake, but we need

   --  an official ruling from the ARG. ???

   function Ancestor_Find

     (Position : Cursor;

      Item     : Element_Type) return Cursor;

   function Contains

     (Container : Tree;

      Item      : Element_Type) return Boolean;

   procedure Iterate

     (Container : Tree;

      Process   : not null access procedure (Position : Cursor));

   procedure Iterate_Subtree

     (Position : Cursor;

      Process  : not null access procedure (Position : Cursor));

   function Iterate (Container : Tree)

     return Tree_Iterator_Interfaces.Forward_Iterator'Class;

   function Iterate_Subtree (Position : Cursor)

     return Tree_Iterator_Interfaces.Forward_Iterator'Class;

   function Iterate_Children

     (Container : Tree;

      Parent    : Cursor)

      return Tree_Iterator_Interfaces.Reversible_Iterator'Class;

   function Child_Count (Parent : Cursor) return Count_Type;

   function Child_Depth (Parent, Child : Cursor) return Count_Type;

   procedure Insert_Child

     (Container : in out Tree;

      Parent    : Cursor;

      Before    : Cursor;

      New_Item  : Element_Type;

      Count     : Count_Type := 1);

   procedure Insert_Child

     (Container : in out Tree;

      Parent    : Cursor;

      Before    : Cursor;

      New_Item  : Element_Type;

      Position  : out Cursor;

      Count     : Count_Type := 1);

   procedure Insert_Child

     (Container : in out Tree;

      Parent    : Cursor;

      Before    : Cursor;

      Position  : out Cursor;

      Count     : Count_Type := 1);

   procedure Prepend_Child

     (Container : in out Tree;

      Parent    : Cursor;

      New_Item  : Element_Type;

      Count     : Count_Type := 1);

   procedure Append_Child

     (Container : in out Tree;

      Parent    : Cursor;

      New_Item  : Element_Type;

      Count     : Count_Type := 1);

   procedure Delete_Children

     (Container : in out Tree;

      Parent    : Cursor);

   procedure Copy_Subtree

     (Target   : in out Tree;

      Parent   : Cursor;

      Before   : Cursor;

      Source   : Cursor);

   procedure Splice_Subtree

     (Target   : in out Tree;

      Parent   : Cursor;

      Before   : Cursor;

      Source   : in out Tree;

      Position : in out Cursor);

   procedure Splice_Subtree

     (Container : in out Tree;

      Parent    : Cursor;

      Before    : Cursor;

      Position  : Cursor);

   procedure Splice_Children

     (Target          : in out Tree;

      Target_Parent   : Cursor;

      Before          : Cursor;

      Source          : in out Tree;

      Source_Parent   : Cursor);

   procedure Splice_Children

     (Container       : in out Tree;

      Target_Parent   : Cursor;

      Before          : Cursor;

      Source_Parent   : Cursor);

   function Parent (Position : Cursor) return Cursor;

   function First_Child (Parent : Cursor) return Cursor;

   function First_Child_Element (Parent : Cursor) return Element_Type;

   function Last_Child (Parent : Cursor) return Cursor;

   function Last_Child_Element (Parent : Cursor) return Element_Type;

   function Next_Sibling (Position : Cursor) return Cursor;

   function Previous_Sibling (Position : Cursor) return Cursor;

   procedure Next_Sibling (Position : in out Cursor);

   procedure Previous_Sibling (Position : in out Cursor);

   --  This version of the AI:

   --   10-06-02  AI05-0136-1/07

   --  declares Iterate_Children this way:

   --

   --  procedure Iterate_Children

   --    (Container : Tree;

   --     Parent    : Cursor;

   --     Process   : not null access procedure (Position : Cursor));

   --

   --  It seems that the Container parameter is there by mistake, but we need

   --  an official ruling from the ARG. ???

   procedure Iterate_Children

     (Parent  : Cursor;

      Process : not null access procedure (Position : Cursor));

   procedure Reverse_Iterate_Children

     (Parent  : Cursor;

      Process : not null access procedure (Position : Cursor));

private

   --  A node of this multiway tree comprises an element and a list of children

   --  (that are themselves trees). The root node is distinguished because it

   --  contains only children: it does not have an element itself.

   --

   --  This design feature puts two design goals in tension:

   --   (1) treat the root node the same as any other node

   --   (2) not declare any objects of type Element_Type unnecessarily

   --

   --  To satisfy (1), we could simply declare the Root node of the tree using

   --  the normal Tree_Node_Type, but that would mean that (2) is not

   --  satisfied. To resolve the tension (in favor of (2)), we declare the

   --  component Root as having a different node type, without an Element

   --  component (thus satisfying goal (2)) but otherwise identical to a normal

   --  node, and then use Unchecked_Conversion to convert an access object

   --  designating the Root node component to the access type designating a

   --  normal, non-root node (thus satisfying goal (1)). We make an explicit

   --  check for Root when there is any attempt to manipulate the Element

   --  component of the node (a check required by the RM anyway).

   --

   --  In order to be explicit about node (and pointer) representation, we

   --  specify that the respective node types have convention C, to ensure that

   --  the layout of the components of the node records is the same, thus

   --  guaranteeing that (unchecked) conversions between access types

   --  designating each kind of node type is a meaningful conversion.

   type Tree_Node_Type;

   type Tree_Node_Access is access all Tree_Node_Type;

   pragma Convention (C, Tree_Node_Access);

   type Children_Type is record

      First : Tree_Node_Access;

      Last  : Tree_Node_Access;

   end record;

   --  See the comment above. This declaration must exactly match the

   --  declaration of Root_Node_Type (except for the Element component).

   type Tree_Node_Type is record

      Parent   : Tree_Node_Access;

      Prev     : Tree_Node_Access;

      Next     : Tree_Node_Access;

      Children : Children_Type;

      Element  : aliased Element_Type;

   end record;

   pragma Convention (C, Tree_Node_Type);

   --  See the comment above. This declaration must match the declaration of

   --  Tree_Node_Type (except for the Element component).

   type Root_Node_Type is record

      Parent   : Tree_Node_Access;

      Prev     : Tree_Node_Access;

      Next     : Tree_Node_Access;

      Children : Children_Type;

   end record;

   pragma Convention (C, Root_Node_Type);

   use Ada.Finalization;

   --  The Count component of type Tree represents the number of nodes that

   --  have been (dynamically) allocated. It does not include the root node

   --  itself. As implementors, we decide to cache this value, so that the

   --  selector function Node_Count can execute in O(1) time, in order to be

   --  consistent with the behavior of the Length selector function for other

   --  standard container library units. This does mean, however, that the

   --  two-container forms for Splice_XXX (that move subtrees across tree

   --  containers) will execute in O(n) time, because we must count the number

   --  of nodes in the subtree(s) that get moved. (We resolve the tension

   --  between Node_Count and Splice_XXX in favor of Node_Count, under the

   --  assumption that Node_Count is the more common operation).

   type Tree is new Controlled with record

      Root  : aliased Root_Node_Type;

      Busy  : Natural := 0;

      Lock  : Natural := 0;

      Count : Count_Type := 0;

   end record;

   overriding procedure Adjust (Container : in out Tree);

   overriding procedure Finalize (Container : in out Tree) renames Clear;

   use Ada.Streams;

   procedure Write

     (Stream    : not null access Root_Stream_Type'Class;

      Container : Tree);

   for Tree'Write use Write;

   procedure Read

     (Stream    : not null access Root_Stream_Type'Class;

      Container : out Tree);

   for Tree'Read use Read;

   type Tree_Access is access all Tree;

   for Tree_Access'Storage_Size use 0;

   type Cursor is record

      Container : Tree_Access;

      Node      : Tree_Node_Access;

   end record;

   procedure Write

     (Stream   : not null access Root_Stream_Type'Class;

      Position : Cursor);

   for Cursor'Write use Write;

   procedure Read

     (Stream   : not null access Root_Stream_Type'Class;

      Position : out Cursor);

   for Cursor'Read use Read;

   type Reference_Control_Type is

      new Controlled with record

         Container : Tree_Access;

      end record;

   overriding procedure Adjust (Control : in out Reference_Control_Type);

   pragma Inline (Adjust);

   overriding procedure Finalize (Control : in out Reference_Control_Type);

   pragma Inline (Finalize);

   type Constant_Reference_Type

     (Element : not null access constant Element_Type) is

      record

         Control : Reference_Control_Type;

      end record;

   procedure Read

     (Stream : not null access Root_Stream_Type'Class;

      Item   : out Constant_Reference_Type);

   for Constant_Reference_Type'Read use Read;

   procedure Write

     (Stream : not null access Root_Stream_Type'Class;

      Item   : Constant_Reference_Type);

   for Constant_Reference_Type'Write use Write;

   type Reference_Type

     (Element : not null access Element_Type) is

      record

         Control : Reference_Control_Type;

      end record;

   procedure Read

     (Stream : not null access Root_Stream_Type'Class;

      Item   : out Reference_Type);

   for Reference_Type'Read use Read;

   procedure Write

     (Stream : not null access Root_Stream_Type'Class;

      Item   : Reference_Type);

   for Reference_Type'Write use Write;

   Empty_Tree : constant Tree := (Controlled with others => <>);

   No_Element : constant Cursor := (others => <>);

end Ada.Containers.Multiway_Trees;