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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) 2004-2022, 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;
with Ada.Containers.Helpers;
private with Ada.Finalization;
private with Ada.Streams;
private with Ada.Strings.Text_Buffers;
generic
type Element_Type is private;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Multiway_Trees with
SPARK_Mode => Off
is
pragma Annotate (CodePeer, Skip_Analysis);
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 with one another:
-- (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.
use Ada.Containers.Helpers;
package Implementation is new Generic_Implementation;
use Implementation;
type Tree_Node_Type;
type Tree_Node_Access is access all Tree_Node_Type;
pragma Convention (C, Tree_Node_Access);
pragma No_Strict_Aliasing (Tree_Node_Access);
-- The above-mentioned Unchecked_Conversion is a violation of the normal
-- aliasing rules.
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);
for Root_Node_Type'Alignment use Standard'Maximum_Alignment;
-- The alignment has to be large enough to allow Root_Node to Tree_Node
-- access value conversions, and Tree_Node_Type's alignment may be bumped
-- up by the Element component.
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;
TC : aliased Tamper_Counts;
Count : Count_Type := 0;
end record with Put_Image => Put_Image;
procedure Put_Image
(S : in out Ada.Strings.Text_Buffers.Root_Buffer_Type'Class; V : Tree);
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;
subtype Reference_Control_Type is Implementation.Reference_Control_Type;
-- It is necessary to rename this here, so that the compiler can find it
type Constant_Reference_Type
(Element : not null access constant Element_Type) is
record
Control : Reference_Control_Type :=
raise Program_Error with "uninitialized reference";
-- The RM says, "The default initialization of an object of
-- type Constant_Reference_Type or Reference_Type propagates
-- Program_Error."
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 :=
raise Program_Error with "uninitialized reference";
-- The RM says, "The default initialization of an object of
-- type Constant_Reference_Type or Reference_Type propagates
-- Program_Error."
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;
-- Three operations are used to optimize in the expansion of "for ... of"
-- loops: the Next(Cursor) procedure in the visible part, and the following
-- Pseudo_Reference and Get_Element_Access functions. See Exp_Ch5 for
-- details.
function Pseudo_Reference
(Container : aliased Tree'Class) return Reference_Control_Type;
pragma Inline (Pseudo_Reference);
-- Creates an object of type Reference_Control_Type pointing to the
-- container, and increments the Lock. Finalization of this object will
-- decrement the Lock.
type Element_Access is access all Element_Type with
Storage_Size => 0;
function Get_Element_Access
(Position : Cursor) return not null Element_Access;
-- Returns a pointer to the element designated by Position.
Empty_Tree : constant Tree := (Controlled with others => <>);
No_Element : constant Cursor := (others => <>);
end Ada.Containers.Multiway_Trees;