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476 | -- --
-- package Copyright (c) Dmitry A. Kazakov --
-- Generic_Doubly_Linked_Web Luebeck --
-- Interface Autumn, 2006 --
-- --
-- Last revision : 10:35 22 Oct 2011 --
-- --
-- This library is free software; you can redistribute it and/or --
-- modify it under the terms of the GNU General Public License as --
-- published by the Free Software Foundation; either version 2 of --
-- the License, or (at your option) any later version. This library --
-- is distributed in the hope that it will be useful, but WITHOUT --
-- ANY WARRANTY; without even the implied warranty of --
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU --
-- General Public License for more details. You should have --
-- received a copy of the GNU General Public License along with --
-- this library; if not, write to the Free Software Foundation, --
-- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from --
-- this unit, or you link this unit with other files to produce an --
-- executable, this unit does not by itself cause the resulting --
-- executable to be covered by the GNU General Public License. This --
-- exception does not however invalidate any other reasons why the --
-- executable file might be covered by the GNU Public License. --
--____________________________________________________________________--
--
-- This generic package provides double-linked lists of items. Items
-- can be of any type. The type of the items is the formal parameter
-- List_Item_Type. The items of the list are never copied when
-- inserted, moved or removed from a list. All operations on the lists
-- and their items are referential. An item may participate several
-- lists of different types. The set of types is determined by the
-- formal parameter List_Identification_Type, which is a discrete type.
-- For each value of this type each item becomes a pair of pointers
-- (links). So the number of values of List_Identification_Type
-- determines the number of lists an item can be simultaneously
-- situated in. For a standard doubly-linked list where an item can be
-- in only one list, the parameter List_Identification_Type could be,
-- for example:
--
-- type List_Identification is (The_List);
--
-- The items are allocated in the storage pool specified by the formal
-- parameter Pool. The package provides the access type Node for
-- referencing the items and the access type Web to reference the head
-- items of lists. Note that each list is circular, so any of its items
-- can be considered as a head. A distinct type was chosen only to
-- separate pointers to items and lists, which is important for
-- aliasing prevention. All list operations are defined in terms of
-- Node and Web. Naturally Web and Node are freely convertible to each
-- other.
--
-- A list item is created by using the allocator new. The obtained
-- pointer is passed to Add or Insert as appropriate. The procedure
-- Append is used for creating a new list. The list is specified by a
-- pointer to its head. So it can be create like:
--
-- Head : Web; -- Empty list
-- begin
-- Append (The_List, Head, new Object);
--
-- Now Head points to the newly allocated item in the list. Subsequent
-- items can be created as:
--
-- Append (The_List, Head, new Object);
--
-- The first parameter of all list operations is the type of the list.
-- If, there were several types of lists, we could place the same item
-- into different lists. For example:
--
-- type List_Identification is (Alarm, Log);
-- ...
-- Signal := new Error_Message;
-- Append (Alarm, Notifications_List, Signal);
-- Append (Log, System_Trace_List, Signal);
--
-- Both Append (Prepend) and Insert are intended for placing newly
-- allocated items or items removed from their lists before. To move an
-- item from one list to another of the same type, Append and Insert
-- take an additional parameter of the source list head. The difference
-- between Append and Insert, is that for Append the list head is
-- specified and thus the list can empty. For Insert the list head is
-- not identified and the list cannot be empty.
--
with System; use System;
with System.Storage_Elements; use System.Storage_Elements;
with System.Storage_Pools; use System.Storage_Pools;
generic
type List_Identification_Type is (<>);
type List_Item_Type (<>) is limited private;
Pool : in out Root_Storage_Pool'Class;
package Generic_Doubly_Linked_Web is
--
-- Items_Storage_Pool -- The type of a proxy pool that keeps the items
-- of all lists. The memory for the items is taken
-- from another pool, which is specified as the
-- discriminant.
--
-- Host - The pool to take the memory from
--
type Items_Storage_Pool (Host : access Root_Storage_Pool'Class) is
new Root_Storage_Pool with null record;
--
-- Allocate -- Overrides System.Storage_Pools...
--
procedure Allocate
( Pool : in out Items_Storage_Pool;
Storage_Address : out Address;
Size : Storage_Count;
Alignment : Storage_Count
);
--
-- Deallocate -- Overrides System.Storage_Pools...
--
procedure Deallocate
( Pool : in out Items_Storage_Pool;
Storage_Address : in Address;
Size : Storage_Count;
Alignment : Storage_Count
);
--
-- Storage_Size -- Overrides System.Storage_Pools...
--
function Storage_Size (Pool : Items_Storage_Pool)
return Storage_Count;
--
-- Items_Pool -- The pool of the list items
--
Items_Pool : Items_Storage_Pool (Pool'Access);
--
-- Node -- Pointers to the list items. Each item is a node of a network
-- of lists, because an item can participate in many lists The
-- T'Size representation clause is used to prevent the compiler
-- from making it a fat pointer, which would not fit a word.
--
type Node is access List_Item_Type;
for Node'Storage_Pool use Items_Pool;
for Node'Size use Integer_Address'Size;
--
-- Web -- The type of lists rooted in an item. Both Node and Web are
-- pointers to an item
--
type Web is new Node;
--
-- Append -- Item to a list
--
-- Brand - Of the list
-- Container - The list
-- Element - To be inserted
--
-- This procedure inserts Element at the end of Container. Element is
-- either a newly allocated item or an item outside any lists of the
-- type Brand. Constraint_Error is propagated when Element already is in
-- a list. This includes Container. Container can be empty before a call
-- to the procedure, in which case Element becomes the head of it.
--
-- Exceptions :
--
-- Constraint_Error - Element is in a list or null
--
procedure Append
( Brand : List_Identification_Type;
Container : in out Web;
Element : Node
);
--
-- Append -- Item to a list taking it from another
--
-- Brand - Of the list
-- Container - The list to insert into
-- Element - To move
-- Source - The list to remove from
--
-- This procedure is an equivalent to Remove followed by Append. When
-- Source and Container is the same list Container parameter takes
-- advantage. The operation is void when Container = Element.
--
-- Exceptions :
--
-- Constraint_Error - Element is null
--
procedure Append
( Brand : List_Identification_Type;
Container : in out Web;
Element : Node;
Source : in out Web
);
--
-- Delete -- Item from the list
--
-- Brand - Of the list
-- Container - The list
-- Element - To remove and free
--
-- This procedure removes Element from Container. The item following
-- Element becomes the new list head. The operation is void when Element
-- is null. Container is ignored when null. When Element after its
-- removal does not belong to any list its target object is finalized,
-- freed, and then Element is set to null.
--
procedure Delete
( Brand : List_Identification_Type;
Container : in out Web;
Element : in out Node
);
--
-- Erase -- Item from the list
--
-- Brand - Of the list
-- Container - The list
--
-- This procedure removes all elements from Container. When an element
-- after its removal does not belong to any list its target object is
-- finalized, and freed.
--
procedure Erase
( Brand : List_Identification_Type;
Container : in out Web
);
--
-- Dope_Size -- The size of the List_Item_Type dope
--
-- Returns :
--
-- Size in storage elements
--
-- This function returns the number of storage elements the compiler
-- places in front of an item. The value is estimated and is available
-- only after first call to a list operation.
--
-- Exception :
--
-- Constraint_Error - The size is yet not determined
--
function Dope_Size return Storage_Offset;
--
-- Insert -- Item into a list
--
-- Brand - Of the list
-- Position - An item in the list
-- Element - The item to insert
--
-- Insert is similar to Append, with the difference that an arbitrary
-- list item is used to indicate the insertion position. For this reason
-- Add can deal with empty lists, while Insert requires at least one
-- item in. Element is inserted after the item specified by the
-- parameter Position. Element may not be in any list. Constraint_Error
-- is propagated otherwise or when Element is null. Constraint_Error is
-- also propagated when Position is null or not in a list. To insert
-- Element before Position use:
--
-- Insert (Brand, Previous (Brand, Position), Element);
--
-- Exceptions :
--
-- Constraint_Error - Element is in a list or null, Position is null
-- or not in any list
--
procedure Insert
( Brand : List_Identification_Type;
Position : Node;
Element : Node
);
--
-- Insert -- Item taking it from a list
--
-- Brand - Of the list
-- Position - An item in the list
-- Element - To move to Position
-- Source - The list to remove Element from
--
-- This procedure is an equivalent to Remove followed by Insert. It is
-- void when Position = Element.
--
-- Exceptions :
--
-- Constraint_Error - Element is null, Position is null or not in any
-- list
--
procedure Insert
( Brand : List_Identification_Type;
Position : Node;
Element : Node;
Source : in out Web
);
--
-- Is_Empty -- Check if Container is empty
--
-- Brand - Of the list
-- Container - A list
--
-- Returns :
--
-- True if Container is null
--
function Is_Empty
( Brand : List_Identification_Type;
Container : Web
) return Boolean;
--
-- Is_In -- Check if Element is in a list
--
-- Brand - Of the list
-- Element - An element
--
-- Returns :
--
-- False if Element is null or not in any list of Brand type
--
function Is_In
( Brand : List_Identification_Type;
Element : Node
) return Boolean;
--
-- Is_In -- Check if Element is in any list
--
-- Element - An element
--
-- Returns :
--
-- False if Element is null or not in any list
--
function Is_In (Element : Node) return Boolean;
--
-- Merge -- Two lists
--
-- Brand - Of the list
-- Head - The list to append
-- Tail - The list to prepend
--
-- Either list can be empty. When Head = Tail the operation is void.
--
procedure Merge
( Brand : List_Identification_Type;
Head : in out Web;
Tail : in out Web
);
--
-- Next -- The next item
--
-- Brand - Of the list
-- Container / Element - A list or an it item
--
-- Returns :
--
-- The item following Element
--
-- Exceptions :
--
-- Constraint_Error - Element is not in a list or null
--
function Next
( Brand : List_Identification_Type;
Element : Node
) return Node;
function Next
( Brand : List_Identification_Type;
Container : Web
) return Node;
--
-- Prepend -- Item to a list
--
-- Brand - Of the list
-- Container - The list
-- Element - To be inserted
--
-- This procedure inserts Element in front of Container. Element is
-- either a newly allocated item or an item outside any lists of the
-- type Brand. Constraint_Error is propagated when Element already is in
-- a list. This includes Container. Container can be empty before a call
-- to the procedure.
--
-- Exceptions :
--
-- Constraint_Error - Element is in a list or null
--
procedure Prepend
( Brand : List_Identification_Type;
Container : in out Web;
Element : Node
);
--
-- Prepend -- Item to a list taking it from another
--
-- Brand - Of the list
-- Container - The list to insert into
-- Element - To move
-- Source - The list to remove from
--
-- This procedure is an equivalent to Remove followed by Prepend. When
-- Source and Container is the same list Container parameter takes
-- advantage. It is void when Container = Element.
--
-- Exceptions :
--
-- Constraint_Error - Element is null
--
procedure Prepend
( Brand : List_Identification_Type;
Container : in out Web;
Element : Node;
Source : in out Web
);
--
-- Previous -- The previous item
--
-- Brand - Of the list
-- Container / Element - A list or an it item
--
-- Returns :
--
-- The previous item
--
-- Exceptions :
--
-- Constraint_Error - Element is not in a list or null
--
function Previous
( Brand : List_Identification_Type;
Element : Node
) return Node;
function Previous
( Brand : List_Identification_Type;
Container : Web
) return Node;
--
-- Remove -- Item from the list
--
-- Brand - Of the list
-- Container - The list
-- Element - To removed
--
-- This procedure removes Element from Container. The item following
-- Item becomes the new head. Otherwise, when Element is the last item
-- of the list, Container becomes empty. The operation is void when Item
-- is not in a list or null. Container is ignored when null.
--
procedure Remove
( Brand : List_Identification_Type;
Container : in out Web;
Element : Node
);
--
-- Take -- The first item from
--
-- Container - The list
-- Element - Removed from
--
-- This procedure removes the first element from Container. The result
-- is returned in the parameter Element. When Container is null, Element
-- is also set to null. When Is_In (Element) returns false, then it
-- becomes the caller's responsibility to delete it, or else to return
-- in a list.
--
procedure Take
( Brand : List_Identification_Type;
Container : in out Web;
Element : out Node
);
private
pragma Inline (Append);
pragma Inline (Delete);
pragma Inline (Insert);
pragma Inline (Insert);
pragma Inline (Is_Empty);
pragma Inline (Is_In);
pragma Inline (Next);
pragma Inline (Prepend);
pragma Inline (Previous);
pragma Inline (Remove);
pragma Inline (Take);
end Generic_Doubly_Linked_Web;
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