File : asgc-graph-links-expandable.adb
-- The Ada Structured Library - A set of container classes and general
-- tools for use with Ada95.
-- Copyright (C) 1998-1999 Corey Minyard (minyard@acm.org)
--
-- 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.
--
with Ada.Unchecked_Deallocation;
with Text_IO;
package body Asgc.Graph.Links.Expandable is
---------------------------------------------------------------------
-- IMPORTANT - Expandable graph links store their positions backward
-- in the array, the last element in the array is the first link in
-- the set of links. When a graph node is destroyed, it will delete
-- links one at a time from the first link. Keeping the "first" link
-- at the end of the array improves the efficiency of this operation
-- substantually. However, every operation MUST take this into
-- account and reverse the order of the position and the array index.
procedure Free_Edge_Array is new Ada.Unchecked_Deallocation
(Edge_Array, Edge_Array_Ptr);
---------------------------------------------------------------------
-- Check that an iterator is valid. An iterator is not valid if
-- it has not been initialized of if the Link container has been
-- modified since the last time the iterator's position was set.
procedure Check_Iterator (Iter : in Graph_Link_It'Class) is
begin
if (Iter.Robj = null) then
raise Invalid_Iterator;
end if;
if (Iter.Update /= Iter.Robj.Update) then
raise Invalid_Iterator;
end if;
end Check_Iterator;
---------------------------------------------------------------------
-- Check an iterator, but don't require it to have a valid position.
-- It still must be initialized properly.
procedure Check_Iterator_No_Pos
(Iter : in Graph_Link_It'Class) is
begin
if (Iter.Robj = null) then
raise Invalid_Iterator;
end if;
end Check_Iterator_No_Pos;
---------------------------------------------------------------------
-- The rest of the methods below are are external definitions whose
-- functions are defined in the spec file for this package.
---------------------------------------------------------------------
procedure Free_Graph_Link (Node : in out Graph_Link) is
begin
if (Node.Edges /= null) then
Free_Edge_Array(Node.Edges);
end if;
end Free_Graph_Link;
------------------------------------------------------------------------
procedure Copied_Graph_Link (Node : in out Graph_Link) is
begin
if (Node.Edges /= null) then
Node.Edges := new Edge_Array'(Node.Edges.all);
end if;
end Copied_Graph_Link;
---------------------------------------------------------------------
procedure Set_Node (Iter : in out Graph_Link_It;
Node : in Links.Graph_Link_Class) is
begin
Iter.Robj := Graph_Link_Class(Node);
Iter.Update := Iter.Robj.Update - 1;
end Set_Node;
---------------------------------------------------------------------
procedure Add (Node : in out Graph_Link;
Val : in Link_Type;
Contents : in Link_Contained_Type) is
begin
if (Node.Edges = null) then
Node.Edges := new Edge_Array(1 .. Initial_Size);
elsif (Node.Size = Node.Edges.all'Last) then
declare
New_Edges : Edge_Array_Ptr
:= new Edge_Array(1 .. Node.Edges.all'Last + Increment);
begin
New_Edges.all(1 .. Node.Edges.all'Last) := Node.Edges.all;
Free_Edge_Array(Node.Edges);
Node.Edges := New_Edges;
end;
end if;
Node.Size := Node.Size + 1;
Node.Edges(Node.Size).Val := Val;
Node.Edges(Node.Size).Contents := Contents;
Node.Update := Node.Update + 1;
end Add;
---------------------------------------------------------------------
procedure Delete_First (Node : in out Graph_Link) is
begin
if (Node.Size = 0) then
raise Constraint_Error;
end if;
Node.Size := Node.Size - 1;
Node.Update := Node.Update + 1;
end Delete_First;
---------------------------------------------------------------------
procedure Delete_Val (Node : in out Graph_Link;
Val : in Link_Type;
Instance : in Positive := 1) is
Count : Positive := 1;
begin
for I in reverse 1 .. Node.Size loop
if (Node.Edges(I).Val = Val) then
if (Count = Instance) then
for J in I .. (Node.Size - 1) loop
Node.Edges(J) := Node.Edges(J+1);
end loop;
Node.Size := Node.Size - 1;
return;
else
Count := Count + 1;
end if;
end if;
end loop;
raise Item_Not_Found;
end Delete_Val;
---------------------------------------------------------------------
function Get_Pos (Node : in Graph_Link;
Pos : in Positive)
return Link_Type is
begin
if (Pos > Node.Size) then
raise Constraint_Error;
end if;
return Node.Edges((Node.Size + 1) - Pos).Val;
end Get_Pos;
---------------------------------------------------------------------
function Val_Exists (Node : in Graph_Link;
Val : in Link_Type;
Instance : in Positive := 1)
return Boolean is
Count : Positive := 1;
begin
for I in reverse 1 .. Node.Size loop
if (Node.Edges(I).Val = Val) then
if (Count = Instance) then
return True;
else
Count := Count + 1;
end if;
end if;
end loop;
return False;
end Val_Exists;
---------------------------------------------------------------------
function Get_Contents (Iter : in Graph_Link_It)
return Link_Contained_Type is
begin
Check_Iterator(Iter);
return Iter.Robj.Edges(Iter.Pos).Contents;
end Get_Contents;
---------------------------------------------------------------------
function Get_Contents (Node : in Graph_Link;
Val : in Link_Type;
Instance : in Positive := 1)
return Link_Contained_Type is
Count : Positive := 1;
begin
for I in reverse 1 .. Node.Size loop
if (Node.Edges(I).Val = Val) then
if (Count = Instance) then
return Node.Edges(I).Contents;
else
Count := Count + 1;
end if;
end if;
end loop;
raise Item_Not_Found;
end Get_Contents;
---------------------------------------------------------------------
function Get_First_Contents (Node : in Graph_Link)
return Link_Contained_Type is
begin
return Node.Edges(Node.Size).Contents;
end Get_First_Contents;
---------------------------------------------------------------------
procedure Set_Contents (Iter : in out Graph_Link_It;
Contents : in Link_Contained_Type) is
begin
Check_Iterator(Iter);
Iter.Robj.Edges(Iter.Pos).Contents := Contents;
end Set_Contents;
---------------------------------------------------------------------
procedure Delete (Iter : in out Graph_Link_It;
Is_End : out End_Marker) is
begin
Check_Iterator(Iter);
for I in Iter.Pos .. (Iter.Robj.Size - 1) loop
Iter.Robj.Edges.all(I) := Iter.Robj.Edges.all(I+1);
end loop;
Iter.Robj.Size := Iter.Robj.Size - 1;
Iter.Robj.Update := Iter.Robj.Update + 1;
if (Iter.Pos = 1) then
Is_End := Past_End;
else
Is_End := Not_Past_End;
Iter.Pos := Iter.Pos - 1;
Iter.Update := Iter.Robj.Update;
end if;
end Delete;
---------------------------------------------------------------------
procedure First (Iter : in out Graph_Link_It;
Is_End : out End_Marker) is
begin
Check_Iterator_No_Pos(Iter);
if (Iter.Robj.Size = 0) then
Is_End := Past_End;
else
Is_End := Not_Past_End;
Iter.Pos := Iter.Robj.Size;
Iter.Update := Iter.Robj.Update;
end if;
end First;
---------------------------------------------------------------------
procedure Next (Iter : in out Graph_Link_It;
Is_End : out End_Marker) is
begin
Check_Iterator(Iter);
if (Iter.Pos = 1) then
Is_End := Past_End;
else
Is_End := Not_Past_End;
Iter.Pos := Iter.Pos - 1;
end if;
end Next;
---------------------------------------------------------------------
procedure Find (Iter : in out Graph_Link_It;
Val : in Link_Type;
Found : out Boolean;
Instance : in Positive := 1) is
Count : Positive := 1;
begin
Check_Iterator_No_Pos(Iter);
for I in reverse 1 .. Iter.Robj.Size loop
if (Iter.Robj.Edges(I).Val = Val) then
if (Count /= Instance) then
Count := Count + 1;
else
Iter.Pos := I;
Iter.Update := Iter.Robj.Update;
Found := True;
return;
end if;
end if;
end loop;
Found := False;
end Find;
---------------------------------------------------------------------
procedure Find_Again (Iter : in out Graph_Link_It;
Found : out Boolean) is
Orig : Positive;
begin
Check_Iterator(Iter);
if (Iter.Pos = 1) then
Found := False;
else
Orig := Iter.Pos;
for I in reverse 1 .. (Iter.Pos - 1) loop
if (Iter.Robj.Edges(I).Val = Iter.Robj.Edges(Orig).Val) then
Iter.Pos := I;
Found := True;
return;
end if;
end loop;
Found := False;
end if;
end Find_Again;
---------------------------------------------------------------------
function Get_Instance_Number (Iter : in Graph_Link_It)
return Positive is
Retval : Positive := 1;
begin
for I in reverse (Iter.Pos + 1) .. Iter.Robj.Size loop
if (Iter.Robj.Edges(I).Val = Iter.Robj.Edges(Iter.Pos).Val) then
Retval := Retval + 1;
end if;
end loop;
return Retval;
end Get_Instance_Number;
---------------------------------------------------------------------
function Get_Instance_Number (Node : in Graph_Link;
Pos : in Positive)
return Positive is
Retval : Positive := 1;
Real_Pos : Positive;
begin
if (Pos > Node.Size) then
raise Constraint_Error;
end if;
Real_Pos := (Node.Size + 1) - Pos;
for I in reverse (Real_Pos + 1) .. Node.Size loop
if (Node.Edges(I).Val = Node.Edges(Real_Pos).Val) then
Retval := Retval + 1;
end if;
end loop;
return Retval;
end Get_Instance_Number;
---------------------------------------------------------------------
function Get (Iter : in Graph_Link_It)
return Link_Type is
begin
Check_Iterator(Iter);
return Iter.Robj.Edges.all(Iter.Pos).Val;
end Get;
---------------------------------------------------------------------
function Link_Count (Node : in Graph_Link) return Natural is
begin
return Node.Size;
end Link_Count;
end Asgc.Graph.Links.Expandable;