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{
Copyright (c) 1998-2002 by Daniel Mantione
This unit contains support routines for the state tracker
This program 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 program 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 program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
****************************************************************************
}
unit nstate;
{$i fpcdefs.inc}
interface
uses cclasses,node;
type Tstate_entry=class(Tlinkedlistitem)
what:Tnode;
value:Tnode;
constructor create(w,v:Tnode);
end;
Tstate_storage=class
storage:Tlinkedlist;
constructor create;
procedure store_fact(w,v:Tnode);
function find_fact(what:Tnode):Tnode;
procedure delete_fact(what:Tnode);
end;
var aktstate:Tstate_storage;
implementation
constructor Tstate_entry.create(w,v:Tnode);
begin
inherited create;
what:=w;
value:=v;
end;
constructor Tstate_storage.create;
begin
storage:=Tlinkedlist.create;
end;
procedure Tstate_storage.store_fact(w,v:Tnode);
var se:Tstate_entry;
begin
{ writeln('fact:');
writenode(w);
writeln('=');
writenode(v);}
se:=Tstate_entry(storage.first);
while assigned(se) do
begin
if se.what.isequal(w) then
begin
storage.remove(se);
se.destroy;
break;
end;
se:=Tstate_entry(se.next);
end;
se:=Tstate_entry.create(w,v);
storage.concat(se);
end;
function Tstate_storage.find_fact(what:Tnode):Tnode;
var se:Tstate_entry;
begin
find_fact:=nil;
se:=storage.first as Tstate_entry;
while assigned(se) do
begin
if se.what.isequal(what) then
begin
find_fact:=se.value;
break;
end;
se:=se.next as Tstate_entry;
end;
end;
procedure Tstate_storage.delete_fact(what:Tnode);
var se:Tstate_entry;
begin
se:=storage.first as Tstate_entry;
while assigned(se) do
begin
if se.what.isequal(what) then
begin
storage.remove(se);
se.destroy;
break;
end;
se:=se.next as Tstate_entry;
end;
end;
end.
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