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{
Free Pascal port of the OpenPTC C++ library.
Copyright (C) 2001-2003, 2010, 2011 Nikolay Nikolov (nickysn@users.sourceforge.net)
Original C++ version by Glenn Fiedler (ptc@gaffer.org)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version
with the following modification:
As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent modules,and
to copy and distribute the resulting executable under terms of your choice,
provided that you also meet, for each linked independent module, the terms
and conditions of the license of that module. An independent module is a
module which is not derived from or based on this library. If you modify
this library, you may extend this exception to your version of the library,
but you are not obligated to do so. If you do not wish to do so, delete this
exception statement from your 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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
}
unit ptceventqueue;
{$MODE objfpc}{$H+}
interface
uses
SysUtils, ptc;
type
PEventLinkedList = ^TEventLinkedList;
TEventLinkedList = record
Event: IPTCEvent;
Next: PEventLinkedList;
end;
TEventQueue = class
private
FHead, FTail: PEventLinkedList;
public
constructor Create;
destructor Destroy; override;
procedure AddEvent(const event: IPTCEvent);
function PeekEvent(const EventMask: TPTCEventMask): IPTCEvent;
function NextEvent(const EventMask: TPTCEventMask): IPTCEvent;
end;
implementation
constructor TEventQueue.Create;
begin
FHead := nil;
FTail := nil;
end;
destructor TEventQueue.Destroy;
var
p, pnext: PEventLinkedList;
begin
p := FHead;
while p <> nil do
begin
p^.Event := nil;
pnext := p^.Next;
Dispose(p);
p := pnext;
end;
inherited Destroy;
end;
procedure TEventQueue.AddEvent(const event: IPTCEvent);
var
tmp: PEventLinkedList;
begin
New(tmp);
FillChar(tmp^, SizeOf(tmp^), 0);
tmp^.Next := nil;
tmp^.Event := event;
if FTail <> nil then
begin
FTail^.Next := tmp;
FTail := tmp;
end
else
begin { FTail = nil }
FHead := tmp;
FTail := tmp;
end;
end;
function TEventQueue.PeekEvent(const EventMask: TPTCEventMask): IPTCEvent;
var
p: PEventLinkedList;
begin
p := FHead;
while p <> nil do
begin
if p^.Event.EventType In EventMask then
begin
Result := p^.Event;
exit;
end;
p := p^.Next;
end;
Result := nil;
end;
function TEventQueue.NextEvent(const EventMask: TPTCEventMask): IPTCEvent;
var
prev, p: PEventLinkedList;
begin
prev := nil;
p := FHead;
while p <> nil do
begin
if p^.Event.EventType In EventMask then
begin
Result := p^.Event;
p^.Event := nil;
{ delete the element from the linked list }
if prev <> nil then
prev^.Next := p^.Next
else
FHead := p^.Next;
if p^.Next = nil then
FTail := prev;
Dispose(p);
exit;
end;
prev := p;
p := p^.Next;
end;
Result := nil;
end;
end.
|
