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unit LazClasses;
{$mode objfpc}{$H+}
interface
uses
sysutils, Classes, LazMethodList;
type
{ TFreeNotifyingObject }
TFreeNotifyingObject = class
private
FFreeNotificationList: TMethodList;
public
constructor Create;
destructor Destroy; override;
procedure AddFreeeNotification(ANotification: TNotifyEvent);
procedure RemoveFreeeNotification(ANotification: TNotifyEvent);
end;
{ TRefCountedObject }
TRefCountedObject = class(TFreeNotifyingObject)
private
FRefCount: Integer;
protected
procedure DoFree; virtual;
property RefCount: Integer read FRefCount;
public
constructor Create;
destructor Destroy; override;
procedure AddReference;
procedure ReleaseReference;
end;
{ TRefCntObjList }
TRefCntObjList = class(TList)
protected
procedure Notify(Ptr: Pointer; Action: TListNotification); override;
end;
procedure ReleaseRefAndNil(var ARefCountedObject);
implementation
{ TFreeNotifyingObject }
constructor TFreeNotifyingObject.Create;
begin
FFreeNotificationList := TMethodList.Create;
inherited Create;
end;
destructor TFreeNotifyingObject.Destroy;
begin
FFreeNotificationList.CallNotifyEvents(Self);
inherited Destroy;
FreeAndNil(FFreeNotificationList);
end;
procedure TFreeNotifyingObject.AddFreeeNotification(ANotification: TNotifyEvent);
begin
FFreeNotificationList.Add(TMethod(ANotification));
end;
procedure TFreeNotifyingObject.RemoveFreeeNotification(ANotification: TNotifyEvent);
begin
FFreeNotificationList.Remove(TMethod(ANotification));
end;
{ TRefCountedObject }
procedure TRefCountedObject.AddReference;
begin
Inc(FRefcount);
end;
procedure TRefCountedObject.DoFree;
begin
Self.Free;
end;
constructor TRefCountedObject.Create;
begin
FRefCount := 0;
inherited;
end;
destructor TRefCountedObject.Destroy;
begin
Assert(FRefcount = 0, 'Destroying referenced object');
inherited;
end;
procedure TRefCountedObject.ReleaseReference;
begin
if Self = nil then exit;
Assert(FRefCount > 0, 'TRefCountedObject.ReleaseReference RefCount > 0');
Dec(FRefCount);
if FRefCount = 0 then DoFree;
end;
{ TRefCntObjList }
procedure TRefCntObjList.Notify(Ptr: Pointer; Action: TListNotification);
begin
case Action of
lnAdded: TRefCountedObject(Ptr).AddReference;
lnExtracted,
lnDeleted: TRefCountedObject(Ptr).ReleaseReference;
end;
end;
procedure ReleaseRefAndNil(var ARefCountedObject);
begin
Assert( (Pointer(ARefCountedObject) = nil) or
(TObject(ARefCountedObject) is TRefCountedObject),
'ReleaseRefAndNil requires TRefCountedObject');
if Pointer(ARefCountedObject) = nil then
exit;
if (TObject(ARefCountedObject) is TRefCountedObject) then
TRefCountedObject(ARefCountedObject).ReleaseReference;
Pointer(ARefCountedObject) := nil;
end;
end.
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