Delphi双向链表类

unit DvsLinkingClass;
interface
uses
Windows, Messages, SysUtils, Classes, Controls, Forms, Dialogs;
type
PRecLinkNode = ^RecLinkNode;
RecLinkNode = record
NodeMsg: String;
Counter: Integer;
Previous: PRecLinkNode;
Next: PRecLinkNode;
end;
TLinkingClass = class
private
//FNode,LNode:PRecLinkNode;
public
FNode,LNode:PRecLinkNode;
constructor create;
destructor destroy; override;
procedure AddNode(S:String);
procedure DeleteFNode(S:String);
procedure BakupMsg;
end;
implementation
var
LinkingClass: TLinkingClass;
constructor TLinkingClass.create;
begin
inherited;
FNode := nil;
LNode := nil;
end;
procedure TLinkingClass.AddNode(S:String);
var
p:PRecLinkNode;
begin
new(p);
if FNode = nil then
begin
LNode:=FNode;
p.NodeMsg:=S;
p.Next:=FNode;
p.Previous:=FNode;
FNode:=p;
LNode:=p;
end else
begin
LNode.Next:=p;
p.NodeMsg:=S;
p.Next:=nil;
p.Previous:=LNode;
LNode:=p;
end;
end;
procedure TLinkingClass.DeleteFNode(S:String);
var
p:PRecLinkNode;
begin
p := FNode;
begin
FNode := FNode.next;
dispose(p);
end;
end;
destructor TLinkingClass.destroy;
var
p:PRecLinkNode;
begin
//BakupMsg;
while FNode <> nil do
begin
p := FNode;
FNode := FNode.next;
dispose(p);
end;
inherited;
end;
procedure TLinkingClass.BakupMsg;
var
Msg:TStringList;
p:PRecLinkNode;
sSavePath: string;
begin
sSavePath := ExtractFilePath(Application.ExeName)
+ FormatDateTime('YYYYMMDD_HHMMSS', Now) + 'BakMsg' + '.txt';
Msg:=TStringList.Create;
if FNode <> nil then
try
while FNode <> nil do
begin
p := FNode;
Msg.Add(p.NodeMsg);
FNode := FNode.next;
end;
finally
Msg.SaveToFile(sSavePath);
FreeAndNil(Msg);
end;
end;
initialization
LinkingClass := TLinkingClass.create;
finalizati