Delphi 2009泛型容器单元(Generics.Collections)[3]: TStack<T>

TQueue 和 TStack, 一个是队列列表, 一个是堆栈列表; 一个是先进先出, 一个是先进后出.

TStack 主要有三个方法、一个属性:

Push(压栈)、Pop(出栈)、Peek(查看下一个要出栈的元素);

Count(元素总数).

本例效果图:

代码文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls;
type
　TForm1 = class(TForm)
　　Memo1: TMemo;
　　Button1: TButton;
　　Button2: TButton;
　　Button3: TButton;
　　procedure FormCreate(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　　procedure Button1Click(Sender: TObject);
　　procedure Button2Click(Sender: TObject);
　　procedure Button3Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses Generics.Collections; {Delphi 2009 新增的泛型容器单元}
type
　TRec = record
　　Name: string;
　　Age: Word;
　end;
var
　Stack: TStack<TRec>;　{定义一个泛型 TStack 类, 这指定了要用于上面定义的 TRec 记录}
{建立}
procedure TForm1.FormCreate(Sender: TObject);
begin
　Stack := TStack<TRec>.Create;
　Memo1.Clear;
　Button1.Caption := Button1.Caption + ' 压栈';
　Button2.Caption := Button2.Caption + ' 出栈';
　Button3.Caption := Button3.Caption + ' 下一个出栈的...';
end;
{释放}
procedure TForm1.FormDestroy(Sender: TObject);
begin
　Stack.Free;
end;
{压栈: Push}
procedure TForm1.Button1Click(Sender: TObject);
var
　rec: TRec;
begin
　rec.Name := StringOfChar(Char(65 + Random(26)), 3);
　rec.Age := Random(150);
　Stack.Push(rec);
　Text := Format('当前队列成员总数: %d', [Stack.Count]);
　{让 Memo1 配合显示}
　Memo1.Lines.Add(Format('%s, %d', [rec.Name, rec.Age]));
end;
{出栈: Pop}
procedure TForm1.Button2Click(Sender: TObject);
var
　rec: TRec;
begin
　if Stack.Count = 0 then Exit;
　rec := Stack.Pop;
　ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
　Text := Format('当前队列成员总数: %d', [Stack.Count]);
　{让 Memo1 配合显示}
　Memo1.Lines.Delete(Memo1.Lines.Count - 1);
end;
{下一个出列的的元素: Peek}
procedure TForm1.Button3Click(Sender: TObject);
var
　rec: TRec;
begin
　if Stack.Count = 0 then Exit;
　rec := Stack.Peek;
　ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
end;
end.