Delphi 2009泛型容器單元(Generics.Collections)[2]: TQueue<T>

TQueue 和 TStack, 一個是隊列列表, 一個是堆棧列表; 一個是先進先出, 一個是先進後出.

TQueue 主要有三個方法、一個屬性:

Enqueue(入列)、Dequeue(出列)、Peek(查看下一個要出列的元素);

Count(元素總數).

本例效果圖:

代碼文件: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 新增的泛型容器單元}
type
　TRec = record
　　Name: string;
　　Age: Word;
　end;
var
　Queue: TQueue<TRec>;　{定義一個泛型 TQueue 類, 這指定了要用於上面定義的 TRec 記錄}
{建立}
procedure TForm1.FormCreate(Sender: TObject);
begin
　Queue := TQueue<TRec>.Create;
　Memo1.Clear;
　Button1.Caption := Button1.Caption + ' 入列';
　Button2.Caption := Button2.Caption + ' 出列';
　Button3.Caption := Button3.Caption + ' 下一個出列的...';
end;
{釋放}
procedure TForm1.FormDestroy(Sender: TObject);
begin
　Queue.Free;
end;
{入列: Enqueue}
procedure TForm1.Button1Click(Sender: TObject);
var
　rec: TRec;
begin
　rec.Name := StringOfChar(Char(65 + Random(26)), 3);
　rec.Age := Random(150);
　Queue.Enqueue(rec);
　Text := Format('當前隊列成員總數: %d', [Queue.Count]);
　{讓 Memo1 配合顯示}
　Memo1.Lines.Add(Format('%s, %d', [rec.Name, rec.Age]));
end;
{出列: Dequeue}
procedure TForm1.Button2Click(Sender: TObject);
var
　rec: TRec;
begin
　if Queue.Count = 0 then Exit;
　rec := Queue.Dequeue;
　ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
　Text := Format('當前隊列成員總數: %d', [Queue.Count]);
　{讓 Memo1 配合顯示}
　Memo1.Lines.Delete(0);
end;
{下一個出列的元素: Peek}
procedure TForm1.Button3Click(Sender: TObject);
var
　rec: TRec;
begin
　if Queue.Count = 0 then Exit;
　rec := Queue.Peek;
　ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
end;
end.

窗體文件:

object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClientHeight = 147
　ClientWidth = 284
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnDestroy = FormDestroy
　PixelsPerInch = 96
　TextHeight = 13
　object Memo1: TMemo
　　Left = 0
　　Top = 0
　　Width = 121
　　Height = 147
　　Align = alLeft
　　Font.Charset = DEFAULT_CHARSET
　　Font.Color = clWindowText
　　Font.Height = -13
　　Font.Name = 'Courier New'
　　Font.Style = []
　　Lines.Strings = (
　　　'Memo1')
　　ParentFont = False
　　ScrollBars = ssBoth
　　TabOrder = 0
　　ExplicitHeight = 201
　end
　object Button1: TButton
　　Left = 127
　　Top = 21
　　Width = 146
　　Height = 25
　　Caption = 'Button1'
　　TabOrder = 1
　　OnClick = Button1Click
　end
　object Button2: TButton
　　Left = 127
　　Top = 61
　　Width = 146
　　Height = 25
　　Caption = 'Button2'
　　TabOrder = 2
　　OnClick = Button2Click
　end
　object Button3: TButton
　　Left = 127
　　Top = 99
　　Width = 146
　　Height = 25
　　Caption = 'Button3'
　　TabOrder = 3
　　OnClick = Button3Click
　end
end