{
  Inno Setup Preprocessor
  Copyright (C) 2001-2002 Alex Yackimoff
  
  Inno Setup
  Copyright (C) 1997-2020 Jordan Russell
  Portions by Martijn Laan
  For conditions of distribution and use, see LICENSE.TXT.
}

unit ISPP.Stack;

interface

uses Classes;

type

{ Borrowed from Delphi 5 Contnrs unit }

{ TOrdered class }

  TOrderedList = class(TObject)
  private
    FList: TList;
  protected
    procedure PushItem(AItem: Pointer); virtual; abstract;
    function PopItem: Pointer; virtual;
    function PeekItem: Pointer; virtual;
    property List: TList read FList;
  public
    constructor Create;
    destructor Destroy; override;

    function Count: Integer;
    function AtLeast(ACount: Integer): Boolean;
    procedure Push(AItem: Pointer);
    function Pop: Pointer;
    function Peek: Pointer;
  end;

{ TStack class }

  TStack = class(TOrderedList)
  protected
    procedure PushItem(AItem: Pointer); override;
  end;


implementation

uses
  ISPP.Consts;

{ TOrderedList }

function TOrderedList.AtLeast(ACount: integer): boolean;
begin
  Result := List.Count >= ACount;
end;

function TOrderedList.Peek: Pointer;
begin
  Result := PeekItem;
end;

function TOrderedList.Pop: Pointer;
begin
  Result := PopItem;
end;

procedure TOrderedList.Push(AItem: Pointer);
begin
  PushItem(AItem);
end;

function TOrderedList.Count: Integer;
begin
  Result := List.Count;
end;

constructor TOrderedList.Create;
begin
  inherited Create;
  FList := TList.Create;
end;

destructor TOrderedList.Destroy;
begin
  List.Free;
  inherited Destroy;
end;

function TOrderedList.PeekItem: Pointer;
begin
  Result := List[List.Count-1];
end;

function TOrderedList.PopItem: Pointer;
begin
  Result := PeekItem;
  List.Delete(List.Count-1);
end;

{ TStack }

procedure TStack.PushItem(AItem: Pointer);
begin
  List.Add(AItem);
end;


end.