source: branches/textos/Apps/Calculator/UCalculator.pas

unit UCalculator;

{$mode delphi}

interface

uses
  Classes, SysUtils, UApp;

type

  { TAppCalculator }

  TAppCalculator = class(TApp)
  private
    Line: string;
  public
    procedure OnStart; override;
    procedure OnTerminate; override;
    function Evaluate(Text: string): string;
    procedure OnInputText; override;
    constructor Create; override;
  end;

implementation

{ TAppCalculator }

procedure TAppCalculator.OnStart;
begin
  Api.OutputText('Calcualtor 1.0' + LineEnding);
end;

procedure TAppCalculator.OnTerminate;
begin
  Api.OutputText('Bye' + LineEnding);
end;

function TAppCalculator.Evaluate(Text: string): string;
begin
  if Text = '1+1' then Result := '=2'
  else Result := 'Error';
end;

procedure TAppCalculator.OnInputText;
var
  Text: string;
begin
  Text := Api.InputText;
  Api.OutputText(Text);
  if Text[1] = #13 then begin
    if Line = 'exit' then Terminate
    else Api.OutputText(LineEnding + Evaluate(Line) + LineEnding);
    Line := '';
  end else Line := Line + Text;
end;

constructor TAppCalculator.Create;
begin
  inherited;
  Name := 'Calculator';
end;

end.