anchor.diff:  procedure TDStringBuilder.Clear;
   begin
     FPosition := 0;
  +
  +  // modify by ymf
  +  // 2017-01-10 17:36:13
  +  FCapacity := 0;
  +  SetLength(FData, 0);
   end;
   
   function TDStringBuilder.GetLength: Integer;
  
positive.code: begin
    FSize := 0;
    FPosition := 0;
    {$IFDEF MSWINDOWS}
    {$IFDEF DEBUG}
    ZeroMemory(@FData[0], FCapacity);
    {$ENDIF}
    {$ENDIF}
  end;
  
  function TDBufferBuilder.DecodeUTF8: string;
  
negative.code:     FCapacity :Integer;
      FBufferLocked:Boolean;
      FLineBreak: String;
  
      procedure CheckNeedSize(pvSize: LongInt); overload;
      procedure CheckNeedSize(pvOffset, pvSize: LongInt); overload;
      function GetLength: Integer;
  