function TryStrToDate(const S: string; out Value: TDateTime;
  const AFormatSettings: TFormatSettings): Boolean;
var
  Pos: Integer;
begin
  Pos := Low(string);
  Result := ScanDate(S, Pos, Value, AFormatSettings) and (Pos > High(S));
end;

function ScanDate(const S: string; var Pos: Integer; var Date: TDateTime;
  const AFormatSettings: TFormatSettings): Boolean; overload;
var
  DateOrder: TDateOrder;
  N1, N2, N3, Y, M, D: Word;
  L1, L2, L3, YearLen: Byte;
  CenturyBase: Integer;
  EraName : string;
  EraYearOffset: Integer;
  ............
begin
  Result := False;
  DateOrder := GetDateOrder(AFormatSettings.ShortDateFormat);
  ........
  if not (ScanNumber(S, Pos, N1, L1) and ScanChar(S, Pos, AFormatSettings.DateSeparator) and
    ScanNumber(S, Pos, N2, L2)) then Exit;
  if ScanChar(S, Pos, AFormatSettings.DateSeparator) then
  begin
    if not ScanNumber(S, Pos, N3, L3) then Exit;
    case DateOrder of
      doMDY: begin Y := N3; YearLen := L3; M := N1; D := N2; end;
      doDMY: begin Y := N3; YearLen := L3; M := N2; D := N1; end;
    else{doYMD:} begin Y := N1; YearLen := L1; M := N2; D := N3; end;
    end;
    ..........
  end else
  begin
    Y := CurrentYear;
    if DateOrder = doDMY then
    begin
      D := N1; M := N2;
    end else
    begin
      M := N1; D := N2;
    end;
  end;
  ScanChar(S, Pos, AFormatSettings.DateSeparator);
  ScanBlanks(S, Pos);
  if SysLocale.FarEast and (AFormatSettings.ShortDateFormat.Contains('dddd')) then // (System.Pos('ddd', AFormatSettings.ShortDateFormat) <> 0) then
  begin     // ignore trailing text
    ........
  end;
  Result := TryEncodeDate(Y, M, D, Date);
end;