dateutil.pas

RX Library contains a large number of components, objects and routines for Borland Delphi with full

end;

{ String to date conversions. Copied from SYSUTILS.PAS unit. }

procedure ScanBlanks(const S: string; var Pos: Integer);
var
  I: Integer;
begin
  I := Pos;
  while (I <= Length(S)) and (S[I] = ' ') do Inc(I);
  Pos := I;
end;

function ScanNumber(const S: string; MaxLength: Integer; var Pos: Integer;
  var Number: Longint): Boolean;
var
  I: Integer;
  N: Word;
begin
  Result := False;
  ScanBlanks(S, Pos);
  I := Pos;
  N := 0;
  while (I <= Length(S)) and (Longint(I - Pos) < MaxLength) and
    (S[I] in ['0'..'9']) and (N < 1000) do
  begin
    N := N * 10 + (Ord(S[I]) - Ord('0'));
    Inc(I);
  end;
  if I > Pos then begin
    Pos := I;
    Number := N;
    Result := True;
  end;
end;

function ScanChar(const S: string; var Pos: Integer; Ch: Char): Boolean;
begin
  Result := False;
  ScanBlanks(S, Pos);
  if (Pos <= Length(S)) and (S[Pos] = Ch) then begin
    Inc(Pos);
    Result := True;
  end;
end;

{$IFDEF RX_D3}
procedure ScanToNumber(const S: string; var Pos: Integer);
begin
  while (Pos <= Length(S)) and not (S[Pos] in ['0'..'9']) do begin
    if S[Pos] in LeadBytes then Inc(Pos);
    Inc(Pos);
  end;
end;
{$ENDIF}

function GetDateOrder(const DateFormat: string): TDateOrder;
var
  I: Integer;
begin
  Result := DefaultDateOrder;
  I := 1;
  while I <= Length(DateFormat) do begin
    case Chr(Ord(DateFormat[I]) and $DF) of
{$IFDEF RX_D3}
      'E': Result := doYMD;
{$ENDIF}
      'Y': Result := doYMD;
      'M': Result := doMDY;
      'D': Result := doDMY;
    else
      Inc(I);
      Continue;
    end;
    Exit;
  end;
  Result := DefaultDateOrder; { default }
end;

function ExpandYear(Year: Integer): Integer;
var
  N: Longint;
begin
  Result := Year;
  if Result < 100 then begin
    N := CurrentYear - CenturyOffset;
    Inc(Result, N div 100 * 100);
    if (CenturyOffset > 0) and (Result < N) then
      Inc(Result, 100);
  end;
end;

function ScanDate(const S, DateFormat: string; var Pos: Integer;
  var Y, M, D: Integer): Boolean;
var
  DateOrder: TDateOrder;
  N1, N2, N3: Longint;
begin
  Result := False;
  Y := 0; M := 0; D := 0;
  DateOrder := GetDateOrder(DateFormat);
{$IFDEF RX_D3}
  if ShortDateFormat[1] = 'g' then { skip over prefix text }
    ScanToNumber(S, Pos);
{$ENDIF RX_D3}
  if not (ScanNumber(S, MaxInt, Pos, N1) and ScanChar(S, Pos, DateSeparator) and
    ScanNumber(S, MaxInt, Pos, N2)) then Exit;
  if ScanChar(S, Pos, DateSeparator) then begin
    if not ScanNumber(S, MaxInt, Pos, N3) then Exit;
    case DateOrder of
      doMDY: begin Y := N3; M := N1; D := N2; end;
      doDMY: begin Y := N3; M := N2; D := N1; end;
      doYMD: begin Y := N1; M := N2; D := N3; end;
    end;
    Y := ExpandYear(Y);
  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, DateSeparator);
  ScanBlanks(S, Pos);
{$IFDEF RX_D3}
  if SysLocale.FarEast and (System.Pos('ddd', ShortDateFormat) <> 0) then
  begin { ignore trailing text }
    if ShortTimeFormat[1] in ['0'..'9'] then  { stop at time digit }
      ScanToNumber(S, Pos)
    else  { stop at time prefix }
      repeat
        while (Pos <= Length(S)) and (S[Pos] <> ' ') do Inc(Pos);
        ScanBlanks(S, Pos);
      until (Pos > Length(S)) or
        (AnsiCompareText(TimeAMString, Copy(S, Pos, Length(TimeAMString))) = 0) or
        (AnsiCompareText(TimePMString, Copy(S, Pos, Length(TimePMString))) = 0);
  end;
{$ENDIF RX_D3}
  Result := IsValidDate(Y, M, D) and (Pos > Length(S));
end;

function MonthFromName(const S: string; MaxLen: Byte): Byte;
begin
  if Length(S) > 0 then
    for Result := 1 to 12 do begin
      if (Length(LongMonthNames[Result]) > 0) and
        (AnsiCompareText(Copy(S, 1, MaxLen),
        Copy(LongMonthNames[Result], 1, MaxLen)) = 0) then Exit;
    end;
  Result := 0;
end;

procedure ExtractMask(const Format, S: string; Ch: Char; Cnt: Integer;
  var I: Integer; Blank, Default: Integer);
var
  Tmp: string[20];
  J, L: Integer;
begin
  I := Default;
  Ch := UpCase(Ch);
  L := Length(Format);
  if Length(S) < L then L := Length(S)
  else if Length(S) > L then Exit;
  J := Pos(MakeStr(Ch, Cnt), AnsiUpperCase(Format));
  if J <= 0 then Exit;
  Tmp := '';
  while (UpCase(Format[J]) = Ch) and (J <= L) do begin
    if S[J] <> ' ' then Tmp := Tmp + S[J];
    Inc(J);
  end;
  if Tmp = '' then I := Blank
  else if Cnt > 1 then begin
    I := MonthFromName(Tmp, Length(Tmp));
    if I = 0 then I := -1;
  end
  else I := StrToIntDef(Tmp, -1);
end;

function ScanDateStr(const Format, S: string; var D, M, Y: Integer): Boolean;
var
  Pos: Integer;
begin
  ExtractMask(Format, S, 'm', 3, M, -1, 0); { short month name? }
  if M = 0 then ExtractMask(Format, S, 'm', 1, M, -1, 0);
  ExtractMask(Format, S, 'd', 1, D, -1, 1);
  ExtractMask(Format, S, 'y', 1, Y, -1, CurrentYear);
  Y := ExpandYear(Y);
  Result := IsValidDate(Y, M, D);
  if not Result then begin
    Pos := 1;
    Result := ScanDate(S, Format, Pos, Y, M, D);
  end;
end;

function InternalStrToDate(const DateFormat, S: string;
  var Date: TDateTime): Boolean;
var
  D, M, Y: Integer;
begin
  if S = '' then begin
    Date := NullDate;
    Result := True;
  end
  else begin
    Result := ScanDateStr(DateFormat, S, D, M, Y);
    if Result then
    try
      Date := EncodeDate(Y, M, D);
    except
      Result := False;
    end;
  end;
end;

function StrToDateFmt(const DateFormat, S: string): TDateTime;
begin
  if not InternalStrToDate(DateFormat, S, Result) then
    raise EConvertError.CreateFmt({$IFDEF RX_D3} SInvalidDate {$ELSE}
      LoadStr(SInvalidDate) {$ENDIF}, [S]);
end;

function StrToDateDef(const S: string; Default: TDateTime): TDateTime;
begin
  if not InternalStrToDate(ShortDateFormat, S, Result) then
    Result := Trunc(Default);
end;

function StrToDateFmtDef(const DateFormat, S: string; Default: TDateTime): TDateTime;
begin
  if not InternalStrToDate(DateFormat, S, Result) then
    Result := Trunc(Default);
end;

function DefDateFormat(FourDigitYear: Boolean): string;
begin
  if FourDigitYear then begin
    case GetDateOrder(ShortDateFormat) of
      doMDY: Result := 'MM/DD/YYYY';
      doDMY: Result := 'DD/MM/YYYY';
      doYMD: Result := 'YYYY/MM/DD';
    end;
  end
  else begin
    case GetDateOrder(ShortDateFormat) of
      doMDY: Result := 'MM/DD/YY';
      doDMY: Result := 'DD/MM/YY';
      doYMD: Result := 'YY/MM/DD';
    end;
  end;
end;

function DefDateMask(BlanksChar: Char; FourDigitYear: Boolean): string;
begin
  if FourDigitYear then begin
    case GetDateOrder(ShortDateFormat) of
      doMDY, doDMY: Result := '!99/99/9999;1;';
      doYMD: Result := '!9999/99/99;1;';
    end;
  end
  else begin
    case GetDateOrder(ShortDateFormat) of
      doMDY, doDMY: Result := '!99/99/99;1;';
      doYMD: Result := '!99/99/99;1;';
    end;
  end;
  if Result <> '' then Result := Result + BlanksChar;
end;

{$IFDEF WIN32}

function FormatLongDate(Value: TDateTime): string;
var
  Buffer: array[0..1023] of Char;
  SystemTime: TSystemTime;
begin
{$IFDEF RX_D3}
  DateTimeToSystemTime(Value, SystemTime);
{$ELSE}
  with SystemTime do begin
    DecodeDate(Value, wYear, wMonth, wDay);
    DecodeTime(Value, wHour, wMinute, wSecond, wMilliseconds);
  end;
{$ENDIF}
  SetString(Result, Buffer, GetDateFormat(GetThreadLocale, DATE_LONGDATE,
    @SystemTime, nil, Buffer, SizeOf(Buffer) - 1));
  Result := TrimRight(Result);
end;

function FormatLongDateTime(Value: TDateTime): string;
begin
  if Value <> NullDate then
    Result := FormatLongDate(Value) + FormatDateTime(' tt', Value)
  else Result := '';
end;

{$ENDIF WIN32}

{$IFNDEF USE_FOUR_DIGIT_YEAR}
function FourDigitYear: Boolean;
begin
  Result := Pos('YYYY', AnsiUpperCase(ShortDateFormat)) > 0;
end;
{$ENDIF}

{$IFDEF USE_FOUR_DIGIT_YEAR}
initialization
  FourDigitYear := Pos('YYYY', AnsiUpperCase(ShortDateFormat)) > 0;
{$ENDIF}
end.