UTF ä und ß hintereinander , ß wird nicht encoded

[Schokohase]

Jupp, so dachte man sich das zu AnsiString-Zeiten auch - bis Unicode kam und das Geschrei darüber man bis heute noch hören kann.

Eventuell hilft es ja

Delphi-Quellcode:

program Rfc2047;

{$APPTYPE CONSOLE}
{$R *.res}

uses
  System.SysUtils,
  System.StrUtils,
  IdException,
  IdGlobal,
  IdCharsets,
  IdCoder,
  IdCoderQuotedPrintable,
  IdCoderMIME;

function Decode( const AStr: string; AIsHeader: Boolean = false ): string;
  function TryDecode( const encoded_str: string; out decoded_text: string ): Boolean;
  var
    parts:                         TArray<string>;
    charset, coding, encoded_text: string;
    encoding:                      IIdTextEncoding;
    coder:                         TIdDecoder;
    coderclass:                    TIdDecoderClass;
  begin
    parts := encoded_str.Split( ['?'] );

    if Length( parts ) <> 3
    then
      begin
        Exit( false );
      end;

    charset      := parts[0];
    coding       := parts[1].ToLowerInvariant( );
    encoded_text := parts[2];

    try
      encoding := IndyTextEncoding( charset );
    except
      on E: EIdException do
        begin
          Exit( false )
        end;
    end;

    if coding = 'q'
    then
      begin
        coderclass := IdCoderQuotedPrintable.TIdDecoderQuotedPrintable;
        if AIsHeader
        then
          encoded_text := encoded_text.Replace( '_', ' ' );
      end else if coding = 'b'
    then
      begin
        coderclass := IdCoderMIME.TIdDecoderMIME;
      end
    else begin
        Exit( false );
      end;

    decoded_text := coderclass.DecodeString( encoded_text, encoding );
    Result       := True;
  end;

var
  idx:    Integer;
  sp, ep: Integer;
  str:    string;
begin
  idx    := 0;
  Result := AStr;
  while True do
    begin
      sp := Result.IndexOf( '=?', idx );
      if sp < 0
      then
        break;
      ep := Result.IndexOf( '?=', sp + 2 );
      if ep < 0
      then
        break;

      if TryDecode( Result.Substring( sp + 2, ep - ( sp + 2 ) ), str )
      then
        Result := Result.Substring( 0, sp ) + str + Result.Substring( ep + 2 )
      else
        idx := ep + 2;

    end;
end;

begin

  try

    Writeln( Decode( 'Subject: =?iso-8859-1?q?this=20is=20some=20text?= =?UTF-8?Q?Planm=C3=A4=C3=9Fige_Erh=C3=B6hung_xx-xx-xx?=', True ) );

  except
    on E: Exception do
      Writeln( E.ClassName, ': ', E.Message );
  end;
  Readln;

end.