ReNamer:Scripts:URL decode

Decode a URL encoded filename, also known as Percent-encoding.

Note: Native URLEncode and URLDecode functions have been added in v5.74.4 Beta.

Tested

• ReNamer 5.50+ Beta

Code

Author: Denis Kozlov. Date: 4 June 2011. Derived from: DelphiDabbler URLDecode snippet

Input	Output
Ba%C5%9Fer%20Kafao%C4%9Flu.pdf	Başer Kafaoğlu.pdf
%D0%9F%D1%80%D0%B8%D0%BC%D0%B5%D1%80.doc	Пример.doc
%Invalid URL encoded name%	***ERROR***

<syntaxhighlight lang="pascal"> function URLDecode(const S: AnsiString; out Output: AnsiString): Boolean; var

 Idx: Integer;   // loops thru chars in string
 Hex: string;    // string of hex characters
 Code: Integer;  // hex character code (-1 on error)

begin

 // Intialise result and string index
 Result := False;
 Output := ;
 Idx := 1;
 // Loop thru string decoding each character
 while Idx <= Length(S) do
 begin
   case S[Idx] of
     '%':
     begin
       // % should be followed by two hex digits - exception otherwise
       if Idx <= Length(S) - 2 then
       begin
         // there are sufficient digits - try to decode hex digits
         Hex := S[Idx+1] + S[Idx+2];
         Code := StrToIntDef('$' + Hex, -1);
         Idx := Idx + 2;
       end
       else
         // insufficient digits - error
         Code := -1;
       // check for error and raise exception if found
       if Code = -1 then Exit;
       // decoded OK - add character to result
       Output := Output + Chr(Code);
     end;
     '+':
       // + is decoded as a space
       Output := Output + ' '
     else
       // All other characters pass thru unchanged
       Output := Output + S[Idx];
   end;
   Inc(Idx);
 end;
 Result := True;

end;

var

 Encoded, Decoded: AnsiString;

begin

 Encoded := WideToAnsi(FileName);
 if URLDecode(Encoded, Decoded) then
   FileName := UTF8Decode(Decoded)
 else
   FileName := '***ERROR***';

end. </source>