[Oberon] Username which contains the "@" char ...

[jan verhoeven]

Op Thursday 05 January 2006 21:49 schreef shark at gulfnet.sd64.bc.ca:

 > "http://carnot.pathology.ubc.ca/pe.RFC2396.Mod" => pe.RFC2396.Mod ~

Some comments from a nitpicker, which might work and perhaps not. My 
experience with Oberon is yet minimal. I do mostly Modula-2.

-------------------------------------------

	PROCEDURE HexVal(ch: CHAR): INTEGER;
	BEGIN
		IF (ch >= "0") & (ch <= "9") THEN
			RETURN ORD(ch)-ORD("0")
		ELSIF (ch >= "A") & (ch <= "F") THEN
			RETURN ORD(ch)-ORD("A")+10
		ELSIF (ch >= "a") & (ch <= "f") THEN
			RETURN ORD(ch)-ORD("a")+10
		END
	END HexVal;

mine:

	PROCEDURE HexVal(ch: CHAR): INTEGER;
	BEGIN
		ch := CAP (ch);
		IF (ch >= "0") & (ch <= "9") THEN
			RETURN ORD(ch)-ORD("0")
		ELSIF (ch >= "A") & (ch <= "F") THEN
			RETURN ORD(ch)-ORD("A")+10
		END
	END HexVal;

-------------------------------------------

	PROCEDURE LogChars(s: ARRAY OF CHAR);
	VAR i: LONGINT;
	BEGIN
		i := 0;
    	WHILE ~((i = LEN(s)) OR (s[i] = 0X)) DO 
	   Texts.Write(W, s[i]); 
	   INC(i) 
	END;
	END LogChars;

mine:

	PROCEDURE LogChars(s: ARRAY OF CHAR);
	VAR i: LONGINT;
	BEGIN
		i := 0;
    	WHILE (i < LEN(s)) AND (s[i] # 0X) DO 
	   Texts.Write(W, s[i]); 
	   INC(i) 
	END;
	END LogChars;

Complex negations are not easy to read.

-------------------------------------------

	PROCEDURE HexDigit(i: INTEGER): CHAR;
	BEGIN
		IF i < 10 THEN
			RETURN CHR(i+ORD("0"))
		ELSE
			RETURN CHR(i-10+ORD("A"))
		END
	END HexDigit;

mine:

	PROCEDURE HexDigit(i: INTEGER): CHAR;
	BEGIN
	   RETURN HexDigs [i];
	END HexDigit;

Where HexDigs = "0123456789ABCDEF"

-------------------------------------------

	ELSIF (source[is] = "%") & Strings.IsHexDigit(source[is+1])
		& Strings.IsHexDigit(source[is+2]) THEN INC(is); INC(is)
	(* ELSE literal character *)

mine:

	ELSIF (source[is] = "%") & Strings.IsHexDigit(source[is+1])
		& Strings.IsHexDigit(source[is+2]) THEN INC(is, 2)
	(* ELSE literal character *)

Question: what happens when someone enters '%GG' in the string? The 
condition will be false, so the conversion will not be carried out. But 
also the indexes are not incremented. Hence the '%' is stripped but the 
'GG' part remains in the string. Is this the meaning?

-------------------------------------------

PROCEDURE RequiresEscape(ch:CHAR):BOOLEAN;
BEGIN
	IF (ch = 0X)
	THEN
		RETURN(FALSE)
	ELSIF (ch <= 020X) OR (ch = "+") OR (ch = "&") OR (ch = "=") OR (ch = "?")
		OR (ch = "%") OR (ch = "$") OR (ch = ";") OR (ch = "#") OR (ch = ":")
		OR (ch = special)
	THEN
		RETURN(TRUE)
	ELSE
		RETURN(FALSE)
	END
END RequiresEscape;

mine:

TYPE  SpecalChar = ('+', '&', '=', '?', '%', '$', ';', '#', ':');
      SpecialCharSet = SET OF SpecialChar;

PROCEDURE RequiresEscape(ch:CHAR):BOOLEAN;
BEGIN
	IF (ch = 0X)
	THEN
	   RETURN(FALSE)
	ELSIF  (ch <= 020X) OR (ch IN SpecialCharSet OR (ch = special)  THEN
	   RETURN(TRUE)
	ELSE
	   RETURN(FALSE)
	END
END RequiresEscape;

-------------------------------------------

ELSIF RequiresEscape(source[is]) THEN INC(it); INC(it); INC(it); INC(is)

mine:

ELSIF RequiresEscape(source[is]) THEN INC(it, 3); INC(is)

If you forget one INC (it) you're in for a surprise.

-------------------------------------------

IF it < tlen THEN (* The escaped version will fit into the target array. *)
ELSE
	INC(errors);
	LogString("RFC2396.ESC.ESC1: Escaped version of string "); LogLn;
	Log(22X); LogString(source); Log(22X); LogLn;
	LogString("will be too long for the array.  Not escaping."); LogLn;
	RETURN
END;

THEN what? If only the ELSE is needed, why not invert the Boolean 
expression?

-------------------------------------------

I think you are overcomplicating things with the backward fill/conversion 
cycle. It doesn't really matter if you do a normal fill/conversion. Your 
method is slightly easier to code due to the filling with HexDigits.

-------------------------------------------

-- 
Met vriendelijke groeten

Jan Verhoeven
http://fruttenboel.verhoeven272.nl