shithub: femtolisp

Info  •  Files  •  Log  •  Branches

string.char: same, operate on runes rather than bytes

--- a/string.c

+++ b/string.c

@@ -209,15 +209,14 @@

 {

 	argcount(nargs, 2);

 	char *s = tostring(args[0]);

-	size_t len = cv_len(ptr(args[0]));

-	size_t i = toulong(args[1]);

-	if(i >= len)

+	size_t lenbytes = cv_len(ptr(args[0]));

+	size_t startbytes, n, startchar = toulong(args[1]);

+	for(startbytes = n = 0; n < startchar && startbytes < lenbytes; n++)

+		startbytes += u8_seqlen(s+startbytes);

+	if(n != startchar)

 		bounds_error(args[0], args[1]);

-	size_t sl = u8_seqlen(&s[i]);

-	if(sl > len || i > len-sl)

-		bounds_error(args[0], args[1]);

 	Rune r;

-	chartorune(&r, s+i);

+	chartorune(&r, s+startbytes);

 	return mk_rune(r);

 }