shithub: femtolisp

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string.sub: make indexes point to runes, doing so with bytes is kinda useless

--- a/string.c

+++ b/string.c

@@ -184,22 +184,24 @@

 	if(nargs != 2)

 		argcount(nargs, 3);

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

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

-	size_t i1, i2;

-	i1 = toulong(args[1]);

-	if(i1 > len)

+	size_t lenbytes = cv_len((cvalue_t*)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 endbytes = lenbytes;

 	if(nargs == 3){

-		i2 = toulong(args[2]);

-		if(i2 > len)

+		size_t endchar = toulong(args[2]);

+		for(endbytes = startbytes; n < endchar && endbytes < lenbytes; n++)

+			endbytes += u8_seqlen(s+endbytes);

+		if(n != endchar)

 			bounds_error(args[0], args[2]);

-	}else{

-		i2 = len;

 	}

-	if(i2 <= i1)

-		return cvalue_string(0);

-	value_t ns = cvalue_string(i2-i1);

-	memmove(cv_data((cvalue_t*)ptr(ns)), &s[i1], i2-i1);

+	if(endbytes == startbytes)

+		return symbol_value(emptystringsym);

+	value_t ns = cvalue_string(endbytes-startbytes);

+	memmove(cv_data(ptr(ns)), s+startbytes, endbytes-startbytes);

 	return ns;

 }