// encoding/utf8 — UTF-8 helpers. RFC 3629; we only handle the legal
// subset (no over-long encodings, no surrogates).

def MAX:  rune = 1114111;	// 0x10FFFF

// runesz — encoded byte length of `r` as UTF-8. void variant means
// `r` is outside the legal range (negative, > 0x10FFFF).
export fn runesz(r: rune) (i32 | void) = {
	if (r < 0)         { return; };
	if (r < 128)       { return 1; };
	if (r < 2048)      { return 2; };
	if (r < 65536)     { return 3; };
	if (r <= MAX)      { return 4; };
	return;
};