}
	}
}

// factor = const | '+' factor | '-' factor | '~' factor | '(' expr ')'
func (p *Parser) factor() uint64 {
	tok := p.next()
	switch tok.ScanToken {
	case scanner.Int:
		return p.atoi(tok.String())
	case scanner.Char:
		str, err := strconv.Unquote(tok.String())
		if err != nil {
			p.errorf("%s", err)
		}
		r, w := utf8.DecodeRuneInString(str)
		if w == 1 && r == utf8.RuneError {