Method parse_prefix_expr

src/parser.rs:369–381

(&mut self)

    }

    fn parse_prefix_expr(&mut self) -> Option<Expr> {
        let prefix = match self.current_token {
            Token::Bang => Prefix::Exclamation,
            Token::Minus => Prefix::Minus,
            Token::Plus => Prefix::Plus,
            _ => return None,
        };

        self.next_token();

        self.parse_expr(Precedence::Prefix)
            .map(|expr| Expr::Prefix(prefix, Box::new(expr)))
    }

    fn parse_infix_expr(&mut self, left: Expr) -> Option<Expr> {
        let infix = match self.current_token {