Method parse_expr

nodedb/src/control/promql/parser.rs:63–96

Parse an expression with Pratt precedence.

(&mut self, min_prec: u8)

    /// Parse an expression with Pratt precedence.
    fn parse_expr(&mut self, min_prec: u8) -> Result<Expr, PromqlError> {
        let mut lhs = self.parse_unary()?;

        while let Some(op) = self.peek_binop() {
            if op.precedence() < min_prec {
                break;
            }
            self.advance();

            let return_bool = op.is_comparison() && self.try_keyword("bool");
            let matching = if op.is_set_op() {
                self.try_parse_set_matching()?
            } else {
                self.try_parse_vector_matching()?
            };

            let next_prec = if matches!(op, BinOp::Pow) {
                op.precedence() // right-associative
            } else {
                op.precedence() + 1
            };
            let rhs = self.parse_expr(next_prec)?;

            lhs = Expr::BinaryOp {
                op,
                lhs: Box::new(lhs),
                rhs: Box::new(rhs),
                return_bool,
                matching,
            };
        }

        Ok(lhs)
    }

    fn parse_unary(&mut self) -> Result<Expr, PromqlError> {
        if matches!(self.peek(), Token::Sub) {