Function parser_expr_to_scalar_value_literal 

pub fn parser_expr_to_scalar_value_literal(
    expr: Expr,
    require_now_expr: bool,
) -> Result<ScalarValue>

Convert a parser expression to a scalar value. This function will try the best to resolve and reduce constants. Exprs like 1 + 1 or now() can be handled properly.

if require_now_expr is true, it will ensure that the expression contains a now() function. If the expression does not contain now(), it will return an error.