An expression evaluation system is provided. During operation, the system can obtain an encoded expression associated with a user group of a network and evaluate the encoded expression for a first switch to determine a first set of commands that the user group is allowed to execute on the first switch. The encoded expression can encode a set of commands. The system can then determine validity of the first set of commands for the user group by determining whether a respective user of the user group should be allowed to execute the first set of commands on the first switch. If the system identifies an issue with the validity of the first set commands, the system can generate a notification indicating the issue.