LDAP User Authentication

Is their a way to switch from local SQL based users and groups to LDAP based Users/Groups?
I noticed their is a file at  “/var/www/<home folder>/classes/runnerldap.php” which may offer a means of adapting the system to either LDAP or Active Directory based authentication. 
Could you explain the purpose of the mentioned file above, or if their is a way to make this possible?
 
Thanks!