Matching server host name in location directive

[Quintin Par]

 Can someone help me answer this question at
  serverfault.com<http://serverfault.com/questions/286828/nginx-matching-server-host-name-in-location-directive>?

-------
  Posted again

  I have nginx running multiple domains under a single server directive as
  server {
          listen       80;
          server_name  www.domain.com;
          server_name  x.domain.com;
          server_name  y.domain.com;
  ----
  ----
  ----
  }

  Now, I need to use location directive to match a subdomain and apply basic
  auth to it. The equivalent of

  location x.domain.com {
          auth_basic "Admin Login";
         auth_basic_user_file /etc/nginx/.htpasswd;
  }

  How do I do this using DRY?