iRule newbie - Whitelisting IP address for Spesific URL and Attack Pattern

I think it can be done, but not w/ an ASM irule. I can't write this now, as I'm sick and on quick, but the idea is to take the asm policy off the vip, then use an irule like this:

1. when http_request, check URI.
2. if uri matches [list of disallowed uris], exit the irule.
3. else, if no match, apply ASM policy.

I am going to tell you, though.. depending on traffic levels, this could get computationally expensive.