Hide by Regex Pattern?

Would it be expensive/difficult to implement hiding by pattern?

Say, an account can have up to some reasonable number of patterns.

In the profile, they could appear in a simple multi-line text field. Any nonblank line is a pattern. A checkbox next to this controls whether it is turned on and off.

Any title matching any of the patterns is hidden. If a pattern starts with url: it applies to the URL domain rather than title. Remove a pattern and everything that is only hidden by that pattern is unhidden.

Disable pattern hiding by clearing the checkbox, and everything hidden by patterns appears.