How do I find overlaps between two Ruby Runt patterns?

I am developing a Google like calendar on Rails and am using Runt to
define the recurrence patterns for creating events. However, the
restriction with the calendar is that there cannot be two events for
same time slot. So, if i have an event created with

event =,00,15,00) # daily between 1PM to 3 PM

Then the application should not allow to create another event that
overlaps this one.

Is there some way of finding whether a Runt expression overlaps with
another expression?

I came across similar question at

and the solution says that “create a DateRange object from your expr and
then run overlap”, but i am not sure how to do this. Also, what would
happen where there is no date range e.g. in the example given above
there is no start and end date.