Streak' calculation

I'm trying to create a formula that will look at the date field from the previous record, compare it to the current record, and then make a calculation based on the difference.  For example:  

If(current record date - previous record date)>1,

set field 'streak' field to (previous streak field +1)

else (set streak field to 0)

Its really a 'self link' that I'm trying to figure out.

Thanks!