nsIEnumerator

Methods

first()

First will reset the list. will return NS_FAILED if no items

next()

Next will advance the list. will return failed if already at end

currentItem()

CurrentItem will return the CurrentItem item it will fail if the
list is empty

isDone()

return if the collection is at the end. that is the beginning following
a call to Prev and it is the end of the list following a call to next