ActionScript 3.0 :: Check For New Entry In Set?

I need to find the new item in a new set that is not in an existing set. here is an example:

// current set
{file, file, file, file, file}
// new set
{file, file, file, file, file, file}

- The current set contains a list of file objects (for example)

- The new set contains another set of file objects, however it contains most of the same files in the current set, but now includes a brand new file.The new file in the new set needs to be pushed onto the current set.

Restrictions:

- The new set cannot replace the current set, only the new file can be appended.

- The files cannot be directly compared because each file in the new set that references the same file as a reference in the current set is not the same instance. Therefore they need to be compared by property, in this case, teh file name.I have the general work out of the algorithm:

actionscript Code:

for each(var currentFile:FileInfo in currentSet) {  for each(var newFile:LocalFileInfo in newSet) { if(newFile.name == currentFile.name) { }}

But i just cant work out how to extract the new file. I will get it eventually, but im kinda hoping that someone will find a better solution entirely. one that might not even require so many loops.