ruby regex split on last occurance of character

Question

I'm a little stumped on this one and I'm also not still on 1.8 so I don't have lookahead.

I have a bunch of strings which can look like:

"a/b/c/d/e/f 1/2/3"

which I want to turn into:

"a/b/c/d/e" "f" "1/2" "3"

So basically I want it to split by the last slash before the beginning of whitespace. I feel like I can do this normally but split always seems to do weird things.

Answer 1

def foo s
   return [$1,$2] if s =~ /(.+)\/(\S)/
end

str = "a/b/c/d/e/f 1/2/3"
a = str.split /\s+/
a.collect { |e| foo e }.flatten

=> ["/a/b/c/d/e", "f", "1/2", "3"]

I broke down the split and collect. You could, of course, shorten this as needed.

Answer 2

1.8 lacks look*behind*, not look*ahead*! All you need is this:

str.split(/\/(?=[^\/]+(?: |$))| /)

This split pattern matches a) any slash that is followed by non-slash characters up to the next space or the end of the string, and b) any space.