Experimental repeat() iterator for Rust

repeat_iterator.rs

// iterator.rs
pub trait IteratorUtil<A> {
    // ...
    fn repeat_(&mut self) -> RepeatIterator<A, Self>;
}

//...
    #[inline]
    fn repeat_(&mut self) -> RepeatIterator<A, T> {
        RepeatIterator{iter: self, iter_orig: copy self}
    }
//...

/// An iterator which repeats the same sequence forever, looping around
/// back to the start when it reaches the end.
pub struct RepeatIterator<A, T> {
    priv iter_orig: T,  // State of original iterator for restart
    priv iter: T,       // Current iterator
}

impl<A, T: Iterator<A>> Iterator<A> for RepeatIterator<A, T> {
    #[inline]
    fn next(&mut self) -> Option<A> {
        match self.iter.next() {
            Some(x) =>  {
                Some(x)
            }
            None => {
                self.iter = copy self.iter_orig;
                return self.next();
            }
        }
    }
}

#[cfg(test)]
mod tests {
    // ...
    #[test]
    fn test_repeat() {
        let a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
        let mut it = a.iter().repeat_();
        for uint::range(0,21) |n| {
            assert_eq!(*it.next().get(), (n%10 as int));
        }
    }
}