spans

This crate allows you to split an iterator into contiguous spans.

Import the Spans trait to extend Iterator:

use spans::Spans;

Now you can use Spans::spans_by_key to split an iterator into contiguous spans:

let vec = vec![1, 2, 5, 6, 7, 11, 13, 14, 15];
let mut spans = vec.iter().spans_by_key(|&&x| x, |a, b| a + 1 == b);

while let Some(span) = spans.next() {
    println!("span = {:?}", span.collect::<Vec<_>>());
}

The code above splits the vector into spans where each item is 1 larger than the proceeding item. The following text is printed:

span = [1, 2]
span = [5, 6, 7]
span = [11]
span = [13, 14, 15]

Many thanks to Matt Brubeck for helping me so generously on the Rust users forum.