Add split and split_inclusive

[A4-Tacks]

Collect all iterator elements into one of two partitions.
Unlike [Iterator::partition], when predicate returns true for the first time,
it collects this element and all rest elements into B.

use itertools::Itertools;

let nums = vec![0, 1, 2, 3, 4, 5];

let (a, b): (Vec<_>, Vec<_>) = nums.into_iter().split(|n| *n == 3);

assert_eq!(a, [0, 1, 2]);
assert_eq!(b, [3, 4, 5]);

---

Collect all iterator elements into one of two partitions.
Unlike [Itertools::split], when predicate returns true, the element is collected into A

use itertools::Itertools;

let nums = vec![0, 1, 2, 3, 4, 5];

let (a, b): (Vec<_>, Vec<_>) = nums.into_iter().split_inclusive(|n| *n == 3);

assert_eq!(a, [0, 1, 2, 3]);
assert_eq!(b, [4, 5]);

[phimuemue]

Hi there. Honestly, I doubt this is really required from an API prospective, because afaik it can be expressed in terms of partition: the predicate can capture an outer bool that is flipped at the "partition point" and be returned. This "trick" might be a bit less efficient but has the advantage that it uses known functions (as opposed to the new split) - and, as a corollary, avoids the question what split should do on the second true (flip to the other container again, or ignore it).

Thus, I suggest to close this.