Rotate Array in Swift

Question

While exploring algorithms in Swift, couldn\'t find algorithm for array rotation in swift without using funcs shiftLeft / shiftRight.

C has

Answer 1

Edit update:

Swift 5 or later

extension RangeReplaceableCollection {
    mutating func rotateLeft(positions: Int) {
        let index = self.index(startIndex, offsetBy: positions, limitedBy: endIndex) ?? endIndex
        let slice = self[..

---

extension RangeReplaceableCollection {
    mutating func rotateRight(positions: Int) {
        let index = self.index(endIndex, offsetBy: -positions, limitedBy: startIndex) ?? startIndex
        let slice = self[index...]
        removeSubrange(index...)
        insert(contentsOf: slice, at: startIndex)
    }
}

---

var test = [1,2,3,4,5,6,7,8,9,10]
test.rotateLeft(positions: 3)   // [4, 5, 6, 7, 8, 9, 10, 1, 2, 3]

var test2 = "1234567890"
test2.rotateRight(positions: 3)   // "8901234567"