General-use Quicksort in Swift

QuickSorter.swift

/// Uses quicksort with the Lomuto partition scheme.
///
/// By Ben Leggiero, written on 2018-03-05. Copyright BH-0-PD
/// https://github.com/BlueHuskyStudios/Licenses/blob/master/Licenses/BH-0-PD.txt
struct QuickSorter {
    /// Performs a quicksort with Lomuto partition using the given array and returns the result
    func quicksorting<C: Comparable>(_ unsorted: [C]) -> [C] {
        var arrayCopy = unsorted
        QuickSorter.quicksort(&arrayCopy)
        return arrayCopy
    }
    
    
    /// Performs a quicksort with Lomuto partition by mutating the given array
    static func quicksort<C: Comparable>(_ unsorted: inout [C]) {
        quicksort(&unsorted, first: 0, last: unsorted.count - 1)
    }
    
    
    /// Quicksort basic algorithm as published on Wikipedia
    /// https://en.wikipedia.org/wiki/Quicksort?oldid=827460998#Lomuto_partition_scheme
    private static func quicksort<C: Comparable>(_ array: inout [C], first: Int, last: Int) {
        if first < last {
            let p = partition(&array, first: first, last: last)
            quicksort(&array, first: first, last: p - 1)
            quicksort(&array, first: p + 1, last: last)
        }
    }
    
    
    /// Quicksort basic algorithm as published on Wikipedia
    /// https://en.wikipedia.org/wiki/Quicksort?oldid=827460998#Lomuto_partition_scheme
    private static func partition<C: Comparable>(_ array: inout [C], first: Int, last: Int) -> Int {
        let pivot = array[last]
        var i = first - 1
        for j in first..<last {
            if array[j] < pivot {
                i = i + 1
                array.swapAt(i, j)
            }
        }
        array.swapAt(i + 1, last)
        return i + 1
    }
}