QuickSortList.applescript

use AppleScript version "2.4" -- Yosemite (10.10) or later
use scripting additions

-- ListHandlers

on listSort(L)
	return quicksort(L, 1, count L)
end listSort

on quicksort(L, leftIndex, rightIndex)
	if L = {} then return L
	
	set lHold to leftIndex
	set rHold to rightIndex
	
	set pivot to item leftIndex of L
	
	repeat while leftIndex < rightIndex
		repeat while item rightIndex of L ≥ pivot and leftIndex < rightIndex
			set rightIndex to rightIndex - 1
		end repeat
		
		if leftIndex is not equal to rightIndex then
			set item leftIndex of L to item rightIndex of L
			set leftIndex to leftIndex + 1
		end if
		
		repeat while item leftIndex of L ≤ pivot and leftIndex < rightIndex
			set leftIndex to leftIndex + 1
		end repeat
		
		if leftIndex is not equal to rightIndex then
			set item rightIndex of L to item leftIndex of L
			set rightIndex to rightIndex - 1
		end if
	end repeat
	
	set item leftIndex of L to pivot
	set oldLeft to leftIndex
	set leftIndex to lHold
	set rightIndex to rHold
	
	if leftIndex < oldLeft then
		quicksort(L, oldLeft + 1, rightIndex)
	end if
	
	return L
end quicksort