Merge: Fixed quick_sort when array is length 0 or 1

Fixed a bug where quick_sort could access out of bound element when `to` argument smaller or
equal to 0.

# Before

var xs = [1]
default_comparator.quick_sort(xs) # assertion failed

# After

var xs = [1]
default_comparator.quick_sort(xs)
assert xs == [1] # true

Signed-off-by: Louis-Vincent Boudreault <lv.boudreault95@gmail.com>

Pull-Request: #2811

diff --git a/lib/core/collection/sorter.nit b/lib/core/collection/sorter.nit
index 9157995..7476b6f 100644 (file)
--- a/lib/core/collection/sorter.nit
+++ b/lib/core/collection/sorter.nit
@@ -106,7 +106,14 @@ interface Comparator
        #     var a = [5, 2, 3, 1, 4]
        #     default_comparator.quick_sort(a, 0, a.length - 1)
        #     assert a == [1, 2, 3, 4, 5]
+       #     var a2 = new Array[Int]
+       #     default_comparator.quick_sort(a2, 0, a2.length - 1)
+       #     assert a2 == new Array[Int]
+       #     var a3 = [1]
+       #     default_comparator.quick_sort(a3, 0, a3.length - 1)
+       #     assert a3 == [1]
        fun quick_sort(array: Array[COMPARED], from: Int, to: Int) do
+               if from >= to then return
                var pivot = array[from]
                var i = from
                var j = to