Implemented quicksort in _sort()

test/scripts/lib/compound.toy

@@ -228,6 +228,33 @@ import compound;
 }
 
 
+//test sort
+{
+	fn less(a, b) {
+		return a < b;
+	}
+
+	fn greater(a, b) {
+		return a > b;
+	}
+
+	var a = [7, 2, 1, 8, 6, 3, 5, 4];
+	var b = [7, 2, 1, 4, 6, 3, 5, 8];
+	var c = [1, 2, 3, 4, 5, 6, 7, 8];
+	var d = [7, 2, 1, 8, 6, 3, 5, 4];
+
+	a = a.sort(less);
+	b = b.sort(less);
+	c = c.sort(less);
+	d = d.sort(greater);
+
+	assert a == [1, 2, 3, 4, 5, 6, 7, 8], "array.sort(less) failed";
+	assert b == [1, 2, 3, 4, 5, 6, 7, 8], "array.sort(less) with pivot high failed";
+	assert c == [1, 2, 3, 4, 5, 6, 7, 8], "array.sort(less) pre-sorted array failed";
+	assert d == [8, 7, 6, 5, 4, 3, 2, 1], "array.sort(greater) failed";
+}
+
+
 //test toLower
 {
 	assert "Hello World".toLower() == "hello world", "_toLower() failed";