From 98022f93823f04bab6eeb0840af421268c9a2e59 Mon Sep 17 00:00:00 2001
From: hybfkuf <fredjoseph863@gmail.com>
Date: Sun, 20 Aug 2023 06:34:07 +0800
Subject: [PATCH] bugfix: make sure the value of x2 is greater than x1. (#50)

Co-authored-by: hybfkuf <hybfkuf@hybfkufs-MacBook-Pro.local>
---
 array2d/array2d.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/array2d/array2d.go b/array2d/array2d.go
index db09fc7..172283c 100644
--- a/array2d/array2d.go
+++ b/array2d/array2d.go
@@ -131,6 +131,9 @@ func (a Array2D[T]) RowSpan(x1, x2, y int) []T {
 	if x2 < 0 || x2 >= a.width {
 		panic(fmt.Sprintf("array2d: x2 index out of range [%d] with width %d", x2, a.width))
 	}
+	if x2 < x1 {
+		x1, x2 = x2, x1
+	}
 	return a.slice[x1+y*a.height : 1+x2+y*a.height]
 }