From 18840e36df83bd221ff2d7de8e2cc0988f2eedcb Mon Sep 17 00:00:00 2001
From: Francisco Castro <fcr@adinet.com.uy>
Date: Tue, 16 May 2017 23:16:34 -0300
Subject: [PATCH] Fix bug #40: string.sub broken for j=0 or j<i

---
 vm/src/lib.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/vm/src/lib.js b/vm/src/lib.js
index f95f116..20ef0b0 100644
--- a/vm/src/lib.js
+++ b/vm/src/lib.js
@@ -1924,7 +1924,7 @@
 			if (typeof s != 'string' && typeof s != 'number') throw new shine.Error("Bad argument #1 to 'sub' (string expected, got " + typeof s + ")");
 			s = '' + s;
 			i = i || 1;
-			j = j || s.length;
+			if (j === undefined) j = s.length;
 			
 			if (i > 0) {
 				i = i - 1;
@@ -1933,6 +1933,7 @@
 			}
 			
 			if (j < 0) j = s.length + j + 1;
+			if (i > j) return '';
 			
 			return s.substring(i, j);
 		},