From 0a7e90fe8e5edd548432677f8fbf3e6d1888961d Mon Sep 17 00:00:00 2001
From: parrt <parrt@cs.usfca.edu>
Date: Sat, 10 Dec 2016 14:05:31 -0800
Subject: [PATCH] fix #1177 (LB(k) stops at index 0) @antlr/antlr-targets might
 care about this

---
 runtime/Java/src/org/antlr/v4/runtime/CommonTokenStream.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/runtime/Java/src/org/antlr/v4/runtime/CommonTokenStream.java b/runtime/Java/src/org/antlr/v4/runtime/CommonTokenStream.java
index a510bc4c4e..fd6a8ebff1 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/CommonTokenStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/CommonTokenStream.java
@@ -77,7 +77,7 @@ protected Token LB(int k) {
         int i = p;
         int n = 1;
         // find k good tokens looking backwards
-        while ( n<=k ) {
+        while ( n<=k && i>0 ) {
             // skip off-channel tokens
             i = previousTokenOnChannel(i - 1, channel);
             n++;