From f64ecebd34c948432683e20e12c3cdde6429d99f Mon Sep 17 00:00:00 2001
From: sharwell <sharwell@pixelminegames.com>
Date: Fri, 18 Nov 2011 22:54:07 -0800
Subject: [PATCH] v4: Fix LookaheadStream ability to seek forward past the
 current location (via consume())

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 9395]
---
 .../org/antlr/v4/runtime/misc/LookaheadStream.java   | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/runtime/Java/src/org/antlr/v4/runtime/misc/LookaheadStream.java b/runtime/Java/src/org/antlr/v4/runtime/misc/LookaheadStream.java
index 8178f2fec..aeaa85720 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/misc/LookaheadStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/misc/LookaheadStream.java
@@ -145,12 +145,18 @@ public abstract class LookaheadStream<T> extends FastQueue<T> {
      */
     public void seek(int index) {
         int bufferStartIndex = currentElementIndex - p;
-        if (index < bufferStartIndex || index > currentElementIndex) {
+        if (index < bufferStartIndex) {
             throw new UnsupportedOperationException("Cannot seek to the specified index.");
         }
 
-        currentElementIndex = index;
-        p = index - bufferStartIndex;
+        if (index > currentElementIndex) {
+            for (int i = 0; i < currentElementIndex - index; i++) {
+                consume();
+            }
+        } else {
+            currentElementIndex = index;
+            p = index - bufferStartIndex;
+        }
     }
 
     protected T LB(int k) {