From 2957c2d05e8d8574e457e4be59f26775993bb9c8 Mon Sep 17 00:00:00 2001
From: Maxim Shafirov <max@jetbrains.com>
Date: Thu, 16 Dec 2010 15:37:14 +0300
Subject: [PATCH] Lookahead is now aware of whitespace and comment tokens that
 should not be count

---
 .../src/com/intellij/lang/impl/PsiBuilderImpl.java  | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/platform/lang-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java b/platform/lang-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java
index 522c70575b82..5d9f5e95ea24 100644
--- a/platform/lang-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java
+++ b/platform/lang-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java
@@ -620,8 +620,17 @@ public class PsiBuilderImpl extends UserDataHolderBase implements PsiBuilder {
   @Nullable
   @Override
   public IElementType lookAhead(int steps) {
-    if (steps + myCurrentLexeme >= myLexemeCount) return null;
-    return myLexTypes[myCurrentLexeme + steps];
+    int cur = myCurrentLexeme;
+
+    while (steps > 0) {
+      while (cur < myLexemeCount && whitespaceOrComment(myLexTypes[cur])) {
+        cur++;
+      }
+
+      steps--;
+    }
+
+    return cur < myLexemeCount ? myLexTypes[cur] : null;
   }
 
   @Override