diff --git a/RegExpSupport/src/org/intellij/lang/regexp/RegExpLanguageHost.java b/RegExpSupport/src/org/intellij/lang/regexp/RegExpLanguageHost.java
index ff3de43a5fde..7628f30aae1d 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/RegExpLanguageHost.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/RegExpLanguageHost.java
@@ -5,4 +5,5 @@ package org.intellij.lang.regexp;
  */
 public interface RegExpLanguageHost {
   boolean characterNeedsEscaping(char c);
+  boolean supportsPerl5EmbeddedComments();
 }
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/_RegExLexer.java b/RegExpSupport/src/org/intellij/lang/regexp/_RegExLexer.java
index 74b7fc2f7523..908f634854cf 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/_RegExLexer.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/_RegExLexer.java
@@ -1,4 +1,4 @@
-/* The following code was generated by JFlex 1.4.1 on 13.03.09 16:25 */
+/* The following code was generated by JFlex 1.4.1 on 23.09.09 18:11 */
 
 /* It's an automatically generated code. Do not modify it. */
 package org.intellij.lang.regexp;
@@ -14,8 +14,8 @@ import com.intellij.psi.StringEscapesTokenTypes;
 /**
  * This class is a scanner generated by 
  * <a href="http://www.jflex.de/">JFlex</a> 1.4.1
- * on 13.03.09 16:25 from the specification file
- * <tt>C:/work/java/idea-plugins/RegExpSupport/Trunk/src/org/intellij/lang/regexp/regexp-lexer.flex</tt>
+ * on 23.09.09 18:11 from the specification file
+ * <tt>C:/JetBrains/IDEA/svnPlugins/RegExpSupport/src/org/intellij/lang/regexp/regexp-lexer.flex</tt>
  */
 class _RegExLexer implements FlexLexer {
   /** initial size of the lookahead buffer */
@@ -121,12 +121,12 @@ class _RegExLexer implements FlexLexer {
     "\1\36\1\35\1\37\1\40\1\1\1\41\1\42\1\2"+
     "\1\43\1\44\1\45\1\46\1\47\1\50\1\51\1\52"+
     "\1\53\2\54\1\55\1\11\1\56\1\57\1\60\1\61"+
-    "\1\62\1\63\1\64\1\65\1\0\1\66\1\67\2\57"+
-    "\2\60\1\70\1\71\1\66\1\57\1\72\2\60\1\66"+
-    "\3\60\1\73";
+    "\1\62\1\63\1\64\1\65\2\0\1\66\1\67\2\57"+
+    "\2\60\1\70\1\71\1\0\1\66\1\57\1\72\2\60"+
+    "\1\73\1\66\3\60\1\74";
 
   private static int [] zzUnpackAction() {
-    int [] result = new int[85];
+    int [] result = new int[88];
     int offset = 0;
     offset = zzUnpackAction(ZZ_ACTION_PACKED_0, offset, result);
     return result;
@@ -159,12 +159,12 @@ class _RegExLexer implements FlexLexer {
     "\0\u0188\0\u0310\0\u0341\0\u0188\0\u0188\0\u0372\0\u0188\0\u0188"+
     "\0\u03a3\0\u03d4\0\u0188\0\u0188\0\u0188\0\u0188\0\u0188\0\u0405"+
     "\0\u0188\0\u0188\0\u0188\0\u0436\0\u0467\0\u0188\0\u0188\0\u0188"+
-    "\0\u0188\0\u0188\0\u0498\0\u04c9\0\u0188\0\u04fa\0\u052b\0\u055c"+
-    "\0\u058d\0\u0188\0\u0188\0\u05be\0\u0188\0\u0188\0\u05ef\0\u0620"+
-    "\0\u0188\0\u0651\0\u0682\0\u0188\0\u0188";
+    "\0\u0188\0\u0188\0\u0498\0\u04c9\0\u04fa\0\u0188\0\u052b\0\u055c"+
+    "\0\u058d\0\u05be\0\u0188\0\u0188\0\u05ef\0\u0620\0\u0188\0\u0188"+
+    "\0\u0651\0\u0682\0\u0188\0\u0188\0\u06b3\0\u06e4\0\u0188\0\u0188";
 
   private static int [] zzUnpackRowMap() {
-    int [] result = new int[85];
+    int [] result = new int[88];
     int offset = 0;
     offset = zzUnpackRowMap(ZZ_ROWMAP_PACKED_0, offset, result);
     return result;
@@ -205,22 +205,23 @@ class _RegExLexer implements FlexLexer {
     "\1\34\3\0\1\34\14\0\2\36\17\0\20\36\1\0"+
     "\3\36\62\0\1\77\33\0\17\52\2\0\1\52\37\0"+
     "\17\53\2\0\1\53\66\0\2\100\1\101\1\102\1\103"+
-    "\4\0\2\61\36\0\1\61\21\0\1\104\36\0\1\104"+
-    "\17\0\61\105\1\106\2\107\20\106\2\107\2\106\3\107"+
-    "\2\106\1\107\1\106\1\107\2\106\1\107\17\106\1\110"+
-    "\2\111\20\110\2\111\2\110\3\111\2\110\1\111\1\110"+
-    "\1\111\2\110\1\111\17\110\53\0\1\112\1\113\6\0"+
-    "\1\114\36\0\1\114\17\0\62\115\2\116\20\115\2\116"+
-    "\2\115\3\116\2\115\1\116\1\115\1\116\2\115\1\116"+
-    "\17\115\62\117\2\120\20\117\2\120\2\117\3\120\2\117"+
-    "\1\120\1\117\1\120\2\117\1\120\17\117\2\0\1\121"+
-    "\36\0\1\121\17\0\62\122\2\123\20\122\2\123\2\122"+
-    "\3\123\2\122\1\123\1\122\1\123\2\122\1\123\17\122"+
-    "\62\124\2\125\20\124\2\125\2\124\3\125\2\124\1\125"+
-    "\1\124\1\125\2\124\1\125\17\124";
+    "\1\104\3\0\2\61\36\0\1\61\21\0\1\105\36\0"+
+    "\1\105\17\0\61\106\1\107\2\110\20\107\2\110\2\107"+
+    "\3\110\2\107\1\110\1\107\1\110\2\107\1\110\17\107"+
+    "\1\111\2\112\20\111\2\112\2\111\3\112\2\111\1\112"+
+    "\1\111\1\112\2\111\1\112\17\111\53\0\1\113\1\114"+
+    "\4\0\5\115\1\0\53\115\2\0\1\116\36\0\1\116"+
+    "\17\0\62\117\2\120\20\117\2\120\2\117\3\120\2\117"+
+    "\1\120\1\117\1\120\2\117\1\120\17\117\62\121\2\122"+
+    "\20\121\2\122\2\121\3\122\2\121\1\122\1\121\1\122"+
+    "\2\121\1\122\17\121\5\115\1\123\53\115\2\0\1\124"+
+    "\36\0\1\124\17\0\62\125\2\126\20\125\2\126\2\125"+
+    "\3\126\2\125\1\126\1\125\1\126\2\125\1\126\17\125"+
+    "\62\127\2\130\20\127\2\130\2\127\3\130\2\127\1\130"+
+    "\1\127\1\130\2\127\1\130\17\127";
 
   private static int [] zzUnpackTrans() {
-    int [] result = new int[1715];
+    int [] result = new int[1813];
     int offset = 0;
     offset = zzUnpackTrans(ZZ_TRANS_PACKED_0, offset, result);
     return result;
@@ -264,11 +265,12 @@ class _RegExLexer implements FlexLexer {
     "\6\0\2\1\2\11\1\1\2\11\1\3\1\1\12\11"+
     "\1\1\1\11\1\1\1\11\1\1\5\11\1\1\2\11"+
     "\1\3\2\11\2\1\2\11\1\1\1\15\1\11\2\1"+
-    "\5\11\1\1\3\11\2\1\5\11\1\0\1\1\1\11"+
-    "\4\1\2\11\1\1\2\11\2\1\1\11\2\1\2\11";
+    "\5\11\1\1\3\11\2\1\5\11\2\0\1\1\1\11"+
+    "\4\1\2\11\1\0\1\1\2\11\2\1\2\11\2\1"+
+    "\2\11";
 
   private static int [] zzUnpackAttribute() {
-    int [] result = new int[85];
+    int [] result = new int[88];
     int offset = 0;
     offset = zzUnpackAttribute(ZZ_ATTRIBUTE_PACKED_0, offset, result);
     return result;
@@ -413,7 +415,14 @@ class _RegExLexer implements FlexLexer {
 
   // For Demetra compatibility
   public void reset(CharSequence buffer, int initialState){
-    reset(buffer, 0, buffer.length(), initialState);
+    zzBuffer = buffer;
+    zzBufferArray = null; 
+    zzCurrentPos = zzMarkedPos = zzStartRead = 0;
+    zzPushbackPos = 0;
+    zzAtEOF = false;
+    zzAtBOL = true;
+    zzEndRead = buffer.length();
+    yybegin(initialState);
   }
 
   /**
@@ -625,239 +634,243 @@ class _RegExLexer implements FlexLexer {
         case 7: 
           { if (yystate() != CLASS2) yypushstate(EMBRACED); return RegExpTT.LBRACE;
           }
-        case 60: break;
+        case 61: break;
         case 6: 
           { return RegExpTT.GROUP_END;
           }
-        case 61: break;
+        case 62: break;
         case 36: 
           { yypushstate(CLASS1); return RegExpTT.CLASS_BEGIN;
           }
-        case 62: break;
+        case 63: break;
         case 14: 
           { return RegExpTT.STAR;
           }
-        case 63: break;
+        case 64: break;
         case 40: 
           { return RegExpTT.ESC_CHARACTER;
           }
-        case 64: break;
+        case 65: break;
         case 28: 
           { return commentMode ? com.intellij.psi.TokenType.WHITE_SPACE : RegExpTT.ESC_CHARACTER;
           }
-        case 65: break;
+        case 66: break;
         case 37: 
           { return RegExpTT.REDUNDANT_ESCAPE;
           }
-        case 66: break;
+        case 67: break;
         case 24: 
           { return RegExpTT.COMMA;
           }
-        case 67: break;
+        case 68: break;
         case 56: 
           { return RegExpTT.POS_LOOKBEHIND;
           }
-        case 68: break;
+        case 69: break;
         case 39: 
           { return RegExpTT.BAD_OCT_VALUE;
           }
-        case 69: break;
+        case 70: break;
         case 10: 
           { return commentMode ? com.intellij.psi.TokenType.WHITE_SPACE : RegExpTT.CTRL_CHARACTER;
           }
-        case 70: break;
+        case 71: break;
         case 30: 
           { yypopstate(); yypushstate(EMBRACED); return RegExpTT.LBRACE;
           }
-        case 71: break;
+        case 72: break;
         case 48: 
           { return StringEscapesTokenTypes.INVALID_UNICODE_ESCAPE_TOKEN;
           }
-        case 72: break;
+        case 73: break;
         case 57: 
           { return RegExpTT.NEG_LOOKBEHIND;
           }
-        case 73: break;
-        case 59: 
+        case 74: break;
+        case 60: 
           { return RegExpTT.UNICODE_CHAR;
           }
-        case 74: break;
+        case 75: break;
         case 55: 
           { if (xmlSchemaMode) { yypushback(1); return RegExpTT.CHAR_CLASS; } else return RegExpTT.CTRL;
           }
-        case 75: break;
+        case 76: break;
         case 35: 
           { yybegin(OPTIONS); return RegExpTT.SET_OPTIONS;
           }
-        case 76: break;
+        case 77: break;
         case 12: 
           { return RegExpTT.DOLLAR;
           }
-        case 77: break;
+        case 78: break;
         case 49: 
           { yypopstate(); return RegExpTT.QUOTE_END;
           }
-        case 78: break;
+        case 79: break;
         case 52: 
           { return RegExpTT.POS_LOOKAHEAD;
           }
-        case 79: break;
+        case 80: break;
         case 22: 
           { yypopstate(); return RegExpTT.RBRACE;
           }
-        case 80: break;
+        case 81: break;
         case 3: 
           { return RegExpTT.CHARACTER;
           }
-        case 81: break;
+        case 82: break;
         case 53: 
           { return RegExpTT.NEG_LOOKAHEAD;
           }
-        case 82: break;
+        case 83: break;
         case 41: 
           { return RegExpTT.ESC_CTRL_CHARACTER;
           }
-        case 83: break;
+        case 84: break;
         case 23: 
           { return RegExpTT.NAME;
           }
-        case 84: break;
+        case 85: break;
         case 50: 
           { return RegExpTT.ANDAND;
           }
-        case 85: break;
+        case 86: break;
         case 13: 
           { return RegExpTT.QUEST;
           }
-        case 86: break;
+        case 87: break;
         case 43: 
           { return RegExpTT.CHAR_CLASS;
           }
-        case 87: break;
+        case 88: break;
         case 17: 
           { return RegExpTT.MINUS;
           }
-        case 88: break;
+        case 89: break;
+        case 59: 
+          { return RegExpTT.COMMENT;
+          }
+        case 90: break;
         case 38: 
           { return yystate() != CLASS2 ? RegExpTT.BACKREF : RegExpTT.ESC_CHARACTER;
           }
-        case 89: break;
+        case 91: break;
         case 16: 
           { return RegExpTT.UNION;
           }
-        case 90: break;
+        case 92: break;
         case 44: 
           { if (xmlSchemaMode) return RegExpTT.CHAR_CLASS; else return StringEscapesTokenTypes.INVALID_CHARACTER_ESCAPE_TOKEN;
           }
-        case 91: break;
+        case 93: break;
         case 54: 
           { return RegExpTT.OCT_CHAR;
           }
-        case 92: break;
+        case 94: break;
         case 4: 
           { return RegExpTT.DOT;
           }
-        case 93: break;
+        case 95: break;
         case 32: 
           { yybegin(YYINITIAL); return RegExpTT.GROUP_END;
           }
-        case 94: break;
+        case 96: break;
         case 21: 
           { return RegExpTT.NUMBER;
           }
-        case 95: break;
+        case 97: break;
         case 45: 
           { yypushstate(PROP); return RegExpTT.PROPERTY;
           }
-        case 96: break;
+        case 98: break;
         case 19: 
           { return commentMode ? com.intellij.psi.TokenType.WHITE_SPACE : RegExpTT.CHARACTER;
           }
-        case 97: break;
+        case 99: break;
         case 33: 
           { handleOptions(); return RegExpTT.OPTIONS_OFF;
           }
-        case 98: break;
+        case 100: break;
         case 34: 
           { yybegin(YYINITIAL); return RegExpTT.COLON;
           }
-        case 99: break;
+        case 101: break;
         case 25: 
           { assert false : yytext();
           }
-        case 100: break;
+        case 102: break;
         case 27: 
           { yypopstate(); return RegExpTT.CLASS_END;
           }
-        case 101: break;
+        case 103: break;
         case 11: 
           { return RegExpTT.CARET;
           }
-        case 102: break;
+        case 104: break;
         case 1: 
           { handleOptions(); return RegExpTT.OPTIONS_ON;
           }
-        case 103: break;
+        case 105: break;
         case 29: 
           { yypopstate(); yypushback(1);
           }
-        case 104: break;
+        case 106: break;
         case 42: 
           { return yystate() != CLASS2 ? RegExpTT.BOUNDARY : RegExpTT.ESC_CHARACTER;
           }
-        case 105: break;
+        case 107: break;
         case 18: 
           { if (commentMode) { yypushstate(COMMENT); return RegExpTT.COMMENT; } else return RegExpTT.CHARACTER;
           }
-        case 106: break;
+        case 108: break;
         case 58: 
           { return RegExpTT.HEX_CHAR;
           }
-        case 107: break;
+        case 109: break;
         case 20: 
           { return RegExpTT.BAD_CHARACTER;
           }
-        case 108: break;
+        case 110: break;
         case 5: 
           { return RegExpTT.GROUP_BEGIN;
           }
-        case 109: break;
+        case 111: break;
         case 8: 
           { yypushstate(CLASS2); return RegExpTT.CLASS_BEGIN;
           }
-        case 110: break;
+        case 112: break;
         case 51: 
           { return RegExpTT.NON_CAPT_GROUP;
           }
-        case 111: break;
+        case 113: break;
         case 9: 
           { return StringEscapesTokenTypes.INVALID_CHARACTER_ESCAPE_TOKEN;
           }
-        case 112: break;
+        case 114: break;
         case 47: 
           { return RegExpTT.BAD_HEX_VALUE;
           }
-        case 113: break;
+        case 115: break;
         case 2: 
           { yypopstate(); return RegExpTT.COMMENT;
           }
-        case 114: break;
+        case 116: break;
         case 46: 
           { yypushstate(QUOTED); return RegExpTT.QUOTE_BEGIN;
           }
-        case 115: break;
+        case 117: break;
         case 26: 
           { yybegin(CLASS2); return RegExpTT.CHARACTER;
           }
-        case 116: break;
+        case 118: break;
         case 15: 
           { return RegExpTT.PLUS;
           }
-        case 117: break;
+        case 119: break;
         case 31: 
           { yybegin(YYINITIAL); return RegExpTT.BAD_CHARACTER;
           }
-        case 118: break;
+        case 120: break;
         default:
           if (zzInput == YYEOF && zzStartRead == zzCurrentPos) {
             zzAtEOF = true;
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/regexp-lexer.flex b/RegExpSupport/src/org/intellij/lang/regexp/regexp-lexer.flex
index c00164bcbf14..d2784722c228 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/regexp-lexer.flex
+++ b/RegExpSupport/src/org/intellij/lang/regexp/regexp-lexer.flex
@@ -195,6 +195,7 @@ HEX_CHAR=[0-9a-fA-F]
   "(?!"       { return RegExpTT.NEG_LOOKAHEAD;   }
   "(?<="      { return RegExpTT.POS_LOOKBEHIND;  }
   "(?<!"      { return RegExpTT.NEG_LOOKBEHIND;  }
+  "(?#" [^)]+ ")" { return RegExpTT.COMMENT;    }
 
   "(?"        { yybegin(OPTIONS); return RegExpTT.SET_OPTIONS; }
 }
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java b/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java
index 6f8c5f3e497c..e9d79c250f13 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java
@@ -22,6 +22,7 @@ import com.intellij.lang.annotation.Annotation;
 import com.intellij.lang.annotation.AnnotationHolder;
 import com.intellij.lang.annotation.Annotator;
 import com.intellij.lang.injection.InjectedLanguageManager;
+import com.intellij.psi.PsiComment;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiLanguageInjectionHost;
 import com.intellij.psi.util.PsiTreeUtil;
@@ -29,6 +30,7 @@ import org.intellij.lang.regexp.RegExpLanguageHost;
 import org.intellij.lang.regexp.RegExpTT;
 import org.intellij.lang.regexp.psi.*;
 import org.intellij.lang.regexp.psi.impl.RegExpPropertyImpl;
+import org.jetbrains.annotations.Nullable;
 
 public final class RegExpAnnotator extends RegExpElementVisitor implements Annotator {
     private AnnotationHolder myHolder;
@@ -100,10 +102,10 @@ public final class RegExpAnnotator extends RegExpElementVisitor implements Annot
 
     private static boolean isRedundantEscape(RegExpChar ch, String text) {
         if (text.length() <= 1) return false;
-        PsiLanguageInjectionHost host = InjectedLanguageManager.getInstance(ch.getProject()).getInjectionHost(ch);
-        if (host instanceof RegExpLanguageHost) {
+        RegExpLanguageHost host = findRegExpHost(ch);
+        if (host != null) {
           final char c = text.charAt(1);
-          final boolean needsEscaping = ((RegExpLanguageHost)host).characterNeedsEscaping(c);
+          final boolean needsEscaping = host.characterNeedsEscaping(c);
           return !needsEscaping;
         }
         else {
@@ -111,6 +113,15 @@ public final class RegExpAnnotator extends RegExpElementVisitor implements Annot
         }
     }
 
+    @Nullable
+    private static RegExpLanguageHost findRegExpHost(PsiElement element) {
+        PsiLanguageInjectionHost host = InjectedLanguageManager.getInstance(element.getProject()).getInjectionHost(element);
+        if (host instanceof RegExpLanguageHost) {
+            return (RegExpLanguageHost) host;
+        }
+        return null;
+    }
+
     public void visitRegExpProperty(RegExpProperty property) {
         final ASTNode category = property.getCategoryNode();
         if (category != null && !RegExpPropertyImpl.isValidCategory(category.getText())) {
@@ -151,6 +162,16 @@ public final class RegExpAnnotator extends RegExpElementVisitor implements Annot
         }
     }
 
+    @Override
+    public void visitComment(PsiComment comment) {
+        if (comment.getText().startsWith("(?#")) {
+            RegExpLanguageHost host = findRegExpHost(comment);
+            if (host == null || !host.supportsPerl5EmbeddedComments()) {
+                myHolder.createErrorAnnotation(comment, "Embedded comments are not supported");                
+            }
+        }
+    }
+
     private static boolean isEmpty(RegExpBranch[] branches) {
         for (RegExpBranch branch : branches) {
             if (branch.getAtoms().length > 0) {