Fix issue 246.

src/parser.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3588 matching lines @@
 
 RegExpParser::RegExpParser(FlatStringReader* in,
                            Handle<String>* error,
                            bool multiline)
   : current_(kEndMarker),
     has_more_(true),
     multiline_(multiline),
     next_pos_(0),
     in_(in),
     error_(error),
-    simple_(true),
+    simple_(false),
     contains_anchor_(false),
     captures_(NULL),
     is_scanned_for_captures_(false),
     capture_count_(0),
     failed_(false) {
   Advance(1);
 }
 
 
 uc32 RegExpParser::Next() {
@@ skipping 49 matching lines @@
 }
 
 
 // Pattern ::
 //   Disjunction
 RegExpTree* RegExpParser::ParsePattern() {
   RegExpTree* result = ParseDisjunction(CHECK_FAILED);
   if (has_more()) {
     ReportError(CStrVector("Unmatched ')'") CHECK_FAILED);
   }
+  // If the result of parsing is a literal string atom, and it has the
+  // same length as the input, then the atom is identical to the input.
+  if (result->IsAtom() && result->AsAtom()->length() == in()->length()) {
+    simple_ = true;
+  }
   return result;
 }
 
 
 bool RegExpParser::CaptureAvailable(int index) {
   if (captures_ == NULL) return false;
   if (index >= captures_->length()) return false;
   RegExpCapture* capture = captures_->at(index);
   return capture != NULL && capture->available() == CAPTURE_AVAILABLE;
 }
@@ skipping 179 matching lines @@
           builder.AddCharacter('u');
         }
         break;
       }
       default:
         // Identity escape.
         builder.AddCharacter(Next());
         Advance(2);
         break;
       }
-      simple_ = false;
       break;
     case '{': {
       int dummy;
       if (ParseIntervalQuantifier(&dummy, &dummy)) {
         ReportError(CStrVector("Nothing to repeat") CHECK_FAILED);
       }
       // fallthrough
     }
     default:
       builder.AddCharacter(current());
@@ skipping 36 matching lines @@
         continue;
       }
     default:
       continue;
     }
     bool is_greedy = true;
     if (current() == '?') {
       is_greedy = false;
       Advance();
     }
-    simple_ = false;  // Adding quantifier might *remove* look-ahead.
     builder.AddQuantifierToAtom(min, max, is_greedy);
   }
 }
 
 class SourceCharacter {
  public:
   static bool Is(uc32 c) {
     switch (c) {
       // case ']': case '}':
       // In spidermonkey and jsc these are treated as source characters
@@ skipping 564 matching lines @@
                        start_position,
                        is_expression);
   return result;
 }
 
 
 #undef NEW
 
 
 } }  // namespace v8::internal