diff --git a/JavaScriptCore/runtime/RegExpKey.h b/JavaScriptCore/runtime/RegExpKey.h
new file mode 100644
index 0000000..e5ab438
--- /dev/null
+++ b/JavaScriptCore/runtime/RegExpKey.h
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2010 University of Szeged
+ * Copyright (C) 2010 Renata Hodovan (hodovan@inf.u-szeged.hu)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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 with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL UNIVERSITY OF SZEGED OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "UString.h"
+
+#ifndef RegExpKey_h
+#define RegExpKey_h
+
+namespace JSC {
+
+struct RegExpKey {
+    int flagsValue;
+    RefPtr<UString::Rep> pattern;
+
+    RegExpKey()
+        : flagsValue(0)
+    {
+    }
+
+    RegExpKey(int flags)
+        : flagsValue(flags)
+    {
+    }
+
+    RegExpKey(int flags, const UString& pattern)
+        : flagsValue(flags)
+        , pattern(pattern.rep())
+    {
+    }
+
+    RegExpKey(int flags, const PassRefPtr<UString::Rep> pattern)
+        : flagsValue(flags)
+        , pattern(pattern)
+    {
+    }
+
+    RegExpKey(const UString& flags, const UString& pattern)
+        : pattern(pattern.rep())
+    {
+        flagsValue = getFlagsValue(flags);
+    }
+
+    int getFlagsValue(const UString flags) 
+    {
+        flagsValue = 0;
+        if (flags.find('g') != UString::NotFound)
+            flagsValue += 4;
+        if (flags.find('i') != UString::NotFound)
+            flagsValue += 2;
+        if (flags.find('m') != UString::NotFound)
+            flagsValue += 1;
+        return flagsValue;
+    }
+};
+} // namespace JSC
+
+namespace WTF {
+template<typename T> struct DefaultHash;
+template<typename T> struct RegExpHash;
+
+inline bool operator==(const JSC::RegExpKey& a, const JSC::RegExpKey& b) 
+{
+    if (a.flagsValue != b.flagsValue)
+        return false;
+    if (!a.pattern)
+        return !b.pattern;
+    if (!b.pattern)
+        return false;
+    return equal(a.pattern.get(), b.pattern.get());
+}
+
+template<> struct RegExpHash<JSC::RegExpKey> {
+    static unsigned hash(const JSC::RegExpKey& key) { return key.pattern->hash(); }
+    static bool equal(const JSC::RegExpKey& a, const JSC::RegExpKey& b) { return a == b; }
+    static const bool safeToCompareToEmptyOrDeleted = false;
+};
+
+template<> struct DefaultHash<JSC::RegExpKey> {
+    typedef RegExpHash<JSC::RegExpKey> Hash;
+};
+
+template<> struct HashTraits<JSC::RegExpKey> : GenericHashTraits<JSC::RegExpKey> {
+    static void constructDeletedValue(JSC::RegExpKey& slot) { slot.flagsValue = -1; }
+    static bool isDeletedValue(const JSC::RegExpKey& value) { return value.flagsValue == -1; }
+};
+} // namespace WTF
+
+#endif // RegExpKey_h