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      1 /*
      2  * Copyright (C) 2008 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #ifndef AtomicStringHash_h
     30 #define AtomicStringHash_h
     31 
     32 #include <wtf/text/AtomicString.h>
     33 #include <wtf/HashTraits.h>
     34 
     35 namespace WTF {
     36 
     37     struct AtomicStringHash {
     38         static unsigned hash(const AtomicString& key)
     39         {
     40             return key.impl()->existingHash();
     41         }
     42 
     43         static bool equal(const AtomicString& a, const AtomicString& b)
     44         {
     45             return a == b;
     46         }
     47 
     48         static const bool safeToCompareToEmptyOrDeleted = false;
     49     };
     50 
     51     // AtomicStringHash is the default hash for AtomicString
     52     template<> struct HashTraits<WTF::AtomicString> : GenericHashTraits<WTF::AtomicString> {
     53         static const bool emptyValueIsZero = true;
     54         static void constructDeletedValue(WTF::AtomicString& slot) { new (&slot) WTF::AtomicString(HashTableDeletedValue); }
     55         static bool isDeletedValue(const WTF::AtomicString& slot) { return slot.isHashTableDeletedValue(); }
     56     };
     57 
     58 }
     59 
     60 using WTF::AtomicStringHash;
     61 
     62 #endif
     63